Original quantitative research – Using health service data to understand unregulated toxic drug deaths in Alberta (2018–2023): an ecological study

Abstract

Introduction: Ten years into the most acute phase of the toxic drug crisis in Canada, trends in drug-related deaths remain poorly understood. This is hindered by delayed reporting of drug deaths in some provinces, including Alberta. We used publicly available emergency medical services (EMS) and supervised consumption site (SCS) utilization data to examine their associations with drug poisoning deaths to assess if these measures could serve as reliable proxies for fatalities to support evidence-based public health responses.

Methods: Data on Alberta-wide EMS dispatches for opioid poisoning, Alberta-wide drug deaths, and SCS drug poisoning events at the SCS in Calgary from January 2018 to March 2023 were analyzed. We used linear regression modelling to investigate the association between EMS dispatches and drug deaths (by month) and between SCS drug poisoning events and drug deaths (by month).

Results: Significant associations were found between drug-related deaths in Alberta and both the number of EMS dispatches (β = .06, 95% CI: 0.05–0.06) and SCS drug poisoning events (β = .73, 95% CI: 0.57–0.88), suggesting these measures mirror drug-related deaths in the province. Inverse associations were also found between drug-related deaths and SCS visits as well as visits in which drugs were consumed.

Conclusion: Drug poisoning events recorded in EMS or SCS data may serve as a proxy for understanding trends in drug deaths. These alternative data are often publicly available and may help inform public health response to periods of increased death risk when official death data are delayed or unavailable.

Keywords: drug overdoses, emergency medical services, harm reduction, substance-related harms, opioids

Introduction

The toxic drug crisis is an urgent Canadian public health issue, with increasing mortality and morbidity associated with the use of an unregulated drug supply contaminated with clandestinely produced fentanyl and other substances.^{Footnote 1Footnote 2} Since January 2016, more than 53 000 Canadians have died from drug poisoning, including more than 10 500 Albertans.^{Footnote 2} Alberta, British Columbia and Ontario account for 87% of all drug-related deaths in Canada.^{Footnote 2} Notably, due to colonial violence, discrimination and racism, First Nations people disproportionately account for drug-related deaths in Alberta, prompting multiple state-of-emergency declarations in some communities.^{Footnote 3Footnote 4Footnote 5Footnote 6}

The Government of Alberta publicly shares drug death data. Preliminary fatality counts typically lag by three to four months, while EMS dispatches are usually released with less than a month’s lag. However, public EMS opioid-related dispatch reports are often incomplete as they lack non-opioid drug poisoning events and other emergency service dispatches (e.g. fire and police departments). They also include all dispatches to an opioid-related event which may or may not result in transport to hospital.^{Footnote 7} Meanwhile, questions have been raised about the accuracy of fatality numbers.^{Footnote 3Footnote 8Footnote 9Footnote 10Footnote 11} The Public Health Agency of Canada reports an average delay of six months between the occurrence of a death and its inclusion in national death data.^{Footnote 12} In Alberta, this delay can reach nine months, and since 2021, Alberta has been the only province or territory not reporting stimulant deaths to the federal government.^{Footnote 2Footnote 13}

Without timely, accessible and high-resolution data, it is difficult to implement interventions that effectively respond to this public health emergency. Although there was a year-over-year decrease in total drug-related deaths from 2024 to 2025, this decrease has not been experienced uniformly.^{Footnote 2} Since 2025, there has been a sharp increase in carfentanil-related deaths, and some cities, such as Edmonton, continue to experience record drug-related deaths.^{Footnote 14} Given this ongoing public health crisis and the lack of available and transparent data, this study aimed to determine whether additional health service data (i.e. EMS dispatches for drug poisonings and drug poisonings that occur during SCS utilization) can be used to understand trends in drug deaths in Alberta, by serving as a proxy for unregulated drug supply toxicity. Supplementing fatality trends with data from these health services could help guide targeted responses that prevent further deaths.

While EMS data are collected and reported publicly with less lag time, public transparency on SCS data has been significantly curtailed since 2024.^{Footnote 15} Both services engage a large number of people who use drugs daily.^{Footnote 16} EMS are dispatched to hundreds of drug poisoning events weekly in Alberta.^{Footnote 3Footnote 17} SCSs are evidence-based harm reduction interventions that provide a hygienic place to consume pre-obtained drugs, and access to wraparound health and social services, such as primary care and housing supports.^{Footnote 18} As of February 2026, there are 32 SCSs in Canada, supported by global evidence on their effectiveness of preventing drug poisoning deaths and supporting public safety.^{Footnote 19Footnote 20} However, no research has considered the utility of SCS and EMS data as proxies for drug death trends. A proof-of-concept study used Ottawa Paramedic Service data to provide epidemiologic data on municipal opioid overdoses and demonstrated that EMS data were beneficial for assessing trends in the unregulated drug supply but called for further validation.^{Footnote 21} An ecological study and spatial analysis using data from Toronto, Ontario neighbourhoods demonstrated the association between municipal SCS implementation and reduced deaths.^{Footnote 22} This study provides further validation using health services data (from EMS and SCS) to understand current drug deaths trends. Specifically, we aim to understand:

1. what are the statistical correlations between adverse events and utilization at SCSs in Alberta and Calgary, and the respective rates of drug poisoning deaths in the province and city?
2. is there a statistically significant correlation between the number of EMS dispatches for suspected drug poisonings in Alberta and the overall number of drug poisoning deaths in the province?

Methods

Study design and time period

This secondary data analysis investigates drug deaths in Alberta from 1 January 2018 to 31 December 2023 and the link to SCS utilization, SCS drug poisoning events, and opioid-related EMS dispatches.

Study setting

Alberta is a province in Western Canada (population: 5 million) that has experienced some of the highest annual drug poisoning deaths in Canada (2140 deaths in 2023).^{Footnote 2Footnote 23} Despite this, Alberta is shifting away from a multipronged drug poisoning prevention strategy that includes evidence-based harm reduction interventions such as SCSs. The new approach, termed the “Alberta Recovery Model,” prioritizes abstinence-based and recovery-oriented approaches to care, including a highly criticized plan to enact compulsory bed-based treatment and forced abstinence through the Compassionate Intervention Act. As a result of these changes in political ideology, harm-reduction tactics have been de-emphasized and several SCSs have been closed in tandem.^{Footnote 24Footnote 25Footnote 26Footnote 27} The high rates of drug poisoning have also created considerable pressure on the strained EMS system.^{Footnote 28} In 2024, overtime among Albertan paramedics increased 81% compared to 2021, and there was an average of 40 unfilled shifts per day in Edmonton.^{Footnote 29Footnote 30}

Ethics approval was provided by University of Alberta Health Research Ethics Board – Health Panel (Pro00133344).

Data sources

Secondary data were collected in aggregate from the Government of Alberta Provincial Substance Use Surveillance Dashboard, the Alberta Health Services SCS Monthly Reports for Calgary SCS, and Alberta Health Services – EMS Research and Science (see Table 1 for data sources and variables).

Table 1. Additional information on data sources

Data source and period	Variable of interest	Variable notes
Government of Alberta Provincial Substance Use Surveillance Dashboard (PSUSD); January 2018–December 2023	Drug poisoning deaths in Alberta	“Any substance”, Alberta-wide monthly counts
	EMS responses to opioid-related events	Monthly counts, Alberta-wide
	Rate of opioid responses to total EMS responses (%)	Calculated from EMS responses to opioid-related events (PSUSD) and total emergency events (PSUSD)
	Drug poisoning rate	“Any substance”, Alberta-wide monthly rates per 100 000 population
	Drug poisoning deaths_Calgary	Monthly counts, Calgary only
	Drug poisoning rate_Calgary	“Any substance”, monthly rates per 100 000 population for Calgary municipality
	Drug poisoning deaths Alberta not Calgary	Calculated from Alberta and Calgary monthly counts (subtracted Calgary counts from Alberta counts)
Alberta Health Services monthly reports for Calgary SCS; January 2018–December 2023	Client_visits	The number of clients who visit per month, as recorded and reported by Calgary SCS staff
	Drug_consumption_events	Monthly drug consumption events, Calgary SCS
	Overdoses	Monthly overdoses, Calgary SCS
	Poisoning_rate_%	Drug poisoning rate (overdoses per number of times drugs consumed), Calgary SCS
Alberta Health Services – EMS Research and Science; January 2018–March 2023	Total EMS emergency events	Monthly counts; Alberta-wide
	Overdose/Poisoning emergency events	For total emergency events, Overdose/Poisoning events were identified by Card Type 23; Alberta-wide
	Overdose as a proportion of all events	Monthly counts, Overdose/Poisoning as a proportion of total EMS events; Alberta-wide

Under federal law, SCSs are distinguished from overdose prevention sites (OPSs) by authorization pathway and typically are more permanent and offer a larger number of ancillary services compared to OPSs. In this study, SCS utilization refers to the number of drug consumption events within the site. SCS drug poisoning events refer to drug consumption events that necessitate a medical response, including naloxone or oxygen administration. It should be noted that none of these events in Alberta have been fatal. EMS dispatches refer to events where EMS are dispatched to respond to a potential opioid-related event.

