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Original article
Seasonal temperature variability and emergency hospital admissions for respiratory diseases: a population-based cohort study
  1. Shengzhi Sun1,2,
  2. Francine Laden2,3,
  3. Jaime E Hart2,3,
  4. Hong Qiu1,
  5. Yan Wang2,
  6. Chit Ming Wong1,
  7. Ruby Siu-yin Lee4,
  8. Linwei Tian1
  1. 1 School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, Hong Kong
  2. 2 Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
  3. 3 Channing Division of Network Medicine, Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, Massachusetts, USA
  4. 4 Elderly Health Service, Department of Health, Hong Kong Special Administrative Region, Hong Kong
  1. Correspondence to Dr Linwei Tian, School of Public Heath, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong; linweit{at}hku.hk

Abstract

Background Climate change increases global mean temperature and changes short-term (eg, diurnal) and long-term (eg, intraseasonal) temperature variability. Numerous studies have shown that mean temperature and short-term temperature variability are both associated with increased respiratory morbidity or mortality. However, data on the impact of long-term temperature variability are sparse.

Objective We aimed to assess the association of intraseasonal temperature variability with respiratory disease hospitalisations among elders.

Methods We ascertained the first occurrence of emergency hospital admissions for respiratory diseases in a prospective Chinese elderly cohort of 66 820 older people (≥65 years) with 10–13 years of follow-up. We used an ordinary kriging method based on 22 weather monitoring stations in Hong Kong to spatially interpolate daily ambient temperature for each participant’s residential address. Seasonal temperature variability was defined as the SD of daily mean summer (June–August) or winter (December–February) temperatures. We applied Cox proportional hazards regression with time-varying exposure of seasonal temperature variability to respiratory admissions.

Results During the follow-up time, we ascertained 12 689 cases of incident respiratory diseases, of which 6672 were pneumonia and 3075 were COPD. The HRs per 1°C increase in wintertime temperature variability were 1.20 (95% CI 1.08 to 1.32), 1.15 (1.01 to 1.31) and 1.41 (1.15 to 1.71) for total respiratory diseases, pneumonia and COPD, respectively. The associations were not statistically significant for summertime temperature variability.

Conclusion Wintertime temperature variability was associated with higher risk of incident respiratory diseases.

  • COPD epidemiology
  • pneumonia

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Footnotes

  • Contributors FL and LT contributed to the conception and design and interpreted the results; RSL and CMW collected the cohort data; SS and HQ conducted statistical analyses; SS, FL, JEH, YW and LT drafted the manuscript for important intellectual content. All authors critically reviewed and accepted the final version of the manuscript.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent Not required.

  • Ethics approval Ethics approval was obtained from the Ethics Committee of the Faculty of Medicine, The University of Hong Kong and of the Department of Health of Hong Kong.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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