A comprehensive analysis of the impact of <i>Pseudomonas aeruginosa</i> colonization 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 &lt; 0.0001), hospital admissions (OR, 6.57; 95% CI, 3.19-13.51; P &lt; 0.0001), and exacerbations (mean difference, 0.97/yr; 95% CI, 0.64-1.30; P &lt; 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 &lt; 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.