Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis

Abstract

Background: Several studies have identified strong effects of high temperatures on mortality at population level; however, individual vulnerability factors associated with heat-related in-hospital mortality are largely unknown. The objective of the study was to evaluate heat-related in-hospital mortality using a multi-city casecrossover analysis. Methods: We studied residents of four Italian cities, aged 65+ years, who died during 1997-2004. For 94 944 individuals who died in hospital and were hospitalised two or more days before death, demographics, chronic conditions, primary diagnoses of last event and hospital wards were considered. A city-specific case-crossover analysis was performed to evaluate the association between apparent temperature and mortality. Pooled odds ratios (OR) of dying on a day with a temperature of 30uC compared to a day with a temperature of 20uC were estimated with a random-effects meta-analysis. Results: We estimated an overall OR of 1.32 (95% confidence interval: 1.25, 1.39). Age, marital status and hospital ward were important risk indicators. Patients in general medicine were at higher risk than those in high and intensive care units. A history of psychiatric disorders and cerebrovascular diseases gave a higher vulnerability. Mortality was greater among patients hospitalised for heart failure, stroke and chronic pulmonary diseases. Conclusions: In-hospital mortality is strongly associated with high temperatures. A comfortable temperature in hospitals and increased attention to vulnerable patients during heatwaves, especially in general medicine, are necessary preventive measures.After the disturbing increase in number of deaths observed in several European countries during the summer of 2003, 1 2 a considerable research effort is being conducted to evaluate the impact of the high temperature-related mortality, 3-5 the geographical differences in the impact, 6 the development of watching/warning systems 7 8 and the specific individual social and clinical factors that confer susceptibility to heat stress, especially among the elderly.9 People living alone and of low socioeconomic status seem to be particularly vulnerable.10 11 The research efforts are also intended to guide acute medical care, public health interventions and social services during heatwaves.We have recently reported the results of a multicity, population-based, case-crossover analysis conducted in four Italian cities to evaluate the overall impact of heat-related mortality and the specific subpopulations that are vulnerable to hot weather. 9 Extensive record linkage procedures were used to characterise mortality records for subjects aged 35+ with respect to previous morbidity. We found that the elderly, women, widows/widowers and subjects with psychiatric disorders, depression, heart conduction disorders and previous stroke are at higher risk of dying during extremely hot days. Unexpectedly, we found that the increase in mortality caused by high temperature was not limited to individuals residing in private ...

Assessment of the effect of cold and hot temperatures on mortality in Ontario, Canada: a population-based study

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Effects of diurnal variations in temperature on non-accidental mortality among the elderly population of Montreal, Québec, 1984–2007

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Climate change and respiratory diseases

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