Drug poisoning events reported at SCSs are expected to function as a proxy for the toxicity of the unregulated (illegal) drug supply, given that SCS clients bring unregulated drugs into SCSs for consumption. Quarterly data on drug poisoning events and rate of drug poisoning were only available for the full study period (2018–2023) for Calgary and Edmonton. Given that the Calgary SCS comprises the highest proportion of province-wide SCS visits and most complete data available during the study period, the publicly available Calgary SCS data were used to investigate associations between drug poisonings in SCSs and drug death rates in the municipality of Calgary. Data were limited to shorter time frames for other sites including Grand Prairie (2019 Q1–2023 Q4), Lethbridge AHS OPS (2020 Q3–2023 Q4), Lethbridge ARCHES (2018 Q1–2020 Q3) and Red Deer (2018 Q4–2023 Q4). SCS utilization across Alberta was calculated by summing quarterly counts from all sites for each variable (see Table 2). From the site’s opening in 2017, Calgary SCS was the only site publicly posting monthly reports that included the number of consumption events and drug poisonings during consumption, but these were removed from public access in October 2024 and further reporting was halted.^{Footnote 15} However, visits to the Calgary SCS represented greater than one-fifth of total provincial SCS visits for the full study period, and drug deaths in Calgary made up 23% to 43% of the provincial total. Focussing on the detailed Calgary data provides a wide-angle view of the provincial crisis from the province’s largest city.

Table 2. Comparison of drug deaths and related events in Calgary and Alberta

Monthly drug deaths^{Footnote a} (section 1 of 3)

Year	Calgary		Alberta
	Deaths (SD)	Deaths per 100 000 (SD)	Deaths (SD)	Deaths per 100 000 (SD)
2018–2023	41.5 (14.7)	34.4 (10.9)	123.4 (44.5)	33.0 (11.3)
2018	27.8 (6.6)	28.4 (4)	79.7 (9.1)	22.3 (2.6)
2019	30.2 (12.8)	21.4 (6.2)	66.7 (13.1)	18.4 (3.6)
2020	43.5 (4.8)	32.9 (9.5)	117.3 (33.4)	31.9 (9.1)
2021	49.5 (11.2)	41.4 (7.3)	157.2 (22.1)	42.6 (6)
2022	56.6 (12.1)	38.2 (8.7)	146.9 (20.9)	39.1 (5.6)
2023	41.3 (14.5)	44.3 (9.8)	172.4 (18.7)	44.1 (4.8)

Quarterly supervised consumption sites usage^{Footnote b} (section 2 of 3)

Year	Calgary		Alberta
	Drug poisoning events	Drug poisoning rateFootnote c	Drug poisoning events	Drug poisoning rateFootnote c
2018–2023	340 (164.6)	3.2 (2.2)	1052.3 (371.3)	2.2 (1.1)
2018	179 (35.6)	1.5 (0.3)	619 (396.9)	1.2 (0.2)
2019	181.8 (16.5)	1.1 (0.1)	1034.3 (36.7)	1 (0.1)
2020	227.5 (81.9)	1.8 (0.9)	806 (298.1)	1.6 (0.7)
2021	518.5 (97.9)	5.0 (1.5)	1423.8 (194.4)	3.2 (0.4)
2022	404.3 (93)	4.1 (1.1)	1174.3 (371.5)	2.6 (0.8)
2023	529 (25.9)	5.9 (0.4)	1256.8 (205.6)	3.4 (0.4)

Monthly emergency medical services (EMS) usage^{Footnote aFootnote d} (section 3 of 3)

Year	Calgary		Alberta
	Dispatches for opioid poisoning	% of EMS dispatches for opioid poisoning	Dispatches for opioid poisoning	% of EMS dispatches for opioid poisoningFootnote e
2018–2023Footnote f	N/A	N/A	1854.5 (668.5)	5.4% (1.5)
2018	N/A	N/A	1303.1 (123.1)	4.4% (0.4)
2019	N/A	N/A	1190.4 (130.5)	3.9% (0.4)
2020	N/A	N/A	1601.3 (326.1)	5.0% (0.9)
2021	N/A	N/A	2403.5 (540.4)	6.6% (1.0)
2022	N/A	N/A	2492.8 (229.3)	6.7% (0.7)
2023	N/A	N/A	N/A	N/A

Measures

Primary outcome

The primary outcome is provincial drug poisoning by any substance per month.

Exposures

Exposure variables are the Alberta-wide monthly counts of total EMS emergency events, poisoning emergency events, and poisoning emergency events as a proportion of all EMS events. Additionally, Calgary SCS data on monthly client visits, drug consumption events, poisonings, and drug poisoning rates (poisonings per number of times drugs consumed) were analyzed.

Covariate

We controlled for seasonality in months based on literature that highlights seasonality in drug deaths.^{Footnote 31}

Data analysis

Drug poisoning rates at the Calgary SCS were calculated by normalizing drug poisoning events to total drug consumption events for the same time frame. Associations between variables were assessed with a generalized linear regression model and Spearman’s correlation. We used multiple linear regression modelling to examine the association between Calgary SCS utilization (site visits, drug consumption events, poisoning events, poisoning rate) and drug poisoning deaths in Alberta and the association between drug EMS dispatches (total, opioid-related, and non-opioid-related) and poisoning deaths in Alberta. All regression models were adjusted for seasonality. Statistics were performed in GraphPad Prism (GraphPad, San Diego, CA) and Stata18 (StataCorp, College Station, TX). Graphs were prepared in GraphPad Prism v10.

Results

From 1 January 2018 to 31 December 2023, a monthly average of 123.4 drug deaths (33.0 deaths per 100 000 people) was observed in Alberta, while a monthly average of 41.5 drug deaths (34.4 deaths per 100 000 people) was observed in Calgary (Table 2). Provincially, drug deaths peaked in 2023 with a monthly average of 172.4 deaths (44.1 deaths per 100 000 people). In Calgary, the monthly average for drug deaths was 41.3, at a rate of 44.3 deaths per 100 000 people. Drug deaths in Calgary represented 23% to 43% of the total in Alberta throughout the study period.

Association between drug poisoning deaths and supervised consumption site events in Alberta

Publicly available data from each SCS in Alberta revealed a quarterly provincial average of 1052 drug poisoning events (2.2 drug poisoning events per consumption event) from 2018 to 2023 (Table 1, Figure 1). The association between quarterly provincial drug poisonings during supervised consumption and drug poisoning deaths (per 100 000) showed close alignment (Figure 1C) and strong positive correlation from 2018 to 2023 (ρ = 0.94, p < 0.0001; Figure 1D). Quarterly drug poisoning events reported across all Alberta SCS/OPS exhibited a moderate positive correlation with quarterly provincial drug deaths (ρ = 0.59, p = 0.0024; Figure 1E). Notably, total site visits to Alberta SCS were negatively correlated with provincial drug deaths (ρ = −0.59, p = 0.0024; Figure 1F).

Figure 1: Descriptive text

A. Quarterly number of visits (bars) per supervised consumption site across Alberta from January 2018 to December 2023

Year	Quarter	Calgary SCS Visits	Edmonton SCS Visits	Edmonton OPS Visits	Grand Prairie SCS Visits	Lethbridge OPS Visits	Lethbridge SCS	Red Deer OPS Visits	Total Visits	Alberta total drug poisoning events per client visits (%)
2018	Q1	7469	390	N/A	N/A	N/A	2375		10234	1.5
	Q2	12854	8974	N/A	N/A	N/A	26464		48292	1.07
	Q3	13548	7975	N/A	N/A	N/A	42450		63973	1.09
	Q4	18051	11961	N/A	N/A	N/A	56562	4639	91213	1.21
2019	Q1	16623	17489	N/A	298	N/A	60260	9504	104174	1.01
	Q2	16694	15641	N/A	2028	N/A	59901	10537	104801	0.99
	Q3	16880	13475	N/A	2646	N/A	59781	12295	105077	1.01
	Q4	18831	16899	N/A	3668	N/A	66168	13448	119014	0.82
2020	Q1	19071	18018	N/A	3172	N/A	58719	15432	114412	0.97
	Q2	12535	6657	N/A	1221	N/A	12101	8241	40755	1.44
	Q3	10639	7115	N/A	1441	1309	5640	8705	34849	1.48
	Q4	11480	6117	1628	1746	10061	N/A	8220	39252	2.59
2021	Q1	11288	6966	5868	1987	10327	N/A	7697	44133	2.81
	Q2	11624	8841	1345	2138	13020	N/A	7253	44221	2.89
	Q3	9781	9513	N/A	1962	14632	N/A	10397	46285	3.35
	Q4	9389	10500	N/A	2124	14122	N/A	9747	45882	3.55
2022	Q1	9406	9807	1346	2063	12157	N/A	10748	45527	3.55
	Q2	9598	9802	N/A	1858	14229	N/A	9252	44739	2.45
	Q3	10402	9626	N/A	1444	12935	N/A	9391	43798	1.65
	Q4	10152	11498	N/A	1764	11594	N/A	9897	44905	2.82
2023	Q1	9395	11794	N/A	2104	9227	N/A	9962	42482	3.55
	Q2	8554	7517	N/A	1685	8326	N/A	7244	33326	3.9
	Q3	8588	8450	N/A	1200	10620	N/A	5887	34745	2.91
	Q4	9326	10295	N/A	1406	9961	N/A	6346	37334	3.24

