Chronic respiratory disease, comorbid cardiovascular disease and mortality in a representative adult US cohort.

BACKGROUND AND OBJECTIVE

We sought to determine the relationship between chronic respiratory disease, cardiovascular disease (CVD) and mortality in a nationally representative cohort of the US population aged 40 years and older.

METHODS

We analysed data from the baseline (1988-1994) and follow-up of the Third National Health and Nutrition Examination Survey (NHANES III). Subjects were classified in to one of four categories: obstructed (forced expiratory volume in 1 s/forced vital capacity <70% and forced expiratory volume in 1 s <80% predicted), restricted (forced expiratory volume in 1 s/forced vital capacity ≥70% and forced vital capacity <80% predicted), symptomatic (neither obstructed nor restricted but reporting respiratory symptoms) and normal (none of the above). Subjects were classified as having overt CVD, CVD risk factors only or neither at the baseline examination.

RESULTS

The analysis data set included 9054 subjects, of whom 1132 (12.0%, weighted percentage (WP)) were obstructed, 1319 (10.3%, WP) were restricted and 2457 were symptomatic (27.6%, WP). Overt CVD was present at baseline in 1284 subjects (10.4 %, WP), and CVD risk factors alone were present in 4900 (53.3%, WP). Three thousand five hundred seventy-one (28.4%, WP) subjects died during the up to 18-year follow-up period. When compared with 'normal' subjects, those in the obstructed group were more likely to have overt CVD (odds ratio 1.87, 95% confidence interval: 1.15-3.04, P < 0.001), with a similar risk seen in the restricted and symptomatic group.

CONCLUSIONS

In this large US population-based cohort, the presence of obstruction, restriction or respiratory symptoms alone was associated with higher adjusted risk of overt CVD.