To study prevalence of chronic bronchitis (CB) in residential populations and its relationship with mortality in a 50-year follow-up.
In the late 1950’s-early 1960’s, 7047 men aged 40-59 years were enrolled in 10 European cohorts of the Seven Countries Study (in Finland, the Netherlands, Italy, Serbia and Greece). After baseline examination, follow-up for mortality was extended during 50 years (45 year in the Serbian cohorts). Prevalence of CB, and 50-year mortality from CB and other major causes of death were used as end-points to identify their determinants using multivariate models.
Prevalence of CB was directly associated with smoking habits and inversely associated with high socio-economic status (SES), forced expiratory volume in ¾ sec (FEV) and the ratio FEV/vital capacity (VC). Fifty-year mortality from CB was directly predicted by CB prevalence (from a minimum hazard ratio [HR] 2.35, 95% confidence limits [CI] 1.70-3.24, to a maximum HR 3.01, CI 2.18-5.20, depending on diagnostic criteria and different models) and age, and inversely by high SES, FEV and FEV/VC. The same applied in models predicting mortality from coronary heart disease (HR for prevalent CB: 1.53, CI 1.24-1.88), major cardiovascular diseases (HR 1.43, CI 1.23-1.67) and all-cause mortality (HR 1.48, CI 1.34-1.64) all adjusted for age, high SES, smoking habits and FEV.
CB is strongly associated with major cardiovascular disease and all-cause mortality while FEV and FEV/VC seem to carry at least partly an independent role from CB in predicting long-term mortality.
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