B. Quarterly drug poisoning events (%) at supervised consumption sites across Alberta from 2018 to December 2023

Year	Quarter	Drug poisoning events per client visit in Alberta, all sites (%)	Drug poisoning events per client visit, Edmonton SCS (%)	Drug poisoning events per client visit, Calgary SCS (%)	Drug poisoning events per client visit, Grand Prairie SCS (%)	Drug poisoning events per client visit, Lethbridge OPS (%)	Drug poisoning events per client visit, Lethbridge SCS (%)	Drug poisoning events per client visit, Red Deer OPS (%)	Drug poisoning events per client visit, Edmonton OPS (%)
2018	Q1	1.5	0.77	1.75	N/A	N/A	0.8	N/A	N/A
	Q2	1.07	1.06	1.5	N/A	N/A	0.86	N/A	N/A
	Q3	1.09	1.37	1.59	N/A	N/A	0.89	N/A	N/A
	Q4	1.21	1.11	0.98	N/A	N/A	1.2	2.52	N/A
2019	Q1	1.01	0.86	1.1	5.37	N/A	0.79	2.39	N/A
	Q2	0.99	1.16	0.95	2.07	N/A	0.69	2.33	N/A
	Q3	1.01	0.65	1.14	1.4	N/A	0.64	2.94	N/A
	Q4	0.82	0.76	1.02	1.31	N/A	0.49	2.13	N/A
2020	Q1	0.97	0.83	0.96	0.95	N/A	0.54	2.73	N/A
	Q2	1.44	0.99	1.44	0.41	N/A	0.97	2.65	N/A
	Q3	1.48	1.12	1.83	0.42	1.45	0.41	2.21	N/A
	Q4	2.59	1.75	3.05	0.97	1.52	N/A	4.37	1.9
2021	Q1	2.81	2.64	3.8	0.7	1.47	N/A	4.77	1.58
	Q2	2.89	4.31	3.88	1.31	0.96	N/A	3.83	1.04
	Q3	3.35	3.91	5.65	1.73	1.18	N/A	4.04	N/A
	Q4	3.55	3.07	6.83	1.79	1.5	N/A	4.25	N/A
2022	Q1	3.55	3.92	5.34	2.71	1.65	N/A	3.79	4.9
	Q2	2.45	2.18	3.59	2.48	0.7	N/A	4.23	N/A
	Q3	1.65	1.43	2.95	1.45	0.25	N/A	2.37	N/A
	Q4	2.82	2.14	4.56	1.7	0.9	N/A	4.26	N/A
2023	Q1	3.55	3.17	5.86	3.47	2.25	N/A	3.01	N/A
	Q2	3.9	3.62	6.44	6.23	1.14	N/A	3.84	N/A
	Q3	2.91	2.41	5.97	12.17	0.58	N/A	1.46	N/A
	Q4	3.24	2.38	5.37	2.35	0.77	N/A	5.56	N/A

C. Quarterly number of drug poisoning events recorded at all supervised consumption sites across Alberta (bars), overlaid with the drug poisoning deaths (%) across Alberta per 100 000 people from 2018 to December 2023

Year	Quarter	Alberta total SCS drug poisoning events	Drug poisoning deaths per 100 000
2018	Q1	153	21.13
	Q2	516	23.37
	Q3	700	22.47
	Q4	1107	22.10
2019	Q1	1051	18.73
	Q2	1041	21.13
	Q3	1064	18.27
	Q4	981	15.33
2020	Q1	1105	18.87
	Q2	587	35.33
	Q3	515	37.73
	Q4	1017	35.83
2021	Q1	1239	37.30
	Q2	1277	39.63
	Q3	1552	42.70
	Q4	1627	50.67
2022	Q1	1615	45.13
	Q2	1096	35.90
	Q3	721	34.67
	Q4	1265	40.60
2023	Q1	1506	42.60
	Q2	1301	47.97
	Q3	1011	45.33
	Q4	1209	40.37

D. Scatterplots of drug deaths in Alberta as a function of the following variables at supervised consumption services: drug poisoning events per client visit (%)

Year	Quarter	Drug poisoning events per client visit (%)	Drug Poisoning Deaths in Alberta
2018	Q1	1.5	75.67
	Q2	1.07	83.67
	Q3	1.09	80.33
	Q4	1.21	79.00
2019	Q1	1.01	68.00
	Q2	0.99	76.67
	Q3	1.01	66.33
	Q4	0.82	55.67
2020	Q1	0.97	69.33
	Q2	1.44	129.67
	Q3	1.48	138.67
	Q4	2.59	131.67
2021	Q1	2.81	137.67
	Q2	2.89	146.33
	Q3	3.35	157.67
	Q4	3.55	187.00
2022	Q1	3.55	169.67
	Q2	2.45	135.00
	Q3	1.65	130.33
	Q4	2.82	152.67
2023	Q1	3.55	166.67
	Q2	3.9	187.67
	Q3	2.91	177.33
	Q4	3.24	158.00

E. Scatterplots of drug deaths in Alberta as a function of the following variables at supervised consumption services: total client visits

Year	Quarter	Total Visits	Drug Poisoning Deaths in Alberta
2018	Q1	10234	75.67
	Q2	48292	83.67
	Q3	63973	80.33
	Q4	91213	79.00
2019	Q1	104174	68.00
	Q2	104801	76.67
	Q3	105077	66.33
	Q4	119014	55.67
2020	Q1	114412	69.33
	Q2	40755	129.67
	Q3	34849	138.67
	Q4	39252	131.67
2021	Q1	44133	137.67
	Q2	44221	146.33
	Q3	46285	157.67
	Q4	45882	187.00
2022	Q1	45527	169.67
	Q2	44739	135.00
	Q3	43798	130.33
	Q4	44905	152.67
2023	Q1	42482	166.67
	Q2	33326	187.67
	Q3	34745	177.33
	Q4	37334	158.00

F. Scatterplots of drug deaths in Alberta as a function of the following variables at supervised consumption services: total drug poisoning events

Year	Quarter	Total Adverse Events	Drug Poisoning Deaths in Alberta
2018	Q1	153	75.67
	Q2	516	83.67
	Q3	700	80.33
	Q4	1107	79.00
2019	Q1	1051	68.00
	Q2	1041	76.67
	Q3	1064	66.33
	Q4	981	55.67
2020	Q1	1105	69.33
	Q2	587	129.67
	Q3	515	138.67
	Q4	1017	131.67
2021	Q1	1239	137.67
	Q2	1277	146.33
	Q3	1552	157.67
	Q4	1627	187.00
2022	Q1	1615	169.67
	Q2	1096	135.00
	Q3	721	130.33
	Q4	1265	152.67
2023	Q1	1506	166.67
	Q2	1301	187.67
	Q3	1011	177.33
	Q4	1209	158.00

Abbreviations: AHS, Alberta Health Services; OPS, overdose prevention site; SCS, supervised consumption site.
Notes: (A) Quarterly number of visits (bars) per supervised consumption site across Alberta from January 2018 to December 2023, colour coded by site, overlaid with the total province-wide drug poisoning events (%) (circles; right y-axis) expressed as drug poisonings recorded as a percentage of total client visits at supervised consumption sites across Alberta. (B) Quarterly drug poisoning events (%) at supervised consumption sites across Alberta from 2018 to December 2023, colour coded by site, overlaid with the Alberta drug poisoning events (%) (X). (C) Quarterly number of drug poisoning events recorded at all supervised consumption sites across Alberta (bars), overlaid with the drug poisoning deaths (%) across Alberta per 100 000 people from 2018 to December 2023 (red squares; right y-axis). (D–F) Scatterplots of drug deaths in Alberta as a function of the following variables at supervised consumption services: (D) drug poisoning events per client visit (%), and (E) total client visits, and (F) total drug poisoning events. Individual data points correspond to quarterly data collected across all provincial SCSs from January 2018 to December 2023, with symbols denoting the year. Regression lines were fitted using a generalized linear model and error bars indicate 95% confidence intervals. Associations were assessed by Spearman’s correlation, with the rho (ρ) value and p value shown above each scatterplot.
(D) Spearman rho = 0.9441; **** p < 0.0001; (E) Spearman rho = −0.5904; ** p = 0.0024; (F) Spearman rho = 0.5904; ** p = 0.0024

