ABSTRACT
Introduction In the past, only few patients with primary ciliary dyskinesia (PCD) were diagnosed with the test combination recommended by guidelines (nasal nitric oxide (nNO), genetic testing, and biopsy for electron or video microscopy) [Halbeisen, ERJ, 2019]. In a large international participatory study of people with PCD, we assessed the current situation. Methods We used data from COVID-PCD, an international study of people with PCD, who participated between 2020 and 2022. Participants described their diagnostic tests in an online questionnaire, and we used logistic regression to identify explanatory factors. Results 728 participated (median age 27 years, IQR: 12-43;60% female). Among them, 92% reported that any diagnostic testing had been done: 49% nNO, 59% genetics, and 75% biopsy for electron or video microscopy. Most did not know whether the biopsy sample had been analysed with transmission electron microscopy or video microscopy. Biopsy was most frequent in all countries except in North America where genetic testing predominated. Only 36% of participants reported all three tests. This proportion was highest in Germany (61%) and lowest in Australia (19%). Recently diagnosed patients reported more tests (nNO OR 1.7, 95%CI 1.1-2.6, genetics OR 4.5, 95%CI 2.9-6.9), and those with situs inversus less (nNO OR 0.5, 95%CI 0.3-0.7, biopsy OR 0.4, 95%CI 0.3-0.7, genetics OR 0.7, 95%CI 0.5-0.97). Conclusion Diagnostic testing in people with PCD differed by country and few reported having undergone all recommended tests. Patients diagnosed long ago should be recalled for supplementary testing to improve diagnostic characterisation as a prerequisite for personalised medicine.