Epidemiology and clinical characteristics of primary ciliary dyskinesia in Japan: A nationwide database analysis.

BACKGROUND

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterized by impaired mucociliary clearance causing chronic respiratory infections and progressive lung disease. Despite its clinical significance, comprehensive epidemiological data on PCD in Japan are lacking.

METHODS

Patients diagnosed with PCD between 2015 and 2023 and included in the National Database of Health Insurance Claims (NDB) were retrospectively evaluated. Prevalence and incidence rates were calculated, while patient demographics, including age, sex, regional distribution, comorbidities, and survival, were described.

RESULTS

A total of 1764 patients with PCD were identified. The prevalence rate per 1,000,000 population increased from 3.8 in 2015 to 10.2 in 2023. Between 2015 and 2023, 1384 patients were newly diagnosed with PCD, with an incidence rate per 1,000,000 population ranging from 0.8 in 2015 to 1.2 in 2023. Among newly diagnosed patients, 25%, 47%, 18%, and 11% were aged 0-19, 20-59, 60-74, and ≥75 years, respectively. The male-to-female ratio was practically equal. Regional disparities in diagnosis rates were observed. One-third of the PCD patients were diagnosed with Kartagener syndrome. Nontuberculous mycobacterial infection was identified in 114 patients (8%), while long-term oxygen therapy was required in 138 patients (10%). The 5-year overall survival rate was 88%.

CONCLUSIONS

This study has been the first to provide comprehensive epidemiological data on PCD in Japan. Prevalence rates were lower than international estimates, PCD was predominantly diagnosed during adulthood, and regional disparities were noted. Overall, our findings emphasize the importance of PCD awareness and expansion of diagnostic capabilities and healthcare systems throughout Japan.