Association between drug poisoning deaths and supervised consumption site utilization in Calgary, Alberta

At the onset of the COVID-19 pandemic, the proportion of drug consumption events at Calgary SCS that resulted in a drug poisoning event increased (Figure 2A). Although visits to Calgary SCS started to decline in the first months of the pandemic through 2023, there was an increase in SCS drug poisoning events from April to December 2021. Drug poisoning at Calgary SCS moved in tandem with death patterns in Calgary. There was a negative correlation between monthly municipal drug deaths and both site visits (ρ = −0.67, p < 0.0001; Figure 2B) and drug consumption events (ρ = −0.66, p < 0.0001; Figure 2C) at Calgary SCS. Monthly drug poisoning deaths in Calgary also correlated with the number of drug poisoning events reported at Calgary SCS (ρ = 0.70, p < 0.0001; Figure 2D) and the proportion of drug consumption events with a drug poisoning at Calgary SCS (ρ = 0.78, p < 0.0001; Figure 2E).

Figure 2: Descriptive text

A. Monthly number of drug consumption events (grey) and drug poisoning events (red) recorded at Calgary SCS from January 2018 to December 2023

Month and year	Calgary SCS drug consumption events	Overdoses at Calgary SCS	Calgary SCS drug poisoning rate (%)
Jan-18	1687	35	2.07
Feb-18	2003	29	1.45
Mar-18	2683	67	2.5
Apr-18	2867	44	1.53
May-18	4131	71	1.72
Jun-18	3545	78	2.2
Jul-18	3295	67	2.03
Aug-18	3571	59	1.65
Sep-18	4162	89	2.14
Oct-18	4664	63	1.35
Nov-18	4745	62	1.31
Dec-18	5033	52	1.03
Jan-19	4936	60	1.22
Feb-19	3877	70	1.81
Mar-19	4409	53	1.2
Apr-19	5309	38	0.72
May-19	4942	63	1.27
Jun-19	4532	57	1.26
Jul-19	4804	90	1.87
Aug-19	4928	64	1.3
Sep-19	4361	39	0.89
Oct-19	5311	49	0.92
Nov-19	5420	73	1.35
Dec-19	5800	71	1.22
Jan-20	5994	47	0.78
Feb-20	6069	54	0.89
Mar-20	5538	83	1.5
Apr-20	3988	87	2.18
May-20	3537	52	1.47
Jun-20	3382	42	1.24
Jul-20	2965	63	2.12
Aug-20	3003	50	1.67
Sep-20	3210	82	2.55
Oct-20	3427	81	2.36
Nov-20	3555	78	2.19
Dec-20	3467	69	1.99
Jan-21	3580	104	2.91
Feb-21	3052	89	2.92
Mar-21	3616	104	2.88
Apr-21	3594	85	2.37
May-21	3540	138	3.9
Jun-21	2862	136	4.75
Jul-21	2611	146	5.59
Aug-21	2875	131	4.56
Sep-21	2518	189	7.51
Oct-21	2891	176	6.09
Nov-21	2636	164	6.22
Dec-21	2692	214	7.95
Jan-22	2518	172	6.83
Feb-22	2669	148	5.55
Mar-22	3115	120	3.85
Apr-22	2853	101	3.54
May-22	2717	90	3.31
Jun-22	2751	103	3.74
Jul-22	3162	87	2.75
Aug-22	2758	68	2.47
Sep-22	2615	67	2.56
Oct-22	3019	119	3.94
Nov-22	3014	130	4.31
Dec-22	2806	165	5.88
Jan-23	2624	137	5.22
Feb-23	2548	126	4.95
Mar-23	2684	226	8.42
Apr-23	2539	210	8.27
May-23	2139	143	6.68
Jun-23	2031	140	6.89
Jul-23	2431	139	5.71
Aug-23	2185	174	7.96
Sep-23	2192	158	7.21
Oct-23	2609	182	6.98
Nov-23	2606	211	8.09
Dec-23	2759	218	7.9

B. Scatterplots of drug poisoning deaths in Calgary as a function of Calgary SCS: client visits

Month and year	Calgary SCS client visits	Drug poisoning deaths in Calgary
Jan-18	2054	31
Feb-18	2281	27
Mar-18	3134	33
Apr-18	3425	32
May-18	5102	40
Jun-18	4327	28
Jul-18	4151	29
Aug-18	4332	37
Sep-18	5065	28
Oct-18	6204	28
Nov-18	5858	28
Dec-18	5989	38
Jan-19	6060	28
Feb-19	4950	20
Mar-19	5613	26
Apr-19	5959	27
May-19	5442	22
Jun-19	5293	37
Jul-19	5942	35
Aug-19	5798	16
Sep-19	5140	26
Oct-19	6183	22
Nov-19	6112	16
Dec-19	6536	16
Jan-20	6623	18
Feb-20	6598	22
Mar-20	5850	25
Apr-20	4440	34
May-20	4117	44
Jun-20	3978	47
Jul-20	3444	53
Aug-20	3526	39
Sep-20	3669	39
Oct-20	3850	44
Nov-20	3852	44
Dec-20	3778	46
Jan-21	3865	43
Feb-21	3340	35
Mar-21	4083	50
Apr-21	4073	39
May-21	4073	52
Jun-21	3478	47
Jul-21	3280	41
Aug-21	3465	42
Sep-21	3045	53
Oct-21	3287	51
Nov-21	3055	64
Dec-21	3089	59
Jan-22	2893	63
Feb-22	3014	65
Mar-22	3531	43
Apr-22	3210	35
May-22	3214	40
Jun-22	3210	37
Jul-22	3914	38
Aug-22	3353	46
Sep-22	3182	36
Oct-22	3495	49
Nov-22	3443	40
Dec-22	3245	55
Jan-23	3163	55
Feb-23	3061	51
Mar-23	3180	62
Apr-23	3050	76
May-23	2730	69
Jun-23	2774	72
Jul-23	3066	59
Aug-23	2793	55
Sep-23	2729	36
Oct-23	3044	44
Nov-23	2990	43
Dec-23	3292	48

C. Scatterplots of drug poisoning deaths in Calgary as a function of Calgary SCS: drug consumption events

Month and year	Calgary SCS drug consumption events	Drug poisoning deaths in Calgary
Jan-18	1687	31
Feb-18	2003	27
Mar-18	2683	33
Apr-18	2867	32
May-18	4131	40
Jun-18	3545	28
Jul-18	3295	29
Aug-18	3571	37
Sep-18	4162	28
Oct-18	4664	28
Nov-18	4745	28
Dec-18	5033	38
Jan-19	4936	28
Feb-19	3877	20
Mar-19	4409	26
Apr-19	5309	27
May-19	4942	22
Jun-19	4532	37
Jul-19	4804	35
Aug-19	4928	16
Sep-19	4361	26
Oct-19	5311	22
Nov-19	5420	16
Dec-19	5800	16
Jan-20	5994	18
Feb-20	6069	22
Mar-20	5538	25
Apr-20	3988	34
May-20	3537	44
Jun-20	3382	47
Jul-20	2965	53
Aug-20	3003	39
Sep-20	3210	39
Oct-20	3427	44
Nov-20	3555	44
Dec-20	3467	46
Jan-21	3580	43
Feb-21	3052	35
Mar-21	3616	50
Apr-21	3594	39
May-21	3540	52
Jun-21	2862	47
Jul-21	2611	41
Aug-21	2875	42
Sep-21	2518	53
Oct-21	2891	51
Nov-21	2636	64
Dec-21	2692	59
Jan-22	2518	63
Feb-22	2669	65
Mar-22	3115	43
Apr-22	2853	35
May-22	2717	40
Jun-22	2751	37
Jul-22	3162	38
Aug-22	2758	46
Sep-22	2615	36
Oct-22	3019	49
Nov-22	3014	40
Dec-22	2806	55
Jan-23	2624	55
Feb-23	2548	51
Mar-23	2684	62
Apr-23	2539	76
May-23	2139	69
Jun-23	2031	72
Jul-23	2431	59
Aug-23	2185	55
Sep-23	2192	36
Oct-23	2609	44
Nov-23	2606	43
Dec-23	2759	48

