Geospatial patterns of hospitalization rates for stroke with comorbid hypertension in relation to environmental sources of persistent organic pollutants: results from a 12-year population-based study.

Purpose: Recent evidence indicates that exposure to persistent organic pollutants (POPs) is emerging as an important risk factor for atherosclerosis-related diseases, including stroke. Hypertension (HTN) is a major risk factor for stroke, and some studies suggest that exposure to POPs is also a risk factor for HTN. We hypothesized that POPs increase the environmental burden of stroke with comorbid HTN.
Methods: A population-based study of hospitalization rates for stroke with comorbid HTN in populations presumably exposed to POPs, based on the zip code of residence, was conducted. Data on hospitalizations for stroke with comorbid HTN were obtained from the New York Statewide Planning and Research Cooperative System for 1993-2004. Relative risks, with 95% confidence intervals (RR, 95% CI), of hospitalization were estimated by multiple Poisson regression analysis.
Results: RR of hospitalization for stroke with comorbid HTN was 13.4% higher in populations residing in zip codes containing or abutting environmental sources of POPs (RR = 1.134; 95% CI, 1.036-1.241; p = 0.006). Also, hospitalization rates were significantly higher in males than in females (RR = 1.397; 95% CI, 1.357-1.437; p < 0.001), in African Americans than in Caucasians (RR = 3.902; 95% CI, 3.617-4.208; p < 0.001), and in older age groups (p for trend < 0.001). These statistically significant findings of the effect of demographic factors are highly consistent with the current knowledge of stroke and serve as indirect quality indicators for our model.
Conclusions: Results of our study support the hypothesis that exposure to POPs increases the environmental burden of both stroke and HTN.