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Environ Health Perspect. 2017 Oct 27;125(10):107009. doi: 10.1289/EHP1756.

Longer-Term Impact of High and Low Temperature on Mortality: An International Study to Clarify Length of Mortality Displacement.

Author information

1
Department of Social and Environmental Health Research, London School of Hygiene and Tropical Medicine, London, UK.
2
School of Forestry and Environmental Studies, Yale University, New Haven, Connecticut, USA.
3
Institute of Advanced Studies at the University of São Paulo, São Paulo, Brazil.
4
Department of Environmental and Occupational Medicine, National Taiwan University, Taipei, Taiwan.
5
Department of Epidemiology and Preventive Medicine, School of Public Health and Preventive Medicine, Monash University, Melbourne, Australia.
6
Environmental Health Sciences Institute, Dublin Institute of Technology, Dublin, Ireland.
7
Department of Pediatric Infectious Diseases, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan.
8
Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.
9
Graduate School of Public Health, Seoul National University, Seoul, Republic of Korea.
10
School of Epidemiology, Public Health and Preventive Medicine, University of Ottawa , Ottawa, Canada.
11
Department of Epidemiology, Lazio Regional Health Service, Rome, Italy.
12
Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA.
13
Institute of Environmental Assessment and Water Research (IDAEA), Spanish Council for Scientific Research (CSIC) , Barcelona, Spain.
14
Shanghai Children's Medical Center, Shanghai Jiao Tong University, Shanghai, China.
15
School of Public Health, Anhui Medical University, Hefei, China.
16
School of Public Health and Social Work, Queensland University of Technology, Brisbane, Australia.
17
Department of Public Health, National Taiwan University, Taipei, Taiwan.
18
Institute of Environment, Health and Societies, Brunel University London, London, UK.

Abstract

BACKGROUND:

In many places, daily mortality has been shown to increase after days with particularly high or low temperatures, but such daily time-series studies cannot identify whether such increases reflect substantial life shortening or short-term displacement of deaths (harvesting).

OBJECTIVES:

To clarify this issue, we estimated the association between annual mortality and annual summaries of heat and cold in 278 locations from 12 countries.

METHODS:

Indices of annual heat and cold were used as predictors in regressions of annual mortality in each location, allowing for trends over time and clustering of annual count anomalies by country and pooling estimates using meta-regression. We used two indices of annual heat and cold based on preliminary standard daily analyses: a) mean annual degrees above/below minimum mortality temperature (MMT), and b) estimated fractions of deaths attributed to heat and cold. The first index was simpler and matched previous related research; the second was added because it allowed the interpretation that coefficients equal to 0 and 1 are consistent with none (0) or all (1) of the deaths attributable in daily analyses being displaced by at least 1 y.

RESULTS:

On average, regression coefficients of annual mortality on heat and cold mean degrees were 1.7% [95% confidence interval (CI): 0.3, 3.1] and 1.1% (95% CI: 0.6, 1.6) per degree, respectively, and daily attributable fractions were 0.8 (95% CI: 0.2, 1.3) and 1.1 (95% CI: 0.9, 1.4). The proximity of the latter coefficients to 1.0 provides evidence that most deaths found attributable to heat and cold in daily analyses were brought forward by at least 1 y. Estimates were broadly robust to alternative model assumptions.

CONCLUSIONS:

These results provide strong evidence that most deaths associated in daily analyses with heat and cold are displaced by at least 1 y. https://doi.org/10.1289/EHP1756.

PMID:
29084393
PMCID:
PMC5933302
DOI:
10.1289/EHP1756
[Indexed for MEDLINE]
Free PMC Article

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