D. Scatterplots of drug poisoning deaths in Calgary as a function of Calgary SCS: drug poisoning events

Month and year	Overdoses reported at Calgary SCS	Drug poisoning deaths in Calgary
Jan-18	35	31
Feb-18	29	27
Mar-18	67	33
Apr-18	44	32
May-18	71	40
Jun-18	78	28
Jul-18	67	29
Aug-18	59	37
Sep-18	89	28
Oct-18	63	28
Nov-18	62	28
Dec-18	52	38
Jan-19	60	28
Feb-19	70	20
Mar-19	53	26
Apr-19	38	27
May-19	63	22
Jun-19	57	37
Jul-19	90	35
Aug-19	64	16
Sep-19	39	26
Oct-19	49	22
Nov-19	73	16
Dec-19	71	16
Jan-20	47	18
Feb-20	54	22
Mar-20	83	25
Apr-20	87	34
May-20	52	44
Jun-20	42	47
Jul-20	63	53
Aug-20	50	39
Sep-20	82	39
Oct-20	81	44
Nov-20	78	44
Dec-20	69	46
Jan-21	104	43
Feb-21	89	35
Mar-21	104	50
Apr-21	85	39
May-21	138	52
Jun-21	136	47
Jul-21	146	41
Aug-21	131	42
Sep-21	189	53
Oct-21	176	51
Nov-21	164	64
Dec-21	214	59
Jan-22	172	63
Feb-22	148	65
Mar-22	120	43
Apr-22	101	35
May-22	90	40
Jun-22	103	37
Jul-22	87	38
Aug-22	68	46
Sep-22	67	36
Oct-22	119	49
Nov-22	130	40
Dec-22	165	55
Jan-23	137	55
Feb-23	126	51
Mar-23	226	62
Apr-23	210	76
May-23	143	69
Jun-23	140	72
Jul-23	139	59
Aug-23	174	55
Sep-23	158	36
Oct-23	182	44
Nov-23	211	43
Dec-23	218	48

E. Scatterplots of drug poisoning deaths in Calgary as a function of Calgary SCS: drug poisoning events (%)

Month and year	Calgary SCS poisoning rate (%)	Drug poisoning deaths in Calgary
Jan-18	2.07	31
Feb-18	1.45	27
Mar-18	2.5	33
Apr-18	1.53	32
May-18	1.72	40
Jun-18	2.2	28
Jul-18	2.03	29
Aug-18	1.65	37
Sep-18	2.14	28
Oct-18	1.35	28
Nov-18	1.31	28
Dec-18	1.03	38
Jan-19	1.22	28
Feb-19	1.81	20
Mar-19	1.2	26
Apr-19	0.72	27
May-19	1.27	22
Jun-19	1.26	37
Jul-19	1.87	35
Aug-19	1.3	16
Sep-19	0.89	26
Oct-19	0.92	22
Nov-19	1.35	16
Dec-19	1.22	16
Jan-20	0.78	18
Feb-20	0.89	22
Mar-20	1.5	25
Apr-20	2.18	34
May-20	1.47	44
Jun-20	1.24	47
Jul-20	2.12	53
Aug-20	1.67	39
Sep-20	2.55	39
Oct-20	2.36	44
Nov-20	2.19	44
Dec-20	1.99	46
Jan-21	2.91	43
Feb-21	2.92	35
Mar-21	2.88	50
Apr-21	2.37	39
May-21	3.9	52
Jun-21	4.75	47
Jul-21	5.59	41
Aug-21	4.56	42
Sep-21	7.51	53
Oct-21	6.09	51
Nov-21	6.22	64
Dec-21	7.95	59
Jan-22	6.83	63
Feb-22	5.55	65
Mar-22	3.85	43
Apr-22	3.54	35
May-22	3.31	40
Jun-22	3.74	37
Jul-22	2.75	38
Aug-22	2.47	46
Sep-22	2.56	36
Oct-22	3.94	49
Nov-22	4.31	40
Dec-22	5.88	55
Jan-23	5.22	55
Feb-23	4.95	51
Mar-23	8.42	62
Apr-23	8.27	76
May-23	6.68	69
Jun-23	6.89	72
Jul-23	5.71	59
Aug-23	7.96	55
Sep-23	7.21	36
Oct-23	6.98	44
Nov-23	8.09	43
Dec-23	7.9	48

Abbreviation: SCS, supervised consumption site.
Notes: (A) Monthly number of drug consumption events (grey) and drug poisoning events (red) recorded at Calgary SCS from January 2018 to December 2023, overlaid with the Calgary SCS poisoning events expressed as the percentage of drug poisoning events relative to drug consumption events (red circles; right y-axis). (B–E) Scatterplots of drug poisoning deaths in Calgary as a function of Calgary SCS (B) client visits, (C) drug consumption events, (D) drug poisoning events and (E) drug poisoning events (%). Individual data points correspond to monthly data collected from January 2018 to December 2023. Regression lines were fitted using a generalized linear model and error bars indicate 95% confidence intervals. Associations were assessed with Spearman’s correlation, with the rho (ρ) value and p value indicated above each scatterplot.
(B) Spearman rho = −0.6717; **** p < 0.0001; (C) Spearman rho = −0.6662; **** p < 0.0001; (D) Spearman rho = 0.6993; **** p < 0.0001; (E) Spearman rho = 0.7821; **** p < 0.0001

Association between drug poisoning deaths in Alberta and Calgary SCS utilization

The municipality of Calgary and the province of Alberta showed similar monthly patterns of drug deaths and drug death rates per 100 000 from 2018 to 2023 (Figure 3A). The frequency of drug poisoning events under supervised consumption at Calgary SCS strongly correlated with total monthly drug deaths in Alberta (ρ = 0.88, p < 0.0001; Figure 3B), even when data from the Calgary municipality were removed (ρ = 0.86, p < 0.0001; Figure 3C).

Figure 3: Descriptive text

A. Monthly drug poisoning events in Calgary (red) and Alberta, not including Calgary (pink) from January 2018 to December 2023, overlaid with the drug death rate in Calgary (red circle; right y-axis) or Alberta (pink triangle, right y-axis)

Month and year	Drug Poisoning Deaths in Calgary	Drug Poisoning Deaths in Alberta (outside of Calgary)	Drug Poisoning Death Rate in Alberta	Drug Poisoning Death Rate in Calgary
Jan-18	31	46	21.5	27.9
Feb-18	27	46	20.4	24.3
Mar-18	33	44	21.5	29.7
Apr-18	32	44	21.2	28.8
May-18	40	62	28.5	35.9
Jun-18	28	45	20.4	25.2
Jul-18	29	51	22.4	26.1
Aug-18	37	51	24.6	33.3
Sep-18	28	45	20.4	25.2
Oct-18	28	45	20.4	25.2
Nov-18	28	46	20.7	25.2
Dec-18	38	52	25.2	34.2
Jan-19	28	45	20.1	24.7
Feb-19	20	44	17.6	17.6
Mar-19	26	41	18.5	22.9
Apr-19	27	38	17.9	23.8
May-19	22	53	20.7	19.4
Jun-19	37	53	24.8	32.6
Jul-19	35	48	22.9	30.9
Aug-19	16	28	12.1	14.1
Sep-19	26	46	19.8	22.9
Oct-19	22	34	15.4	19.4
Nov-19	16	45	16.8	14.1
Dec-19	16	34	13.8	14.1
Jan-20	18	50	18.5	15.6
Feb-20	22	35	15.5	19.1
Mar-20	25	58	22.6	21.7
Apr-20	34	67	27.5	29.5
May-20	44	102	39.8	38.2
Jun-20	47	95	38.7	40.8
Jul-20	53	112	44.9	46.1
Aug-20	39	87	34.3	33.9
Sep-20	39	86	34	33.9
Oct-20	44	75	32.4	38.2
Nov-20	44	89	36.2	38.2
Dec-20	46	97	38.9	40
Jan-21	43	107	40.6	37
Feb-21	35	86	32.8	30.2
Mar-21	50	92	38.5	43.1
Apr-21	39	100	37.6	33.6
May-21	52	96	40.1	44.8
Jun-21	47	105	41.2	40.5
Jul-21	41	107	40.1	35.3
Aug-21	42	107	40.3	36.2
Sep-21	53	123	47.7	45.7
Oct-21	51	125	47.7	43.9
Nov-21	64	128	52	55.1
Dec-21	59	134	52.3	50.8
Jan-22	63	115	47.4	52.8
Feb-22	65	123	50	54.5
Mar-22	43	100	38	36.1
Apr-22	35	103	36.7	29.4
May-22	40	101	37.5	33.5
Jun-22	37	89	33.5	31
Jul-22	38	87	33.3	31.9
Aug-22	46	80	33.5	38.6
Sep-22	36	104	37.2	30.2
Oct-22	49	98	39.1	41.1
Nov-22	40	100	37.2	33.5
Dec-22	55	116	45.5	46.1
Jan-23	55	83	35.3	43.6
Feb-23	51	122	44.2	40.5
Mar-23	62	127	48.3	49.2
Apr-23	76	124	51.1	60.3
May-23	69	107	45	54.8
Jun-23	72	115	47.8	57.1
Jul-23	59	134	49.3	46.8
Aug-23	55	126	46.3	43.6
Sep-23	36	122	40.4	28.6
Oct-23	44	114	40.4	34.9
Nov-23	43	109	38.8	34.1
Dec-23	48	116	41.9	38.1

