Incidence and predictors of self-reported pulmonary exacerbations in primary ciliary dyskinesia: an international prospective cohort study.

Introduction Pulmonary exacerbations contribute to disease progression in chronic lung diseases. In a large prospective cohort study, we studied the incidence and predictors of pulmonary exacerbations among persons with primary ciliary dyskinesia (PCD), which can inform follow-up care. We also assessed healthcare use, changes in management and pathogens during exacerbations. Methods Participants in the Living with PCD study reported increased respiratory symptoms in the past 7 days, indicating a pulmonary exacerbation, from June 2020 through May 2022 via online questionnaires. We derived incidence rates and studied predictors of pulmonary exacerbation incidence by fitting multivariable negative binomial regression models. Results We obtained data from 660 persons (408 adults, 57 adolescents, 195 children) who completed 17 853 follow-up questionnaires (median 17, range 1-84). The 1026 reported exacerbations indicate an incidence rate of 3.1 pulmonary exacerbations per person per year, with minor variation across age groups, but changes over time. Incidence was higher among adult females (incidence rate ratio (IRR) 2.0, 95% confidence interval (CI) 1.4-2.7) and those in whom Pseudomonas aeruginosa was isolated (children IRR 1.9, 95% CI 1.1-3.6; adults/adolescents IRR 1.4, 95% CI 1.0-1.9). Participants saw a health professional during only 185 of 1404 exacerbation weeks (13%). P. aeruginosa was the pathogen most frequently observed during exacerbations in children (18 of 118 samples, 15%) and adults/adolescents (132 of 303 samples, 44%). Conclusion Pulmonary exacerbations are frequent in PCD and heighten the disease burden. Patients for whom targeted management is particularly important include adult females and those who carry P. aeruginosa.