Ambient temperature and mental health hospital admissions in Cyprus during 2000-2019

The global burden of mental health diseases is on the rise. Emerging evidence suggests that temperature may play a role in exacerbating mental health outcomes. However, little is known about the impact of ambient temperatures on mental health in one of the world’s fast-warming regions: in the Eastern Mediterranean region. The aim of the study is to examine the association between ambient temperature and mental health hospital admissions in Cyprus between 2000 and 2019. We conducted a case-crossover study using national mental and behavioral disorders hospital admissions data, as diagnosed by physicians using the International Classification of Diseases, Tenth Revision (ICD-10) codes F00-F99. We matched daily hospitalization to the corresponding daily temperature and relative humidity, using data aggregated across all five districts of Cyprus. Data were analyzed in a conditional Quasi-Poisson model, including 1- 3- 5- and 7-day moving average lags. Analysis was also stratified by type of mental disorder, sex and age groups. We analyzed 9,119 mental health hospital admissions, of which 3,881 (42.6%) were schizophrenia disorders. Cases were almost evenly distributed by sex, and 58% occurred among individuals 17-50 years old. For every 5 °C-increase in a 7-day moving average, mental health hospital admissions from any cause increased by 18% (95% CI: 8-29%). Similarly, admissions for schizophrenia disorders increased by 23% (95% CI: 8-40%). We found no association between temperature and mood (affective) disorders. Sex stratification showed that the risk was significant among males, (% Change: 25%; 95% CI: 8-45%) and males with schizophrenia (% Change: 28%; 95% CI: 7-52%). By age, people aged 17-50 years had the highest effect estimates (% Change: 27%; 95% CI: 11-44%; and schizophrenia % Change: 32%; 95% CI: 13-55%). Our results suggest an association between exposure to high ambient temperature and increased risk of mental disorders hospital admissions in Cyprus. Mental health ought to be included as a core outcome in relevant heat-related policies.