A Comprehensive Analysis of the Impact ofPseudomonas aeruginosaColonisation on Prognosis in Adult Bronchiectasis

Rationale: Eradication and suppression of Pseudomonas aeruginosa is a key priority in national guidelines for bronchiectasis and is a major focus of drug development and clinical trials. An accurate estimation of the clinical impact of P. aeruginosa in bronchiectasis is therefore essential.Methods: Data derived from 21 observational cohort studies comparing patients with P. aeruginosa colonization with those without it were pooled by random effects meta-analysis. Data were collected for key longitudinal clinical outcomes of mortality, hospital admissions, exacerbations, and lung function decline, along with cross-sectional outcomes such as quality of life.Measurements and Main Results: In the aggregate, the included studies comprised 3,683 patients. P. aeruginosa was associated with a highly significant and consistent increase in all markers of disease severity, including mortality (odds ratio [OR], 2.95; 95% confidence interval [CI], 1.98–4.40; P < 0.0001), hospital admissions (OR, 6.57; 95% CI, 3.19–13.51; P < 0.0001), and exacerbations (mean difference, 0.97/yr; 95% CI, 0.64–1.30; P < 0.0001). The patients with P. aeruginosa also had worse quality of life on the basis of their St. George's Respiratory Questionnaire results (mean difference, 18.2 points; 95% CI, 14.7–21.8; P < 0.0001). Large differences in lung function and radiological severity were also observed. The definitions of colonization were inconsistent among the studies, but the findings were robust regardless of the definition used.Conclusion: P. aeruginosa is associated with an approximately threefold increased risk of death and an increase in hospital admissions and exacerbations in adult bronchiectasis.