Secular trends in the rates and seasonality of violent and nonviolent suicide occurrences in Finland during 1980-95.

BACKGROUND

Because secular trends in seasonality of different types of suicides has not been studied before, we utilized a novel statistical method to evaluate this phenomenon by using national Finnish suicide statistics during 1980-95.

METHODS

Rates were analyzed with ordinary linear regression analysis. Secular trends were evaluated using ratio-statistic and its 95% confidence intervals.

RESULTS

The rate of violent suicides increased before year 1990 and decreased since that. The nonviolent suicide rate increased continuously. The decreasing tendency of seasonality in nonviolent suicides and a slight decrease in violent suicides are seen within the three successive time periods studied.

CONCLUSIONS

Trends in rates and in seasonality of suicides might be related to changes in the health politics in Finland.

LIMITATIONS

The short time-series and lack of studying associations of suicides with socioeconomic, environmental or biological factors are limitations of our study.

CLINICAL RELEVANCE

Studying the time-dependent changes in rates and in seasonality of suicides provide a novel perspective for the evaluation of the aetiology of suicidal behaviour.