A National analysis of the short term effect of PM2.5 on hospitalizations and mortality in subjects with diabetes and the neurological impairment
Background: Short-term exposure to ambient air pollution is associated with mortality and morbidity; diabetes, Parkinson's disease, dementia, and Alzheimer's disease are also a growing burden.
Aims: to estimate the short-term effects of PM2.5 on 1) hospitalizations for neurological disorders and diabetes, and 2) on mortality in all Medicare deaths and whether the mortality risks associated with PM2.5 among the elderly is modified by neurological disorders or diabetes.
Methods: We examined hospitalizations and deaths among all Medicare enrollees from 1999-2010 in 121 US cities. We conducted city-specific case-crossover analyses to estimate the short-term effects of PM2.5 on 1) hospitalizations in subjects for neurological disorders and diabetes; 2) all-cause mortality risks for all Medicare deaths, and effect modification by previous admissions for diabetes and neurological diseases. Results: 1) In the analysis of hospitalizations we found significant effects of PM2.5 on hospitalization rates for diabetes with a 0.53% increase (95% CI: 0.35-0.71) per 10 mg/m3 increase in the 2 days average of PM2.5, for Alzheimer's disease (0.42% increase, 95% CI: 0.11-0.72), for Parkinson's disease (0.79%, 0.34-1.25), and for dementia (0.59%, 0.14-1.04). 2) We found a 0.64% increase (95% CI: 0.42-0.85) in mortality rate for each 10 µg/m3 increase in the 2 days average of PM2.5 among all Medicare deaths. We found increased mortality risk in subjects with previous admissions for diabetes (0.76%, 0.39-1.12), Parkinson's disease (1.15%, 0.09-2.23), dementia (0.94%, 0.01-1.89), Alzheimer's disease (1.04%, 0.36-1.72), and multiple sclerosis (4.01%, -0.03-8.21), but these were not significantly higher than the overall mortality risk.
Conclusions: In this multi-city study we found that particles increased the risk of mortality and of hospitalizations in subjects with diabetes and neurological disorders.