The impact of cold spells on schizophrenia admissions and the synergistic effect with the air quality index

Yangyang He; Xulai Zhang; Jiaojiao Gao; Hua Gao; Jian Cheng; Zhiwei Xu; Rubing Pan; Weizhuo Yi; Jian Song; Xiangguo Liu; Chao Tang; Shasha Song; Hong Su

doi:10.1016/j.envres.2022.113243

The impact of cold spells on schizophrenia admissions and the synergistic effect with the air quality index

Environ Res. 2022 Sep;212(Pt B):113243. doi: 10.1016/j.envres.2022.113243. Epub 2022 Apr 7.

Authors

Yangyang He¹, Xulai Zhang², Jiaojiao Gao³, Hua Gao², Jian Cheng¹, Zhiwei Xu⁴, Rubing Pan¹, Weizhuo Yi¹, Jian Song¹, Xiangguo Liu¹, Chao Tang¹, Shasha Song¹, Hong Su⁵

Affiliations

¹ Department of Epidemiology and Health Statistics, School of Public Health, Anhui Medical University, Hefei, Anhui, 230032, China; Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, China.
² Anhui Mental Health Center, Hefei, Anhui, China.
³ Pudong New Area Center for Disease Control and Prevention, Shanghai, China.
⁴ School of Public Health, Faculty of Medicine, University of Queensland, Brisbane, Australia.
⁵ Department of Epidemiology and Health Statistics, School of Public Health, Anhui Medical University, Hefei, Anhui, 230032, China; Inflammation and Immune Mediated Diseases Laboratory of Anhui Province, China. Electronic address: suhong5151@sina.com.

PMID: 35398316
DOI: 10.1016/j.envres.2022.113243

Abstract

Objectives: Under current global climate conditions, there are insufficient studies on the health influences of cold spells, especially on mental health. This study aimed to examine the effect of cold spells on schizophrenia admissions and to analyze the potential interaction effect with the air quality index (AQI).

Methods: Daily data on schizophrenia admissions and climatic variables in Hefei were collected from 2013 to 2019. Based on 20 definitions, the impacts of cold spells were quantified separately to find the most appropriate definition for the region, and meta-regression was used to explore the different effect sizes of the different days in a cold spell event. In addition, the potential interaction effect was tested by introducing a categorical variable, CSH, reflecting the cold spell and AQI level.

Results: The cold spell defined by temperature below the 6th centile while lasting for at least three days produced the optimum model fit performance. In general, the risk of schizophrenia admissions increased on cold spell days. The largest single-day effect occurred on the 12th day with RR = 1.081 (95% CI: 1.044, 1.118). In a single cold spell event, the effect of the 3rd and subsequent days of a cold spell (RR = 1.082, 95% CI: 1.036, 1.130) was higher than that on the 2nd day (RR = 1.054, 95% CI: 1.024, 1.085). Similarly, the effect of the 2nd day was also higher than that of the 1st day (RR = 1.027, 95% CI: 1.012, 1.042). We found a synergistic effect between cold spells and high AQI in the male group, and the relative excess risk due to interaction (RERI) was 0.018 (95% CI: 0.005-0.030).

Conclusions: This study suggested that the impacts of cold spells should be considered based on the definition of the most appropriate for the region when formulating targeted measures of schizophrenia. The discovery of the synergistic effect was referred to help the selection of the timing of precautions for susceptible people.

Keywords: Air quality index; Cold spell; Schizophrenia; Synergistic effect.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Air Pollution*
Cold Temperature
Hospitalization
Humans
Male
Schizophrenia* / epidemiology
Temperature