Table 5

Overall summary of findings

Intervention category	# of unique interventions (# of papers)	Pooled time period	High-level findings	Study quality assessment
Access to healthcare	1 (1)	1971–1989	One study reported both null and statistically significant effects for suicide prevention centres on reducing suicide rates among both men and women.	Weak^S1
Communication strategies	3 (4)	1946–2012	Two studies reported a statistically significant effect for communication strategies on reducing suicide mortality. Two studies reported null findings for the effect of communication strategies on reducing suicide mortality.	Weak to moderate 1 weak^S2 3 moderate^S3–S5
Community-based interventions	7 (9)	1986–2016	Two studies reported a statistically significant effect for community-based intervention on reducing suicide mortality, one study reported both null and statistically significant effects on reducing suicide mortality, one study reported both null and statistically significant effects on increasing suicide mortality and five studies reported null findings.	Weak to strong (largely moderate) 1 weak^S7 7 moderate^S8–S14 1 strong^S6
Law and regulation reform	29 (66)	1907–2017	Of the 21 law and regulation reforms, nine studies reported a statistically significant effect for reforms on reducing suicide mortality, seven showed mixed null and statistically significant effects on reducing suicide mortality, two showed mixed null and statistically significant effects on both increasing and decreasing suicide mortality, and three studies reported null findings. Of the 45 firearm law and regulation reform studies, 19 reported a statistically significant effect for reforms on reducing suicide mortality, eleven studies reported mixed null and statistically significant effects on reducing suicide mortality, five studies reported null and statistically significant effects on both reducing and increasing suicide mortality, and ten studies reported null findings.	Weak to strong (largely moderate to strong) 5 weak^{S56, S57, S60, S73, S74} 32 moderate^{S28–S31, S34, S36–S46, S49–S53, S58, S61, S64, S65, S67, S71, S75–S77, S79, S80} 29 strong^{S15–S27, S32, S33, S35, S47. S48, S54, S55, S59, S62, S63, S66, S68–S70, S72, S78}
Mental health policies and strategies	7 (7)	1980–2016	Two studies reported a statistically significant effect for mental health policies on reducing suicide mortality, four studies reported both null and significant effects on reducing suicide mortality and one study reported null findings.	Moderate to strong 3 moderate^{S82, S84, S85} 4 strong^{S81, S83, S86, S87}
Physical barriers	11 (13)	1988–2014	Eleven studies reported statistically significant effects for physical barriers on reducing suicide mortality, and two studies reported both null and statistically significant effects on reducing suicide mortality.	Moderate to strong (largely strong) 3 moderate^{S92, S94, S100} 10 strong^{S88–S91, S93, S95–S99}