Chronic bronchitis associated with increased mortality in current, former smokers

Nonobstructive chronic bronchitis was associated with increased mortality in current and former smokers, according to a review and meta-analysis published in Chest.

“In smokers with normal spirometry, chronic bronchitis is associated with exacerbations and hospitalizations,” Spyridon Fortis, MD, clinical associate professor in the division of pulmonary, critical care and occupational medicine at the University of Iowa, and colleagues wrote. “Prior epidemiological studies have examined the association of nonobstructive chronic bronchitis and all-cause mortality with conflicting results. The effect of nonobstructive chronic bronchitis on morality is unclear.”

Researchers identified eight articles that included chronic bronchitis and mortality in their title and/or abstract from the PubMed and Embase databases. Their goal was to evaluate the association between nonobstructive chronic bronchitis and all-cause mortality. Using the Newcastle-Ottawa Quality Assessment Scale, researchers assessed the quality of the studies and stratified the analysis by chronic bronchitis definition and smoking status.

Nonobstructive chronic bronchitis was associated with all-cause mortality (HR = 1.37; 95% CI, 1.26-1.5) without any significant heterogeneity (P = .14). Chronic bronchitis was also associated with increased mortality in studies that defined chronic bronchitis as the presence of any respiratory symptoms (HR = 1.28; 95% CI, 1.1-1.48) and in all other studies (HR = 1.4; 95% CI, 1.26-1.56).

In addition, nonobstructive chronic bronchitis was associated with increased mortality among current smokers (HR = 1.49; 95% CI, 1.35-1.64) but not among never smokers (HR = 1.22; 95% CI, 0.9-1.66) with moderate heterogeneity (P = .1).

“Nonobstructive chronic bronchitis in smokers may reflect a different type of chronic lung disease than COPD or may precede COPD diagnosis,” the researchers wrote. “Further research should investigate whether nonobstructive chronic bronchitis may benefit from early therapeutic intervention.”