Reduction in the suicide rate during Advent--a time series analysis.

Research has shown that there are different seasonal effects in suicide. The aim of this study is to demonstrate that the decrease in suicide rate at the end of the year is extended over the last weeks of the year and represents a specific type of seasonal effect. Suicide data were extracted from individual records of the Swiss mortality statistics, 1969-2003. The data were aggregated to daily frequencies of suicide across the year. Specifically, the period October-February was examined using time-series analysis, i.e., the Box-Jenkins approach with intervention models. The time series models require a step function to account for the gradual drop in suicide frequencies in December. The decrease in suicide frequencies includes the whole Advent and is accentuated at Christmas. After the New Year, there is a sharp recovery in men's suicide rate but not in women's. The reduction in the suicide rate during the last weeks of the year exceeds the well-recognised effect of reduced rates on major public holidays. It involves valuable challenges for suicide prevention such as timing of campaigns and enhancement of social networks.