Factors affecting in-hospital heat-related mortality: a multi-city case-crossover analysis.
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 case-crossover 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 30 degrees C compared to a day with a temperature of 20 degrees C 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.
Stafoggia
M
M
Department of Epidemiology, Rome E Health Authority, Rome, Italy.
Forastiere
F
F
Agostini
D
D
Caranci
N
N
de'Donato
F
F
Demaria
M
M
Michelozzi
P
P
Miglio
R
R
Rognoni
M
M
Russo
A
A
Perucci
C A
CA
D000368:Aged; D004812:Epidemiologic Methods; D005260:Female; D017052:Hospital Mortality; D006760:Hospitalization; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008297:Male; D013696:Temperature; D014504:Urban Health / Q000706:statistics & numerical data*