Background: Suicide may be an extreme expression of liability to death of any type. If true, suicide risk factors should also increase other mortality, and, given exposure, excess risk should be higher for suicide than for other mortality.
Methods: Of 304 publications identified in Index Medicus (1966-June 1988) by the string (suicide) and (mortality or death) and (accidental or natural), 24 reported total and cause-specific mortality associated with exposure to 16 established suicide risk factors; reference scanning yielded 122 more. These 146 publications reported on 163 cohorts (total subjects = 1179 126) mortality. Meta-analysis gave random effects standardized mortality ratios (SMR) for natural, accidental and suicidal death, stratified over the 16 risk groups.
Results: Overall, SMR were 8.6 (95% CI : 7.1-10.4) for suicide, 3.4 (95% CI : 2.9-4.0) for accidental and 2.1 (95% CI : 1.9-2.3) for natural death. Compatible with the first hypothesis, in most groups, mortality of any type was raised. Supporting the second hypothesis, excesses increased from lowest for natural death to highest for suicide. This trend was most pronounced following deliberate self-harm, intermediate in substance abusers, and weakest, but present, in bereaved and low social class cohorts and reversed in smokers and epileptic people.
Conclusions: Many suicide risks apply to any type of premature death, whilst also retaining some specificity for suicide. Primary prevention, targeting such generic risk factors, will not only reduce rates of suicide but also of other types of death. Conversely, when prevention focuses on specific outcomes-such as suicide-only, other types of mortality may increase.