Exploring the association between precipitation and mental health hospitalizations in Switzerland

Abstract

Background and aim: While several studies proved the relationship between temperature and mental health, limited evidence exists on the effect of other weather factors, such as precipitation. The aim of this study was to assess the impact of precipitation on mental disorders in Switzerland between 2009–2019. Methods: Daily hospitalizations between 2009–2019 were obtained from Switzerland’s Federal Office of Statistics. Daily precipitation was taken from 2km gridded maps developed by MeteoSwiss. We conducted aggregated case-crossover analysis with a conditional quasi-Poisson regression to assess the association up to 7 days after the exposure. We considered daily precipitation in millimeters (mm), and persistent extreme precipitation events (PEP90.2) when daily precipitation exceeded the 90th percentile for more than 2 days. The analysis was conducted separately in eight Swiss main cities (Basel, Bern, Geneva, Lausanne, Lugano, Luzern, St. Gallen, and Zurich) and stratified by sex, age (<65years, ≥65years), and group of diagnosis (ICD-10). Models were adjusted by daily mean temperature. Results: The total number of hospital admissions included in the study was 147,768. On average, the risk of hospitalization increased by 38% (95%CI:1.30-1.46) for every 10mm increase in daily precipitation and by 52% (95%CI:1.33-1.74) for PEP90.2 events. Larger risks were found in males (1.67;95%CI:1.42-1.96, vs 1.38; 95%CI:1.17-1.63 in females) and under 65 years old (1.53;95CI:1.33-1.77 vs 1.45;95%CI:1.17-1.80 in ≥65years) for PEP90.2 events. By sub-diagnosis categories, larger risks were found for adult personality disorders (F60-F69) in daily precipitation (1.61;95%CI:1.42-1.83) and PEP90.2 (1.94;95%CI:1.34-2.80), while no evidence was found for developmental disorders (F80-F98) and similar risks to the average in the remaining groups. We observed a positive association in all cities with higher risks in Luzern for daily precipitation (1.68; 95%CI:1.43-1.97) and PEP90.2 (2.22; 95%CI:1.33-3.69). Conclusions: Our findings suggest that extreme precipitation events could have adverse impacts on mental health in Switzerland. Keywords: Precipitation; Climate change; Mental health