Lung function and ischemic stroke incidence : The atherosclerosis risk in communities study. Commentary

Background: Few studies have examined the relation between lung function and ischemic stroke incidence; none have studied African Americans. Methods: We followed 13,842 middle-aged adults initially free of stroke and coronary heart disease and observed 472 incident ischemic strokes over 13 years. Quartiles of FEV 1 as a percentage of predicted value (FEV 1 PP) and FVC as a percentage of a predicted value (FVCPP) were used as the indicators of lung function. Results: In the age-, race-, gender-, and education-adjusted models, both lung function measures were significantly inversely related to ischemic stroke incidence (linear trend for FEV 1 PP, p < 0.01; linear trend for FVCPP, p < 0.01), but adjustment for possible confounders attenuated these relations. For white subjects, a significant inverse relation remained even after full adjustment (relative hazards [RH] across FEV 1 PP quartiles (lowest to highest) were 1.59, 1.52, 1.26, and 1.00; and for FVCPP quartiles were 1.56, 1.80, 1.09, and 1.00 [trend for both, p < 0.05]). There was no association for African Americans (RH across FEV 1 PP and FVCPP quartiles were 0.74, 0.89, 0.73, 1.00 [linear trend, p = 0.27] and 0.81, 1.07, 0.61, 1.00 [linear trend, p = 0.75], respectively). An inverse relation between lung function and ischemic stroke was also observed among white subjects who never smoked (FEV 1 PP) or had no respiratory symptoms (both FEV 1 PP and FVCPP) but not among their African-American counterparts. Conclusions: Among white subjects, participants with impaired lung function have a modestly higher risk of ischemic stroke even if they have never smoked nor had respiratory symptoms.