Respiratory Function and Risk of Stroke

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Abstract
This report examines the relationship between lung function and risk of major stroke events (fatal and nonfatal). We completed a prospective study of 7735 men aged 40 to 59 years at screening selected at random from one general practice in each of 24 British towns. During the mean follow-up period of 14.8 years, there were 277 major stroke events in the 7650 men with data on forced expiratory volume in 1 second (FEV1). After exclusion of 499 men with definite myocardial infarction, stroke, or atrial fibrillation at screening, 7151 men experienced 239 major stroke events. Lower levels of FEV1 were associated with a significant increase in risk of stroke even after adjustment for age, smoking, social class, physical activity, alcohol intake, systolic blood pressure, antihypertensive treatment, diabetes, and preexisting ischemic heart disease. Relative risk in the low third (< 3.10 L) versus high third (> 3.65 L) was 1.4 (95% confidence interval, 1.0 to 2.0). The inverse association between FEV1 and stroke was only apparent in older men, current nonsmokers, hypertensive men, and men with preexisting ischemic heart disease. Lower FEV1 was associated with higher rates of stroke in hypertensive men irrespective of smoking status. Inclusion of FEV1 in a risk score for stroke provided only a small increase in the absolute risk or the yield of cases in the top fifth of the score distribution during the follow-up period. Lower levels of FEV1 are associated with an increased risk of stroke in those already at high risk, eg, those with ischemic heart disease or hypertension. However, the association is not strong enough to warrant the use of FEV1 in making clinical decisions regarding the treatment of hypertension as it relates to the prevention of stroke.