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. 2021 Oct 12;16(10):e0258302.
doi: 10.1371/journal.pone.0258302. eCollection 2021.

Ambient temperature and mental health hospitalizations in Bern, Switzerland: A 45-year time-series study

Marvin Bundo  1   2   3 , Evan de Schrijver  1   2   3 , Andrea Federspiel  4 , Andrea Toreti  5 , Elena Xoplaki  6   7 , Jürg Luterbacher  8 , Oscar H Franco  1 , Thomas Müller  4   9 , Ana M Vicedo-Cabrera  1   2
Affiliations

Ambient temperature and mental health hospitalizations in Bern, Switzerland: A 45-year time-series study

Marvin Bundo et al. PLoS One. .

Abstract

Background: Psychiatric disorders constitute a major public health concern that are associated with substantial health and socioeconomic burden. Psychiatric patients may be more vulnerable to high temperatures, which under current climate change projections will most likely increase the burden of this public health concern.

Objective: This study investigated the short-term association between ambient temperature and mental health hospitalizations in Bern, Switzerland.

Methods: Daily hospitalizations for mental disorders between 1973 and 2017 were collected from the University Hospital of Psychiatry and Psychotherapy in Bern. Population-weighted daily mean ambient temperatures were derived for the catchment area of the hospital from 2.3-km gridded weather maps. Conditional quasi-Poisson regression with distributed lag linear models were applied to assess the association up to three days after the exposure. Stratified analyses were conducted by age, sex, and subdiagnosis, and by subperiods (1973-1989 and 1990-2017). Additional subanalyses were performed to assess whether larger risks were found during the warm season or were due to heatwaves.

Results: The study included a total number of 88,996 hospitalizations. Overall, the hospitalization risk increased linearly by 4.0% (95% CI 2.0%, 7.0%) for every 10°C increase in mean daily temperature. No evidence of a nonlinear association or larger risks during the warm season or heatwaves was found. Similar estimates were found across for all sex and age categories, and larger risks were found for hospitalizations related to developmental disorders (29.0%; 95% CI 9.0%, 54.0%), schizophrenia (10.0%; 95% CI 4.0%, 15.0%), and for the later rather than the earlier period (5.0%; 95% CI 2.0%, 8.0% vs. 2.0%; 95% CI -3.0%, 8.0%).

Conclusions: Our findings suggest that increasing temperatures could negatively affect mental status in psychiatric patients. Specific public health policies are urgently needed to protect this vulnerable population from the effects of climate change.

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Conflict of interest statement

The author TM is employed by Privatclinic Meiringen, Switzerland and the author AT is employed by the European Commission. This does not alter our adherence to PLOS ONE policies on sharing data and materials. The views here expressed are those of the authors and do not necessarily reflect an official position of the European Commission. The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Catchment area of the University Psychiatric Hospital, Bern, Switzerland.
Fig 2
Fig 2. Temporal evolution of the hospitalizations due to mental disorders and mean temperature across the 45-year study period (1973–2017).
Fig 3
Fig 3. Relative risks (RR, 95% confidence interval (CI)) of mental disorders hospitalizations per 10°C increase in mean daily temperature (lag 03).
Overall result, subgroup analysis by age, sex and subdiagnosis, and temporal analysis. Null hypothesis is that there is no association (RR = 1), thus one can reject the null hypothesis when 95% confidence interval does not include 1.
Fig 4
Fig 4. Relative risks (RR, 95% confidence interval) of mental disorders hospitalizations per 10 C increase in daily mean temperature during the warm season (May-September) and heatwaves.
Null hypothesis is that there is no association (RR = 1), thus one can reject the null hypothesis when 95% confidence interval does not include 1.
See this image and copyright information in PMC

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