Corrigendum – Supervised consumption sites and population-level overdose mortality: a systematic review of recent evidence, 2016–2024

This corrigendum is being published to add a clarification on page 361 of the following article:

Gariépy G, Prowse RKM, Plouffe R, Graham E. Supervised consumption sites and population-level overdose mortality: a systematic review of recent evidence, 2016–2024. Health Promot Chronic Dis Prev Can. 2025;45(9):357-66. https://doi.org/10.24095/hpcdp.45.9.02

Text has been added to highlight an important precision about the Rammohan et al. study^{Footnote 1}. Bold has been used to identify the added text.

The authors thank Dr. Daniel Werb for raising this concern.

Before correction

The two observational studies used ecological study designs to examine associations between SCSs and overdose mortality, one at the province level^{Footnote 33} and the other at the neighbourhood level.^{Footnote 34} In Alberta, a province-wide analysis found that higher SCS visits across the seven provincial SCSs correlated with fewer fentanyl-related overdose deaths between 2017 and 2020 (r = −0.64; p = 0.03).^{Footnote 33} A study in Toronto, Ontario, compared overdose mortality rates in 2017 and 2019, that is, before and after SCSs were implemented, at different distances from the sites.^{Footnote 34} Neighbourhoods within 500 m of an SCS had 67% fewer overdose deaths per 100 000 people (p = 0.04) after the SCSs had been implemented. Areas beyond 500 m of an SCS had 24% fewer deaths, but this difference was not statistically significant (p = 0.38).^{Footnote 34} Quality assessment found that both ecological studies had high risk of bias, primarily because of a lack of control for confounding factors (Additional File 3; available from the authors upon request).

After correction

The two observational studies used ecological study designs to examine associations between SCSs and overdose mortality, one at the province level^{Footnote 33} and the other at the neighbourhood level.^{Footnote 34} In Alberta, a province-wide analysis found that higher SCS visits across the seven provincial SCSs correlated with fewer fentanyl-related overdose deaths between 2017 and 2020 (r = −0.64; p = 0.03).^{Footnote 33} A study in Toronto, Ontario, compared overdose mortality rates in 2017 and 2019, that is, before and after SCSs were implemented, at different distances from the sites.^{Footnote 34} Neighbourhoods within 500 m of an SCS had 67% fewer overdose deaths per 100 000 people (p = 0.04) after the SCSs had been implemented. Areas beyond 500 m of an SCS had 24% fewer deaths, but this difference was not statistically significant (p = 0.38).^{Footnote 34} The study also conducted geographically weighted regression analyses of post-implementation spatial patterns, finding inverse associations between SCS proximity and overdose mortality that strengthened from 2018 to 2019. These analyses adjusted for neighbourhood-level sociodemographic factors and substance-use-related health services. Quality assessment found that both ecological studies had high risk of bias, primarily because of a lack of control for confounding factors (Additional File 3; available from the authors upon request).

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