B. Scatterplot of drug deaths in Alberta as a function of Calgary SCS poisoning events per client visit (%)

Month and year	Calgary SCS poisoning events per client visit (%)	Drug Poisoning Deaths in Alberta
Jan-18	2.07	77
Feb-18	1.45	73
Mar-18	2.5	77
Apr-18	1.53	76
May-18	1.72	102
Jun-18	2.2	73
Jul-18	2.03	80
Aug-18	1.65	88
Sep-18	2.14	73
Oct-18	1.35	73
Nov-18	1.31	74
Dec-18	1.03	90
Jan-19	1.22	73
Feb-19	1.81	64
Mar-19	1.2	67
Apr-19	0.72	65
May-19	1.27	75
Jun-19	1.26	90
Jul-19	1.87	83
Aug-19	1.3	44
Sep-19	0.89	72
Oct-19	0.92	56
Nov-19	1.35	61
Dec-19	1.22	50
Jan-20	0.78	68
Feb-20	0.89	57
Mar-20	1.5	83
Apr-20	2.18	101
May-20	1.47	146
Jun-20	1.24	142
Jul-20	2.12	165
Aug-20	1.67	126
Sep-20	2.55	125
Oct-20	2.36	119
Nov-20	2.19	133
Dec-20	1.99	143
Jan-21	2.91	150
Feb-21	2.92	121
Mar-21	2.88	142
Apr-21	2.37	139
May-21	3.9	148
Jun-21	4.75	152
Jul-21	5.59	148
Aug-21	4.56	149
Sep-21	7.51	176
Oct-21	6.09	176
Nov-21	6.22	192
Dec-21	7.95	193
Jan-22	6.83	178
Feb-22	5.55	188
Mar-22	3.85	143
Apr-22	3.54	138
May-22	3.31	141
Jun-22	3.74	126
Jul-22	2.75	125
Aug-22	2.47	126
Sep-22	2.56	140
Oct-22	3.94	147
Nov-22	4.31	140
Dec-22	5.88	171
Jan-23	5.22	138
Feb-23	4.95	173
Mar-23	8.42	189
Apr-23	8.27	200
May-23	6.68	176
Jun-23	6.89	187
Jul-23	5.71	193
Aug-23	7.96	181
Sep-23	7.21	158
Oct-23	6.98	158
Nov-23	8.09	152
Dec-23	7.9	164

C. Scatterplot of drug deaths in Alberta (Calgary excluded) as a function of Calgary SCS poisoning events per client visit (%)

Month and year	Calgary SCS poisoning events per client visit (%)	Drug Poisoning Deaths in Alberta (outside of Calgary)
Jan-18	2.07	46
Feb-18	1.45	46
Mar-18	2.5	44
Apr-18	1.53	44
May-18	1.72	62
Jun-18	2.2	45
Jul-18	2.03	51
Aug-18	1.65	51
Sep-18	2.14	45
Oct-18	1.35	45
Nov-18	1.31	46
Dec-18	1.03	52
Jan-19	1.22	45
Feb-19	1.81	44
Mar-19	1.2	41
Apr-19	0.72	38
May-19	1.27	53
Jun-19	1.26	53
Jul-19	1.87	48
Aug-19	1.3	28
Sep-19	0.89	46
Oct-19	0.92	34
Nov-19	1.35	45
Dec-19	1.22	34
Jan-20	0.78	50
Feb-20	0.89	35
Mar-20	1.5	58
Apr-20	2.18	67
May-20	1.47	102
Jun-20	1.24	95
Jul-20	2.12	112
Aug-20	1.67	87
Sep-20	2.55	86
Oct-20	2.36	75
Nov-20	2.19	89
Dec-20	1.99	97
Jan-21	2.91	107
Feb-21	2.92	86
Mar-21	2.88	92
Apr-21	2.37	100
May-21	3.9	96
Jun-21	4.75	105
Jul-21	5.59	107
Aug-21	4.56	107
Sep-21	7.51	123
Oct-21	6.09	125
Nov-21	6.22	128
Dec-21	7.95	134
Jan-22	6.83	115
Feb-22	5.55	123
Mar-22	3.85	100
Apr-22	3.54	103
May-22	3.31	101
Jun-22	3.74	89
Jul-22	2.75	87
Aug-22	2.47	80
Sep-22	2.56	104
Oct-22	3.94	98
Nov-22	4.31	100
Dec-22	5.88	116
Jan-23	5.22	83
Feb-23	4.95	122
Mar-23	8.42	127
Apr-23	8.27	124
May-23	6.68	107
Jun-23	6.89	115
Jul-23	5.71	134
Aug-23	7.96	126
Sep-23	7.21	122
Oct-23	6.98	114
Nov-23	8.09	109
Dec-23	7.9	116

Abbreviation: SCS, supervised consumption site.
Notes: (A) Monthly drug poisoning events in Calgary (red) and Alberta, not including Calgary (pink) from January 2018 to December 2023, overlaid with the drug death rate in Calgary (red circle; right y-axis) or Alberta (pink triangle, right y-axis). (B) Scatterplot of drug deaths in Alberta as a function of Calgary SCS poisoning events per client visit (%). (C) Scatterplot of drug deaths in Alberta (Calgary excluded) as a function of Calgary SCS poisoning events per client visit (%). Individual data points correspond to monthly data collected from January 2018 to December 2023. Regression lines were fitted using a generalized linear model and error bars indicate 95% confidence intervals. Associations were assessed with Spearman’s correlation, with the rho (ρ) value and p value indicated above each scatterplot.
(B) Spearman rho = 0.8704; **** p < 0.0001; (C) Spearman rho = 0.8578; **** p < 0.0001

Association between drug poisoning deaths and EMS dispatches in Alberta

Across Alberta during the study period, there was a monthly average of 1854 EMS dispatches for drug poisoning events at a rate of 5.4% of the total EMS dispatches (Table 1). EMS dispatches for drug poisoning events peaked in 2022 with a monthly average of 2493 dispatches for drug poisoning events (6.7% of total EMS dispatches, Table 1). Provincial drug poisoning deaths across the study period positively correlated with total EMS dispatches (ρ = 0.75, p < 0.0001; Figure 4C) and EMS dispatches for opioid-related events (ρ = 0.91, p < 0.0001; Figure 4D).

Figure 4: Descriptive text

A. Monthly EMS dispatches for emergency events (grey bars; left y-axis) overlaid with EMS dispatches for drug poisoning events expressed as a percentage of total EMS emergency events (red diamonds; right y-axis) across Alberta from January 2018 to March 2023

Month and year	Total EMS Emergency Events	EMS responses to drug poisoning events per total emergency events (%)
Jan-18	30826	3.905794
Feb-18	27374	3.8869
Mar-18	30076	4.25921
Apr-18	28368	4.029188
May-18	30405	4.374281
Jun-18	30208	4.59812
Jul-18	30978	4.687197
Aug-18	30218	4.831557
Sep-18	28186	4.874761
Oct-18	30258	4.626876
Nov-18	29930	4.35015
Dec-18	31443	3.937283
Jan-19	30655	3.859077
Feb-19	27480	3.813683
Mar-19	30627	4.166259
Apr-19	29575	3.915469
May-19	31689	4.272776
Jun-19	31192	4.392152
Jul-19	31836	4.34728
Aug-19	31237	3.892819
Sep-19	30758	3.579557
Oct-19	30964	3.316755
Nov-19	30572	3.395264
Dec-19	32752	3.450171
Jan-20	32625	3.291954
Feb-20	29797	3.49364
Mar-20	31686	3.856593
Apr-20	29022	4.951416
May-20	30889	5.843504
Jun-20	31765	5.842909
Jul-20	35309	5.686935
Aug-20	34259	5.23658
Sep-20	32198	5.304677
Oct-20	32407	5.125436
Nov-20	31983	5.696776
Dec-20	33511	5.332577
Jan-21	32290	5.283369
Feb-21	29487	5.365076
Mar-21	32930	5.666565
Apr-21	33567	5.380284
May-21	36294	6.0313
Jun-21	38074	6.939119
Jul-21	41174	7.59217
Aug-21	38746	7.195581
Sep-21	38033	7.343623
Oct-21	36714	7.449474
Nov-21	36166	7.321794
Dec-21	38666	7.657891
Jan-22	38929	6.827815
Feb-22	33590	8.002382
Mar-22	36705	7.682877
Apr-22	36587	6.42578
May-22	37570	6.350812
Jun-22	36720	6.830065
Jul-22	39523	6.573388
Aug-22	38072	6.188275
Sep-22	36454	6.021287
Oct-22	37725	5.969516
Nov-22	37547	5.971183
Dec-22	38903	7.351618
Jan-23	36966	7.193096
Feb-23	33428	8.427067
Mar-23	37917	9.143656

