Chronic bronchitis in relation to hospitalization and mortality over three decades

Abstract

Background: The study examines the predictive value of chronic bronchitis for all cause and cause-specific hospitalizations and for mortality during the last three decades.

Methods: The study population consists of altogether 47 896 men and women aged 25-74 years who participated in the National FINRISK Study between 1982 and 2007. The study protocol included a standardized questionnaire on the symptoms of chronic bronchitis, smoking habits and other risk factors and clinical measurements at the study site. Data on hospitalizations were obtained from the National Hospital Discharge Registry, and data on the underlying causes of deaths from the National Causes of Death register. The study cohorts were followed up until the end of 2011.

Results: In study subjects with symptoms of chronic bronchitis the mean annual days of hospitalization were almost two-fold higher than in study subjects without chronic bronchitis. The increase was seen in all age -groups and both in 5-year periods for each cohort and during the whole 30-year follow-up. More specifically, hospitalizations were increased for respiratory diseases and cancer. Chronic bronchitis increased hospitalizations more in smokers and ex-smokers than in never smokers. Furthermore, chronic bronchitis was associated with increased all-cause mortality (hazard ratio (HR) 1.23) and mortality from respiratory causes, cardiovascular diseases and cancer. Smokers and ex-smokers with chronic bronchitis had an increased risk to die (HRs 2.89 and 1.69, respectively) compared with never-smokers without chronic bronchitis.

Conclusion: Symptoms of chronic bronchitis can help to identify individuals who are at risk for increased hospitalizations and mortality.

Keywords: COPD; Chronic bronchitis; Hospitalization; Mortality; Smoking.