Seasonal and socio-demographic predictors of suicide in Ireland: a 22 year study.

BACKGROUND Seasonal influences on suicide have been studied for many years with inconclusive and contradictory findings. METHODS Data on suicide in Ireland from 1980 to 2002 was examined to ascertain the contribution of season and demographic variables to suicide. Using Poisson regression modelling and sinusoidal analysis a small seasonal effect (7% from peak to trough) was identified but age, gender, marital status and residence were much larger contributors. The seasonal contribution increased in the latter half of the period under study. There was also a small seasonal effect for method of suicide. The suicide rate was highest in the 40-44 age group after controlling for confounders. LIMITATIONS Because this was an ecological study, information on other possible contributors, such as mental illness was not available. CONCLUSIONS These findings are discussed in light of international studies. Continuing studies are required to confirm the trend in increasing seasonality in Ireland. Since suicide is highest in those who are middle aged, preventive strategies should be directed to this group.