B. Monthly EMS dispatches for opioid-related events (blue bars; left y-axis) overlaid with the drug poisoning death rate in Alberta (deaths per 100 000; black squares; right y-axis) from January 2018 to March 2023

Month and year	EMS responses to drug poisoning events	Drug poisoning deaths in Alberta per 100 000
Jan-18	1204	21.5
Feb-18	1064	20.4
Mar-18	1281	21.5
Apr-18	1143	21.2
May-18	1330	28.5
Jun-18	1389	20.4
Jul-18	1452	22.4
Aug-18	1460	24.6
Sep-18	1374	20.4
Oct-18	1400	20.4
Nov-18	1302	20.7
Dec-18	1238	25.2
Jan-19	1183	20.1
Feb-19	1048	17.6
Mar-19	1276	18.5
Apr-19	1158	17.9
May-19	1354	20.7
Jun-19	1370	24.8
Jul-19	1384	22.9
Aug-19	1216	12.1
Sep-19	1101	19.8
Oct-19	1027	15.4
Nov-19	1038	16.8
Dec-19	1130	13.8
Jan-20	1074	18.5
Feb-20	1041	15.5
Mar-20	1222	22.6
Apr-20	1437	27.5
May-20	1805	39.8
Jun-20	1856	38.7
Jul-20	2008	44.9
Aug-20	1794	34.3
Sep-20	1708	34
Oct-20	1661	32.4
Nov-20	1822	36.2
Dec-20	1787	38.9
Jan-21	1706	40.6
Feb-21	1582	32.8
Mar-21	1866	38.5
Apr-21	1806	37.6
May-21	2189	40.1
Jun-21	2642	41.2
Jul-21	3126	40.1
Aug-21	2788	40.3
Sep-21	2793	47.7
Oct-21	2735	47.7
Nov-21	2648	52
Dec-21	2961	52.3
Jan-22	2658	47.4
Feb-22	2688	50
Mar-22	2820	38
Apr-22	2351	36.7
May-22	2386	37.5
Jun-22	2508	33.5
Jul-22	2598	33.3
Aug-22	2356	33.5
Sep-22	2195	37.2
Oct-22	2252	39.1
Nov-22	2242	37.2
Dec-22	2860	45.5
Jan-23	2659	35.3
Feb-23	2817	44.2
Mar-23	3467	48.3

C. Scatterplots of Alberta drug deaths as a function of province-wide: total EMS response

Month and year	Total EMS responses	Drug Poisoning Deaths in Alberta
Jan-18	30826	77
Feb-18	27374	73
Mar-18	30076	77
Apr-18	28368	76
May-18	30405	102
Jun-18	30208	73
Jul-18	30978	80
Aug-18	30218	88
Sep-18	28186	73
Oct-18	30258	73
Nov-18	29930	74
Dec-18	31443	90
Jan-19	30655	73
Feb-19	27480	64
Mar-19	30627	67
Apr-19	29575	65
May-19	31689	75
Jun-19	31192	90
Jul-19	31836	83
Aug-19	31237	44
Sep-19	30758	72
Oct-19	30964	56
Nov-19	30572	61
Dec-19	32752	50
Jan-20	32625	68
Feb-20	29797	57
Mar-20	31686	83
Apr-20	29022	101
May-20	30889	146
Jun-20	31765	142
Jul-20	35309	165
Aug-20	34259	126
Sep-20	32198	125
Oct-20	32407	119
Nov-20	31983	133
Dec-20	33511	143
Jan-21	32290	150
Feb-21	29487	121
Mar-21	32930	142
Apr-21	33567	139
May-21	36294	148
Jun-21	38074	152
Jul-21	41174	148
Aug-21	38746	149
Sep-21	38033	176
Oct-21	36714	176
Nov-21	36166	192
Dec-21	38666	193
Jan-22	38929	178
Feb-22	33590	188
Mar-22	36705	143
Apr-22	36587	138
May-22	37570	141
Jun-22	36720	126
Jul-22	39523	125
Aug-22	38072	126
Sep-22	36454	140
Oct-22	37725	147
Nov-22	37547	140
Dec-22	38903	171
Jan-23	36966	138
Feb-23	33428	173
Mar-23	37917	189

D. Scatterplots of Alberta drug deaths as a function of province-wide: EMS responses for opioid-related events

Month and year	EMS responses to opioid-related events	Drug poisoning deaths in Alberta
Jan-18	1204	77
Feb-18	1064	73
Mar-18	1281	77
Apr-18	1143	76
May-18	1330	102
Jun-18	1389	73
Jul-18	1452	80
Aug-18	1460	88
Sep-18	1374	73
Oct-18	1400	73
Nov-18	1302	74
Dec-18	1238	90
Jan-19	1183	73
Feb-19	1048	64
Mar-19	1276	67
Apr-19	1158	65
May-19	1354	75
Jun-19	1370	90
Jul-19	1384	83
Aug-19	1216	44
Sep-19	1101	72
Oct-19	1027	56
Nov-19	1038	61
Dec-19	1130	50
Jan-20	1074	68
Feb-20	1041	57
Mar-20	1222	83
Apr-20	1437	101
May-20	1805	146
Jun-20	1856	142
Jul-20	2008	165
Aug-20	1794	126
Sep-20	1708	125
Oct-20	1661	119
Nov-20	1822	133
Dec-20	1787	143
Jan-21	1706	150
Feb-21	1582	121
Mar-21	1866	142
Apr-21	1806	139
May-21	2189	148
Jun-21	2642	152
Jul-21	3126	148
Aug-21	2788	149
Sep-21	2793	176
Oct-21	2735	176
Nov-21	2648	192
Dec-21	2961	193
Jan-22	2658	178
Feb-22	2688	188
Mar-22	2820	143
Apr-22	2351	138
May-22	2386	141
Jun-22	2508	126
Jul-22	2598	125
Aug-22	2356	126
Sep-22	2195	140
Oct-22	2252	147
Nov-22	2242	140
Dec-22	2860	171
Jan-23	2659	138
Feb-23	2817	173
Mar-23	3467	189

Abbreviation: EMS, emergency medical services.
Notes: EMS dispatches positively correlate with drug deaths in Alberta from 2018 to 2023. (A) Monthly EMS dispatches for emergency events (grey bars; left y-axis) overlaid with EMS dispatches for drug poisoning events expressed as a percentage of total EMS emergency events (red diamonds; right y-axis) across Alberta from January 2018 to March 2023. (B) Monthly EMS dispatches for opioid-related events (blue bars; left y-axis) overlaid with the drug poisoning death rate in Alberta (deaths per 100 000; black squares; right y-axis) from January 2018 to March 2023. (C–D) Scatterplots of Alberta drug deaths as a function of province-wide (C) total EMS responses and (D) EMS responses for opioid-related events. Individual data points correspond to monthly data collected from January 2018 to March 2023, with symbols representing different years. Regression lines were fitted using a generalized linear model and error bars indicate 95% confidence intervals. Associations were assessed with Spearman’s correlation, with the rho (ρ) value and p value indicated above each scatterplot.
(C) Spearman rho = 0.7490; **** p < 0.0001; (D) Spearman rho = 0.9068; **** p < 0.0001

Multiple linear regression analysis

Overall total visits and total visits where drugs were consumed at the Calgary SCS were both associated with decreases in drug deaths in the province (β = −.03, 95% CI: −0.032 to −0.019; β = −.03, 95% CI: −0.035 to −0.020, respectively). However, increases in drug poisoning events at Calgary SCS were associated with increases in broader drug death rates in the province (β = .73, 95% CI: 0.57–0.88). An association was also found between Alberta-wide EMS dispatches for opioid-related events and drug deaths (β = .06, 95% CI: 0.05–0.06), suggesting EMS dispatches for opioid-related events mirror drug deaths in the province (Figures 1 and 2). Total dispatches (including for non-opioid related events) were associated with marginal increases in drug deaths (β = 0.01, 95% CI: 0.007–0.011; β = .01, 95% CI: 0.010–0.016, respectively) (Table 3).

