Lung Function Recovery from Pulmonary Exacerbations Treated with Oral Antibiotics in Primary Ciliary Dyskinesia

<b>Rationale:</b> Patients with primary ciliary dyskinesia (PCD) experience acute pulmonary exacerbations (PExs). In patients with cystic fibrosis (CF), PExs that were treated with oral antibiotics (oPExs) were found to be related to short- and long-term lung function deficits; however, the impact of oPExs on lung function in patients with PCD has not yet been assessed. <b>Objectives:</b> We sought to assess the impact of oPExs on lung function recovery in PCD and determine the factors associated with poorer response. <b>Methods:</b> This was a retrospective study of pediatric patients with PCD who were followed from 2000 to 2022 at The Hospital for Sick Children (Toronto, Ontario, Canada). PExs were defined as an increase in baseline symptoms with a physician's decision to treat with systemic intravenous or oral antibiotics. Lung function recovery was defined as a forced expiratory volume in 1 second (FEV₁) measurement ⩾90% of a stable baseline within 12 months before the PEx. Univariate and multivariate analyses were completed to identify risk factors for nonresponse. <b>Results:</b> A total of 337 PEx events in 85 patients were included in this analysis, of which 297 (88%) were treated with oral antibiotics. The mean follow up time for patients was 6.7 years (SD = 3.5), and the mean age of patients with an oPEx was 12.5 years (SD = 3.2). Patients with an oPEx had a significant drop from baseline in mean FEV₁ values at the time of the PEx (85.1-69.5%), with absolute and relative changes of -10.4% and -12.9%, respectively. At follow up (3 mo post PEx) and up to 12 mo post PEx, the means for FEV₁ were 79.6% and 84.1%, respectively. A total of 73.2% of the patients had lung function recovery at the follow up visit, which increased to 84.2% within 1 year postevent. We identified two risk factors for nonresponse: being a nonresponder on the last PEx and younger age at time of the oPEx. <b>Conclusions:</b> oPExs in patients with PCD show a similar pattern previously seen in patients with CF who showed a decrease in FEV₁ during exacerbation and an improvement posttherapy. Most oPEx events recover to baseline FEV₁ within the year postexacerbation, with younger age and being a nonresponder in the last PEx identified as risk factors for nonresponse.