Association of daily changes in air temperature and other meteorological variables on suicide frequency in Bavaria
Final Report Abstract
Researchers worldwide have reported a seasonal pattern of suicides with peaks in spring and early summer. However, there are only a few studies investigating the association of daily changes of meteorological variables and suicides. Daily data of suicides and meteorological variables were available for four Bavarian cities and ten counties. Immediate, delayed and cumulative effects of air temperature, sunshine duration, cloud cover, relative humidity as well as precipitation on suicides were analyzed using a time-stratified case-crossover approach. Potential effect modifiers were specific weather conditions, personal or regional characteristics, and season. An increase in air temperature by 5°C was associated with a 4.1% (95%-confidence interval: 0.97; 7.4%) and 5.1% (2.0; 8.4%) higher suicide risk on the same day and with a delay of one day, respectively. We found a similar association for the 5-day average of air temperature (4.5% (0.6; 8.5%)). On days with cloud cover between 0-6 oktas, the suicide risk was 6.2% (0.6; 12.2%) higher compared to days with high cloud cover (7-8 oktas). Temperature effects with a lag of one day were more pronounced in individuals older than 65 years (9.9% (4.3;15.8%)). While temperature was not associated with suicides in spring we found positive associations in summer, autumn, and winter. The effects of cloud cover were strongest in summer and autumn. The other meteorological variables were not significantly associated with suicide. In summary, we found a higher risk for suicides in association with short-term increases in air temperature and on days with low to medium cloud cover. Whether or not meteorological conditions have a direct effect on suicidal behavior they do highlight time periods when people are more likely to commit suicide. Gaining knowledge about triggers or predictive factors of these tragic events is important to help clinicians and therapists to advise potential victims as well as friends and relatives in order to improve suicide prevention.
