Moe Mahjoub (@mahjoublab.bsky.social)

European Respiratory Society and American Thoracic Society guidelines for the diagnosis of Primary Ciliary Dyskinesia Primary ciliary dyskinesia (PCD) is caused by pathogenetic variants in >55 genes. PCD is associated with early-onset chronic wet cough and rhinosinusitis, laterality defects, middle ear disease, and reduced fertility. The clinical presentation is heterogeneous, and diagnosis often relies on multiple tests. The American Thoracic Society (ATS) and European Respiratory Society (ERS) have previously developed separate guidelines for diagnosis. Here, ERS and ATS members systematically reviewed the literature on diagnostic tools used in practice and developed unified evidence-based guidelines for PCD diagnosis using GRADE (Grading of Recommendations, Assessment, Development and Evaluations) methodology, and a transparent process of decision-making using Evidence-to-Decision (EtD) frameworks. The Task Force panel formulated three PICO (Patients, Intervention, Comparison, Outcomes) questions and three narrative questions. The accuracies of high-speed video microscopy (HSVM), immunofluorescence (IF), and nasal nitric oxide (nNO) were compared to a reference test of transmission electron microscopy (TEM) and/or genetics. The panel gives strong recommendation for use of HSVM, IF, and nNO as adjunct tests to TEM and/or genetics for PCD diagnosis. However, no adjunct test is suitable as a standalone test to diagnose PCD and no single adjunct or reference test is suitable to exclude PCD. Pursuing a genetic diagnosis is encouraged due to the implication on management. The panel emphasizes that tests should meet a minimum standard and proposes evaluation of patients at a referral centre experienced in diagnosis. The pretest probability based on symptoms should be considered when interpreting results. https://publications.ersnet.org/content/erj/early/2025/09/18/1399300300745-2025