Table 3. Regression coefficients showing associations between Calgary SCS utilization and EMS dispatches on drug poisoning deaths in Alberta

Measure	Category	β coefficient (95% CI)Footnote a
Calgary SCS utilization	Total visits	−0.025 (−0.032, −0.019)
	Total visits with drug consumption	−0.028 (−0.035, −0.020)
	Total drug poisoning events	0.727 (0.574, 0.879)
	Poisoning rate	0.136 (0.125, 0.146)
EMS dispatches	Total	0.009 (0.007, 0.011)
	Opioid-related	0.057 (0.050, 0.064)
	Not opioid-related	0.013 (0.010, 0.016)

Discussion

Our analysis suggests that both EMS and SCS drug poisoning event data may serve as potential proxies to understand drug deaths in Alberta. We found significant positive correlations between monthly SCS drug poisoning events and provincial drug poisoning deaths, monthly SCS drug poisoning events and Calgary drug poisoning deaths, and EMS dispatches for opioid-related events and provincial drug poisoning deaths. Interestingly, although not an initial objective of the study, we found that total SCS visits were significantly negatively correlated with provincial drug poisoning deaths. Findings from the multiple linear regression also suggests that increased SCS drug poisoning events are significantly associated with provincial drug poisoning deaths. Using these alternative forecasting methods can help service providers, people who use drugs and their families to respond to changes in the drug supply, potentially preventing deaths. This is particularly important in Alberta, where public drug death reporting is delayed for several months and remains inaccurate for many months after release. The results also highlight an inverse relationship between provincial drug deaths and both total client visits and Calgary SCS visits where drugs were consumed. This finding agrees with previous research linking SCS access to prevention of drug toxicity deaths.^{Footnote 22}

Unpublished data held by the Alberta government and Recovery Alberta, the health authority that operates SCSs, also suggest that regular clients of SCSs have approximately half the number of hospitalizations for substance use–related incidents, including drug poisoning, than people who use drugs but do not attend SCSs regularly.^{Footnote 32} Hospitalizations of regular SCS clients show approximately half the duration of less-regular clients, indicating lower severity of medical distress. The data also reveal that supervised consumption clients in Alberta have two- to four-fold higher opioid agonist treatment (OAT) initiation than non-clients who use drugs.^{Footnote 32}

Our analysis illustrates a rise in drug deaths across Alberta from 2018 to 2023 that coincided with a decrease in SCS visits from 2020 to 2023. In Alberta at the onset of the pandemic (2020 Q2), SCS utilization fell sharply in all sites, which coincided with a steep rise in the frequency of drug poisoning events per client visit to the sites. The rate at which drug poisoning events occurred under supervised consumption followed similar trends across sites in Alberta, indicating that the provincial drug supply was experiencing relatively similar volatility through this period. Several short-lived outliers in drug poisoning frequency under supervised consumption (e.g. Calgary from Q3 to Q4, 2021; Grande Prairie Q3, 2023) may indicate geographically limited perturbations in the drug supply during those periods. These findings coincide with existing research that shows drug poisoning events increased in Canada during COVID due to a combination of increasing supply toxicity and changes to service access due to public health measures.^{Footnote 12} We observed declining SCS utilization over the study period, which may be explained by the closure of SCSs across the province.^{Footnote 33Footnote 34Footnote 35} Shifts to inhalation drug use and related unmet service needs may also inform SCS utilization.^{Footnote 36Footnote 37Footnote 38Footnote 39} Given international evidence of effectiveness and our finding that SCS visits were significantly associated with decreased drug deaths, it is imperative that SCSs are funded to meet population needs as part of the response to increasingly volatile unregulated drug supplies.^{Footnote 40}

To our knowledge, this is the first study to use province-wide EMS and SCS data to understand trends in provincial drug deaths. It provides further validation for the Ottawa study that used municipal EMS data to predict drug deaths.^{Footnote 21} Our findings also suggest that EMS dispatch data can be used to understand drug deaths despite changes to the drug supply. This supports findings from a descriptive study from the United States that concluded that monitoring drug poisoning-related EMS data can provide “real-time” insight into drug poisoning trends.^{Footnote 41} Our finding that SCS visits are significantly associated with decreased drug poisoning deaths is consistent with previous research that showed decreased drug deaths in neighbourhoods where SCSs were implemented.^{Footnote 22} Our findings contribute to growing knowledge on the association between SCSs and drug deaths, making use of SCS data that could specifically highlight changes in the drug supply.

Strengths and limitations

Our focus on a single province where EMS data are reported consistently lends rigour to our research. This study uses routinely collected and accessible sources of data on SCSs and drug poisoning in Alberta, including provincial EMS dispatch data. A previous Canadian report attempted to estimate the number of EMS dispatches in response to opioid-related events; however, variance in how EMS data are reported can be a limitation.^{Footnote 42Footnote 43} EMS records could be misclassified, as drug poisoning emergency events are recorded by paramedics but not toxicologically confirmed. Meanwhile, emergency events that are resolved on-site and do not involve transfer to a hospital, such as events responded to by outreach workers or fire departments, would not be captured in these data. Caution should be taken in applying EMS data from the study period to current events, because the relationship between drug poisoning fatalities and EMS dispatches may diverge as tranquilizers become more prevalent in unregulated drug supplies, including Alberta. To date, provinces including British Columbia, Ontario and Saskatchewan have issued public health warnings around increasing non-fatal poisonings related to tranquilizers, while Alberta has not.^{Footnote 44Footnote 45Footnote 46}

Most of our SCS analysis focused on data from one site in Calgary, because there were limited SCS data available from the other sites during the study period. In 2024, detailed monthly reports from the Calgary site were removed from public access. From then on, only quarterly data were available from provincial sites, and these lacked critical details captured in the earlier Calgary data, such as the number of consumption events. The number of site visits at Calgary SCS comprises 20% to 85% of the total site visits across Alberta during the study period; the large variation in these percentages can be attributed to few SCS being operational in 2018 and various site closures from 2020 onward. Although the SCS may reflect urban trends, we recognize that these data may not reflect trends in other urban and rural areas of the province, given that there are differences in local drug supply in Alberta.^{Footnote 47} Residual confounding may also be a source of bias, considering that other variables associated with both EMS dispatches, SCS utilization, and drug deaths likely exist but were not available in the existing data. Given the ecological study design, we caution readers against equivalizing the current study risk estimates on individuals.

Future research should incorporate province-wide SCS data to provide a more comprehensive understanding of these relationships and validate our findings using data from other SCSs in Alberta or Canada. Researchers may consider assessing the correlation between EMS dispatches and drug deaths at a national level through the creation of a dependable case definition. Modelling differences based on gender, Indigeneity, and race would also be valuable, particularly given that key subpopulations are disproportionately affected by drug poisoning.

Conclusion

Our study found that EMS dispatch data and SCS drug-related event data can be used to understand drug deaths on a provincial level. This is valuable learning for communities who wish to understand trends in drug deaths to respond effectively to the toxic drug crisis. However, this method is not a replacement for timely and transparent death data. Provincial and territorial governments must provide publicly available data on the unregulated toxic drug crisis to guide urgent responses to this ongoing public health emergency.

Acknowledgements

There is no project-specific funding to report. HM was supported by a Pierre Elliott Trudeau Foundation Doctoral Scholarship and Izaak Walton Killam Memorial Scholarship. EH receives funding from the Canada Research Chairs program through a Tier 2 Canada Research Chair in Health Systems Innovation. The authors wish to acknowledge the help of the Canadian Research Initiative on Substance Use Matters (CRISM) Prairie Node and partners for their support with data acquisition.

Conflicts of interest

HM has received grants from Pierre Elliott Trudeau Foundation and Social Sciences and Humanities Research Council, speaker honorarium from Story Money Impact, travel support from Women and Children’s Health Research Institute and University of Alberta, and held a leadership role with Canadian Students for Sensible Drug Policy and Government of Canada Civil Society Working Group on UN Drug Policy. KVL has received grants from Canadian Institutes of Health Research, Natural Science and Engineering Research Council, University of Calgary, Alberta Children’s Health Research Institute, and Alberta Innovates, speaker honoraria from University of Calgary, and travel support from Alberta Innovates and Canadian Institutes of Health Research. ET (Author 3) held a board role with Alberta Alliance Who Educate and Advocate Responsibly, currently holds a board role with EACH+EVERY: Community Drug Poisoning Response, and is writer and editor for Drug Data Decoded. EH has received grants from Canada Foundation for Improvement, Royal Alexandra Hospital Foundation, Government of Alberta, and Alberta Health Services, consulting fees from Alberta Office of the Auditor General, and travel support from Canadian Institutes of Health Research, University of Toronto, and University of Alberta. CB and ET (Author 5) report no conflicts.

Authors’ contributions and statements

• HM: Conceptualization, methodology, data curation, writing—original draft, project administration.
• KVL: Conceptualization, methodology, data curation, data analysis, writing—original draft, visualization, project administration.
• ET (Author 3): Conceptualization, methodology, data curation, data analysis, writing—original draft, project administration.
• CB: Methodology, data analysis, writing—original draft.
• ET (Author 5): Writing—review and editing.
• EH: Supervision, resources, writing—review and editing.

The content and views expressed in this article are those of the authors and do not necessarily reflect those of the Government of Canada.

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