Seasonality in Violent and Nonviolent Methods of Suicide Attempts: A Cross-Sectional Study on Systematic Registry Data

Little attention has been paid to seasonality in suicide in Iran. Time pattern in suicide deaths and suicide attempts for some related factors such as gender, mental disorders has been found. In present study, we focus on suicide methods and the association with seasonality and other putative covariates such as gender. Through a cross-sectional study, overall identified suicide attempts and suicide deaths in the province of Ilam from 1 January 2010 and 31 December 2014 were enrolled. We used Edwards test for test of seasonality in suicide methods. Seasonal effect (peak/trough seasons) and (deaths/attempts suicide) was explored by ratio statistics, the null hypothesis being that the attempted suicides in each method group are evenly distributed over a year. More suicide attempts by hanging 29.4% and self-immolation 41.4% were observed in spring and differ by season pattern in both genders. The overall distribution of suicides by violent and non-violent methods was (males x2=6.3, P=0.041, females x2=7.7, P=0.021) and (males x2=44.5, P=0.001, females x2=104.7, P=0.001), respectively. The peak and trough seasons was observed in taking medications and self-poisoning for spring and winter. Suicide with alcohol was no differ by season pattern (x2=1.0, P=0.460). Suicide in Ilam illustrates a significant seasonality for both violent and non-violent methods of suicide, in both genders, the two peaks were observed in spring and autumn for violent suicides, and spring and summer in non-violent suicides.