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 seven 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 IRR 1.4, 95% CI 1.0-1.9). Participants saw a health professional during only 185 of 1404 exacerbation weeks (13%). Pseudomonas aeruginosa was the pathogen most frequently observed during exacerbations in children (18 of 118 samples, 15%) and adults (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 Pseudomonas aeruginosa.

The authors have declared no competing interest.

Our research was funded by the Swiss National Science Foundation, Switzerland (SNSF 320030B_192804/1, SNSF 10001934), the Swiss Lung Association, Switzerland (2021-08_Pedersen), and we also received support from the PCD Foundation, USA; the Verein Kartagener Syndrom und Primäre Ciliäre Dyskinesie, Germany; PCD Support UK, United Kingdom; and PCD Australia, Australia. Study authors participate in the BEAT-PCD Clinical Research Collaboration supported by the European Respiratory Society.

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The cantonal ethics committee of Bern, Switzerland, approved the study (study ID: 2020-00830).

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

Living with PCD data are available upon reasonable request by contacting Claudia Kuehni (claudia.kuehni@unibe.ch).