Late Breaking Abstract - How frequent are pulmonary exacerbations in primary ciliary dyskinesia?

<bold>Introduction:</bold> Pulmonary exacerbations contribute significantly to morbidity in primary ciliary dyskinesia (PCD) and are part of the core outcome set for clinical trials. For the first time in a large dataset, we studied the incidence of pulmonary exacerbations and associated factors among people with PCD. <bold>Method</bold> We used data from Living with PCD, the world’s largest participatory PCD study. Regular questionnaires assessed symptoms and healthcare usage in the past week from 05.2020–06.2022. We used the BEAT-PCD consensus definition for pulmonary exacerbations (three or more of: increased cough, change in sputum volume and/or colour, increased shortness of breath, decision to start antibiotic treatment, malaise/tiredness/fatigue or lethargy, new or increased haemoptysis, temperature >38°C). <bold>Results:</bold> 429 adults, 36 adolescents and 195 caregivers of children completed 17,539 follow-up questionnaires (median of 17 questionnaires per person, range 1-84) for 2 years resulting in 687 person-years of follow-up. 363 participants reported at least one exacerbation. We counted 1047 exacerbations, resulting in 1.5 exacerbations per year and participant. 292 of 426 swabs (69%) taken during exacerbations were positive. Pseudomonas aeruginosa (n=147) was the most common pathogen. 50% (46/92) of COVID-19 infections reported coincided with an exacerbation. During exacerbations, participants increased their usual therapies and contacted a health professional more often (p<0.001). <bold>Conclusion:</bold> Pulmonary exacerbations remain frequent in PCD—even during the COVID-19 pandemic—and successful management will improve patients’ wellbeing and quality of life. <bold>Funding</bold> SLA 2021-08_Pedersen, BEAT-PCD