Multimorbidity and emergency hospitalisations during hot weather

Zhiwei Xu; Weizhuo Yi; Aaron Bach; Shilu Tong; Kristie L Ebi; Hong Su; Jian Cheng; Shannon Rutherford

doi:10.1016/j.ebiom.2024.105148

Multimorbidity and emergency hospitalisations during hot weather

EBioMedicine. 2024 May 4:104:105148. doi: 10.1016/j.ebiom.2024.105148. Online ahead of print.

Authors

Zhiwei Xu¹, Weizhuo Yi², Aaron Bach³, Shilu Tong⁴, Kristie L Ebi⁵, Hong Su⁶, Jian Cheng⁶, Shannon Rutherford³

Affiliations

¹ School of Medicine and Dentistry, Griffith University, Gold Coast, Australia; Cities Research Institute, Griffith University, Gold Coast, Australia. Electronic address: xzw1011@gmail.com.
² School of Medicine and Dentistry, Griffith University, Gold Coast, Australia; School of Public Health, Anhui Medical University, Hefei, China.
³ School of Medicine and Dentistry, Griffith University, Gold Coast, Australia; Cities Research Institute, Griffith University, Gold Coast, Australia.
⁴ National Institute of Environmental Health, Chinese Center for Disease Control and Prevention, Beijing, China; School of Public Health and Social Work, Queensland University of Technology, Brisbane, Australia.
⁵ Center for Health and the Global Environment, University of Washington, Seattle, USA.
⁶ School of Public Health, Anhui Medical University, Hefei, China.

Abstract

Background: People with chronic diseases are a commonly listed heat-vulnerable group in heat-health action plans. While prior research identifies multiple health conditions that may increase vulnerability to ambient heat, there is minimal evidence regarding the implications of multimorbidity (two or more chronic diseases).

Methods: From the statewide hospital registry of Queensland, Australia, we identified people aged ≥15 years who had emergency hospitalisation(s) between March 2004 and April 2016 and previously had 0, 1, 2, or ≥3 of five chronic diseases: cardiovascular disease, diabetes, mental disorders, asthma/COPD, and chronic kidney disease. We conducted time-stratified case-crossover analyses to estimate the odds ratio of hospitalisations associated with ambient heat exposure in people with different numbers, types, and combinations of chronic diseases. Ambient heat exposure was defined as a 5 °C increase in daily mean temperature above the median.

Findings: There were 2,263,427 emergency hospitalisations recorded (48.7% in males and 51.3% in females). When the mean temperature increased, hospitalisation odds increased with chronic disease number, particularly in older persons (≥65 years), males, and non-indigenous people. For instance, in older persons with 0, 1, 2, or ≥3 chronic diseases, the odds ratios associated with ambient heat exposure were 1.00 (95% confidence interval: 0.96, 1.04), 1.06 (1.02, 1.09), 1.08 (1.02, 1.14), and 1.13 (1.07, 1.19), respectively. Among the chronic diseases, chronic kidney disease, and asthma/COPD, either existing alone, together, or in combination with other diseases, were associated with the highest odds of hospitalisations under ambient heat exposure.

Interpretation: While individuals with multimorbidity are considered in heat-health action plans, this study suggests the need to consider specifically examining them as a distinct and vulnerable subgroup.

Funding: Wellcome.

Keywords: Chronic disease; Heat-health action plan; Multimorbidity.