Background: Whether putative suicide risk factors, such as conduct and emotional disorders, are specific to suicide or are general associations of a continuum between subintentional and intentional self-destruction is not clear. We undertook an investigation of this issue in a UK population-based birth cohort.
Methods: Using competing-risks analysis, we examined links between prospectively collected childhood and adolescent temperamental and behavioural variables and the risk of natural, accidental, and suicidal death, occurring between the ages of 16 and 50 years. Of the 5362 members of the cohort, full data were available for 3591. A panel of psychiatrists scored deaths on likely suicidal intention. These scores were used in a weighted logistic regression to examine independence of risk factors for (sub)intentional self-destruction.
Findings: There were 167 deaths among the risk-set between the 16th and 50th birthdays. 120 were due to natural causes; of the other 47, the panel of psychiatrists judged that 36 were accidental deaths and 11 were suicides (certainty rating > or = 51%). Adolescent emotional instability and conduct problems had different associations with the various causes of premature death, being lowest for natural death (odds ratio 1.0 [95% CI 0.8-1.2] and 1.2 [1.0-1.5]), intermediate for accidental death (1.1 [0.8-1.5] and 1.3 [1.0-1.7]), and highest for suicidal death (2.0 [1.2-3.6] and 1.8 [1.3-2.5]). Emotional instability (boys 1.3 [1.0-1.7], girls 1.4 [1.0-1.9]) increased risk for subintentional or intentional self-destruction, as did low anxiety in adolescence (1.7 [1.3-2.5]) and nocturnal enuresis at age 4 (1.4 [1.2-1.7]) in boys, and conduct problems in girls (1.4 [1.0-2.0]).
Interpretation: Suicide shares important risk factors with other causes of premature death. These findings suggest an aetiological continuum of self-destruction from subintentional to intentional. Research on premature mortality associated with psychological disorder should include all causes of death.