How does social support modify the association between psychological distress and risk of suicide death?

Social support (SS) has been reported as a factor preventing suicide death, but whether this association is independent of mental status is unclear. The present study examined the effect modification of SS on the association between psychological distress status and risk of suicide death.

Follow-up data for 43,015 subjects participating in a prospective cohort study were analyzed. At baseline, the subjects were asked about SS and mental status with the Kessler six-item Distress (K6) Scale. A Cox model was used to estimate the multivariate-adjusted hazard ratios (HRs) of suicide death according to two levels of psychological distress (K6 ≤ 4, K6 ≥ 5). The HRs in each SS subtype (emotional and instrumental) were also calculated.

There was a significant association between SS and a lower risk of suicide death in the stratum of K6 ≥ 5, with an HR of 0.58 (95% confidence interval, 0.35-0.96). On the other hand, the association with the K6 ≤ 4 strata was not significant.

SS appears to be associated with a lower risk of suicide death only among participants with moderate or severe psychological distress. These results imply that early detection of psychological distress and provision of SS is important for preventing suicide death.