Chronic bronchitis in young adults linked with recurrent respiratory infections

Chronic bronchitis in young adults is associated with recurrent respiratory infections and early-life exposures, according to findings published in the European Respiratory Journal.

“Recurrent respiratory infections may be as common in young adult patients with chronic bronchitis as in elderly patients,” Gang Wang, MD, researcher in the department of integrated traditional Chinese and Western medicine at West China Hospital, Sichuan University, China, and the Institute of Environmental Medicine and the department of clinical science and education at the Karolinska Institute, Stockholm, and colleagues wrote. “We identified current and former smoking as well as early-life air pollution exposures and childhood asthma as potential risk factors, and exclusive breastfeeding as a protective factor for chronic bronchitis, which underline the importance of early-life events for maintaining lung health during the life course.”

Researchers analyzed questionnaire data and clinical measures from 3,064 participants from the 24-year follow-up of the Swedish population-based birth BAMSE cohort. Chronic bronchitis was assessed as the combination of cough and mucus production in the morning during winter.

From birth and onward, environmental and clinical data were used to identify risk factors associated with the development of chronic bronchitis. At the 24-year follow-up, 2,890 respondents provided information on morning cough and mucus production and 2,030 respondents performed lung function measurements using spirometry.

The overall prevalence of cough only was 3.3% (95% CI, 2.6-3.9) and the prevalence of mucus only was 9.6% (95% CI, 8.5-10.6). The prevalence of overall chronic bronchitis was 5.5% (95% CI, 4.6-6.3), with no difference in prevalence between males and females.

More than three self-reported respiratory infections in the past year were reported in 49% of chronic bronchitis cases compared with 18% of participants without chronic bronchitis (P < .001). Among those with chronic bronchitis, 37% were current smokers compared with 19% of participants without chronic bronchitis.

Post-bronchodilator FEV₁/FVC was significantly lower among those with chronic bronchitis compared with those without chronic bronchitis (–0.06 vs. 0.13; P = .027).

Researchers observed daily smoking (adjusted OR = 3.85; P < .001), air pollution exposure to black carbon at age 1 to 4 years (aOR = 1.71; P = .009) and exclusive breastfeeding for 4 or more months (aOR = 0.66; P = .044) were independent risk factors for chronic bronchitis in this cohort.

These results were robust even after adjusting for several potential confounders, according to the researchers.