Bronchiectasis frequently coexists with other chronic airway diseases, particularly chronic obstructive pulmonary disease (COPD) and asthma, forming clinically significant bronchiectasis–COPD overlap and bronchiectasis–asthma overlap phenotypes. However, the global proportion of COPD and asthma among patients with bronchiectasis has not been comprehensively quantified. This study aimed to estimate the pooled proportion of COPD and asthma in bronchiectasis and to explore potential sources of heterogeneity. PubMed, Embase, and Web of Science were systematically searched up to January 8, 2026. Studies reporting the proportion of COPD or asthma in adults with bronchiectasis confirmed by high-resolution computed tomography were eligible. Random-effects models were used to calculate pooled proportions. Subgroup analyses and meta-regression were performed to explore heterogeneity. Publication bias was assessed using funnel plots and Egger’s test. Fifty-two studies (81,779 patients) were included for COPD and 47 studies (71,605 patients) for asthma. The pooled proportion of COPD among bronchiectasis patients was 18% (95% CI: 14–22%; I² = 99.4%), and the pooled proportion of asthma was 16% (95% CI: 11–20%; I² = 99.3%). Subgroup analyses revealed variations by geographic region, study design, and age. Meta-regression identified female proportion as a statistically significant but weak predictor of asthma prevalence (β = 3.97, 95% CI: 0.91–7.03; P = 0.011), explaining only 10.6% of the between-study heterogeneity. No covariates significantly explained heterogeneity in COPD prevalence. Egger’s test showed no significant publication bias (COPD: P = 0.506; asthma: P = 0.153), and sensitivity analyses confirmed the stability of the findings. COPD and asthma coexist in approximately one-fifth of patients with bronchiectasis, highlighting the importance of systematic assessment for these overlap syndromes. A weak association between female sex and asthma prevalence was observed, but this factor explained only a small fraction of the heterogeneity, indicating that other unmeasured variables are more important determinants. These findings support a more integrated, phenotype-driven approach to the management of chronic airway diseases. PROSPERO registration: CRD42023400445
Wen et al. (Fri,) studied this question.