Association between environmental factors and emergency hospital admissions due to Alzheimer's disease in Madrid.
BACKGROUND
There are scarce studies of time series that analysed the short-term association between emergency hospital admissions due to Alzheimer's disease (AD) and environmental factors. The objective is to analyse the effect of heat waves, noise and air pollutants on urgent hospital admissions due to AD in Madrid.


METHODS
Longitudinal ecological time series study was performed. The dependent variable was the emergency AD hospital admissions occurred in Madrid during the period 2001-2009. Independent variables were: Daily mean concentrations (μg/m3) of air pollutants (PM2.5and PM10; O3 and NO2); maximum daily temperature (°C) and daily and night noise levels (dB(A)). Relative Risk (RR) for an increment in interquartile range, and Attributable Risk (AR) values were calculated through GLM with Poisson link.


RESULTS
Our findings indicated that only PM2.5concentrations at lag 2 with a RR: 1.38 (95% CI: 1.15-1.65); AR 27.5% (95% CI: 13.0-39.4); and heat wave days at lag 3 with a RR: 1.30 (95% CI: 1.12-1.52); AR 23.1% (95% CI: 10.7-34.2) were associated with AD hospital admissions.


CONCLUSIONS
A reduction in AD patients' exposure levels to PM2.5and special care of such patients during heat wave periods could result in a decrease in both emergency AD admissions and the related health care costs.
Autonomous University of Madrid - Ciudad Universitaria de Cantoblanco, 28049 Madrid, Spain; CIBER en Epidemiología y Salud Pública (CIBERESP), Madrid, Spain; Evaluation and Intervention Methods Service from Barcelona Public Health Agency, Spain. Electronic address: ext_dculqui@aspb.cat.
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Culqui
Department of Epidemiology and Biostatistics, National School of Public Health, Carlos III Institute of Health, Avda. Monforte de Lemos 5, 28029 Madrid, Spain.
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Linares
Department of Epidemiology and Biostatistics, National School of Public Health, Carlos III Institute of Health, Avda. Monforte de Lemos 5, 28029 Madrid, Spain.
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Ortiz
Department of Epidemiology and Biostatistics, National School of Public Health, Carlos III Institute of Health, Avda. Monforte de Lemos 5, 28029 Madrid, Spain.
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Carmona
Department of Epidemiology and Biostatistics, National School of Public Health, Carlos III Institute of Health, Avda. Monforte de Lemos 5, 28029 Madrid, Spain.
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Díaz
D000397:Air Pollution / Q000032:analysis*; D000544:Alzheimer Disease / Q000453:epidemiology*; D002947:Cities; D006760:Hospitalization / Q000639:trends*; D006358:Hot Temperature; D006801:Humans; D009622:Noise; D052638:Particulate Matter; D018570:Risk Assessment; D013030:Spain
D052638:Particulate Matter
Air pollution; Alzheimer's disease; Heat waves; Hospital admissions; PM(2.5)