Mucus Plugging Across Multiple Chronic Respiratory Diseases: A Systematic Review and Meta-analysis

To systematically evaluate the prevalence, clinical characteristics, and clinical outcomes of mucus plugging across chronic respiratory diseases.

Two authors searched four databases for eligible studies. Prevalence of mucus plugging was pooled and shown as percentage with a 95% confidence intervals (CI). Differences in clinical characteristics were summarized using mean differences or odds ratios, with corresponding 95% CIs. Sensitivity analyses, subgroup analyses and meta-regression were conducted for heterogeneity assessments. Associations between mucus plugging and clinical outcomes were systematically evaluated.

A total of 33 studies was included. Prevalence of mucus plugging in asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis reached 63% (95%CI 52%, 74%), 47% (95% CI 38%, 55%) and 63% (95% CI 46%, 81%) respectively. Mucus plugging was associated with higher eosinophil counts and FeNO, and lower FEV₁% and FEV₁/FVC in asthma, as well as higher smoking odds. In COPD, mucus plugging was associated with older age and lower BMI, FEV₁%, FVC% and FEV₁/FVC (all p < 0.05). Meta-regression suggested that eosinophil counts (p < 0.01), FeNO (p = 0.02) and FEV₁% (p=0.04) contributed to heterogeneity in asthma, and inhaled corticosteroid (p < 0.01) and FEV₁/FVC (p < 0.01) contributed to heterogeneity in COPD. Presence of mucus plugging was also associated with higher risk of acute exacerbation, mortality, prolonged hospital stays and increased hospitalization costs in patients with COPD.

Mucus plugging is prevalent in chronic respiratory diseases and associated with distinct clinical characteristics and outcomes. Future research may focus on mucus plugging as a treatable trait to improve prognosis of these patients.