The Impact of Age of Diagnosis in Children with Primary Ciliary Dyskinesia

<b>Rationale:</b> The typical symptoms of primary ciliary dyskinesia (PCD) manifest after birth and in early infancy, but diagnosis is often not confirmed during infancy. There is currently a lack of evidence in PCD regarding the impact of the age of the patient at the time of diagnosis on clinical outcomes. <b>Objective:</b> To determine whether early diagnosis of PCD is related to improved long-term outcomes. <b>Methods:</b> This was a retrospective study of patients diagnosed with PCD between 2000 and 2022. We divided our cohort into three groups according to the age at diagnosis: (1) early diagnosis (age <1 year), typical diagnosis (age 1-7 years), and late diagnosis (age 8-14 years). We compared various clinical long-term outcomes between the groups. <b>Results:</b> During the study period, 110 patients were included in the analysis, with 41 patients in the early diagnosis group, 35 in the typical diagnosis group, and 34 in the late diagnosis group. Unexplained neonatal respiratory distress and organ laterality defect were more common in the early diagnosis group, with respective rates in the early, typical, and late diagnosis groups of 80%, 53%, and 61% for neonatal respiratory distress (<i>P</i> = 0.045) and 64%, 50%, and 18% for laterality defect (<i>P</i> < 0.001). At the end of the first decade of life, patients in the early and typical-age diagnosis groups had better forced expiratory volume in 1 second compared with the late diagnosis group (93.5% and 93.1% vs. 80.2%; <i>P</i> = 0.002), but there was no significant change in the annual rate of decline between the groups when diagnosis had been confirmed. Patients diagnosed late had significantly higher rates of pulmonary exacerbations than those diagnosed at a typical age (1.95 vs. 0.75 per year; <i>P</i> < 0.01) <b>Conclusions:</b> Late diagnosis (age ≥8 years) was associated with lower forced expiratory volume in 1 second throughout childhood, although, once diagnosed, the annual rate of decline was not different. These findings demonstrate the negative effect of delayed diagnosis in pediatric PCD.