Table 5. GRADE evidence profiles for SCFs.
| Certainty assessment | Summary of Findings | Certainty | Importance | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| № of studies | Study design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other considerations | ||||
| Outcome: Mortality | ||||||||||
| Lethal overdoses in SCF proximity (Source systematic review: Kennedy 2017; 1 observational trial) | ||||||||||
| 1 | Observational studies | Not serious | Not serious | Not serious | Not serious | None | 35% decrease in the number of lethal overdoses within 500 metres of the SCF from 253.8 (187.3 to 320.3) to 165.1 (108.8 to 221.4) deaths per 100,000 person-years (RD 88.7 (1.6 to 175.8) per 100 000 person years; p = 0.048), compared to the rest of the city: 9.3%, from 7·6 (6.2 to 9.0) to 6·9 (5.5 to 8.4) deaths per 100 000 person-years (p = 0·490). | ⨁⨁◯◯ LOW |
CRITICAL | |
| Lethal overdoses avoided each year (Source systematic review: Kennedy 2017; 2 observational trials) | ||||||||||
| 2 | Observational studies | Not serious | Not serious | Serious a | Not serious | None | In Vancouver, the SCF avoided 1004 overdoses over 4 years, including 453 life-threatening overdoses, suggesting that between 2 and 12 cases of lethal overdose might have been avoided each year. A study from Germany estimate that at least 10 deaths are prevented by SCF each year. | ⨁◯◯◯ VERY LOW |
CRITICAL | |
| Deaths during study period (Source systematic review: Kennedy 2017; 2 observational trials) | ||||||||||
| 2 | Observational studies | Not serious | Not serious | Not serious | Not serious | None | There were 336 reported overdoses within the SCF over a four year period, and no deaths. In another study, over a 17 month period, there were 409 overdoses and no deaths. | ⨁ ⨁◯◯ LOW |
CRITICAL | |
| Outcome: Morbidity | ||||||||||
| HIV cases averted (Source systematic review: Kennedy 2017; 2 observational trials) | ||||||||||
| 2 | Observational studies | Not serious | Serious | Serious a | Not serious | None | A mathematical simulation estimates that 1191 incident HIV cases were averted over 10 years. Another mathematical model estimated that the SCF prevents 22 incident HIV infections per year. | ⨁◯◯◯ VERY LOW |
CRITICAL | |
| HCV cases averted (Source systematic review: Kennedy 2017; 1 observational trial) | ||||||||||
| 1 | Observational studies | Not serious | Not serious | Serious a | Not serious | None | A mathematical simulation estimates that 54 incident HCV cases were averted over 10 years | ⨁◯◯◯ VERY LOW |
CRITICAL | |
| Outcome: Substance use | ||||||||||
| Injection drug use initiation (Source systematic review: Kennedy 2017; 1 observational trial) | ||||||||||
| 1 | Observational studies | Not serious | Not serious | Not serious | Not serious | None | Among the entire population of SCF users in Vancouver (n = ~ 5000), the estimated number who may have initiated injection drug use inside the SCF since the SIF opened was 5 (95% CI 2–12), which is comparatively lower than the expected rate of initiation into injection drug use among local street-involved youth during a similar follow-up period (100 initiations; 95% CI 81–122) | ⨁ ⨁◯◯ LOW |
CRITICAL | |
Explanations
a. Mathematical simulations providing indirect evidence