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Nasal nitric oxide (nNO) is extremely low in most people with primary ciliary dyskinesia (PCD) and its measurement is an important contributor to making the diagnosis. Existing guidelines and technical standards focus on nNO measurements in older, cooperative children using chemiluminescence analysers. However, measurements of nNO in pre-school-age children (age 2-5 years) may facilitate early diagnosis and electrochemical rather than chemiluminescence analysers are widely used. Pre-schoolers often need different methods to be employed when measuring nNO. Hence, a European Respiratory Society Task Force has developed this technical standard as the first step towards standardising sampling, analysis and reporting of nNO measured as part of the diagnostic testing for PCD in all age groups, including pre-school-age children. Furthermore, we considered both chemiluminescence and electrochemical analysers that are in use worldwide. There was a paucity of quality evidence for electrochemical analysers and sampling methods used in young children, and the Task Force proposes future research priorities to allow updates of this technical standard., Competing Interests: Conflict of interest: N. Beydon reports educational writing payments as a member of the HERMES examination committee for paediatric respiratory medicine of the European Respiratory Society, and a leadership role as Chair of Group 07.01 of the European Respiratory Society (Paediatric respiratory physiology and sleep), outside the submitted work. P. Latzin reports grants from Vertex and OM Pharma, lecture honoraria from Vertex, Vifor and OM Pharma, and advisory board participation from Polyphor, Santhera (DMC), Vertex, Vifor, OM Pharma and Sanofi Aventis, outside the submitted work. S.D. Davis reports grants from the National Institutes of Health/National Heart, Lung, and Blood Institute, to support the present manuscript, and consulting fees from Parion Sciences and ReCode Therapeutics, and advisory board participation for the PCD Foundation, outside the submitted work. T. Ferkol reports grants from the National Institutes of Health (HL096458) to support the present manuscript, and grants from the National Institutes of Health (HL116211, HL125241, AI146999), National Health and Medical Research Council (NHMRC1043768) and Parion Sciences, advisory board participation for the PCD Foundation, Parion Sciences and Translate Bio, and is past president and executive board member of the American Thoracic Society, outside the submitted work. J.S. Lucas reports grants from AAIR Charity and NIHR Research for patient benefit, and consulting fees from Translate Bio, outside the submitted work. All other authors have nothing to disclose., (Copyright ©The authors 2023. For reproduction rights and permissions contact permissions@ersnet.org.)

The diagnostic work-up for primary ciliary dyskinesia (PCD) traditionally includes ciliary ultrastructural assessment using transmission electron microscopy (TEM). However, the identification of genetic variants of PCD that are missed by TEM, along with the development of novel diagnostic modalities for PCD that allow structural evaluation of cilia, such as immunofluorescence analysis and the increased availability of genetic testing, calls into questioning the contemporary role of TEM in the diagnostic work-up for PCD. In this manuscript, we describe the evidence for and against the use of TEM in PCD diagnosis, in light of recent developments of PCD.

Diagnostic testing for primary ciliary dyskinesia (PCD) usually includes transmission electron microscopy (TEM), nasal nitric oxide, high-speed video microscopy, and genetics. Diagnostic performance of each test should be assessed toward the development of PCD diagnostic algorithms. We systematically reviewed the literature and quantified PCD prevalence among referrals and TEM detection rate in confirmed PCD patients. Major electronic databases were searched until December 2015 using appropriate terms. Included studies described cohorts of consecutive PCD referrals in which PCD was confirmed by at least TEM and one additional test, in order to compare the index test performance with other test(s). Meta-analyses of pooled PCD prevalence and TEM detection rate across studies were performed. PCD prevalence among referrals was 32% (95% CI: 25-39%, I 2 = 92%). TEM detection rate among PCD patients was 83% (95% CI: 75-90%, I 2 = 90%). Exclusion of studies reporting isolated inner dynein arm defects as PCD, reduced TEM detection rate and explained an important fraction of observed heterogeneity (74%, 95% CI: 66-83%, I 2 = 66%). Approximately, one third of referrals, are diagnosed with PCD. Among PCD patients, a significant percentage, at least as high as 26%, is missed by TEM, a limitation that should be accounted toward the development of an efficacious PCD diagnostic algorithm.

Background: To date, diagnosis of Primary Ciliary Dyskinesia (PCD) remains difficult and challenging. We systematically evaluated the diagnostic performance of nasal Nitric Oxide (nNO) measurement for the detection of PCD, using either velum-closure (VC) or non-velum-closure (non-VC) techniques., Methods: All major electronic databases were searched from inception until March 2015 using appropriate terms. The sensitivity and specificity of nNO measurement was calculated in PCD patients diagnosed by transmission electron microscopy, high speed video-microscopy or genetic testing. Summary receiver operating characteristic (HSROC) curves were drawn using the parameters of the fitted models., Results: Twelve studies provided data for 13 different populations, including nine case-control (n = 793) and four prospective cohorts (n = 392). The overall sensitivity of nNO measured by VC techniques was 0.95 (95 % CI 0.91-0.97), while specificity was 0.94 (95 % CI 0.88-0.97). The positive likelihood ratio (LR+) of the test was 15.8 (95 % CI 8.1-30.6), whereas the negative likelihood ratio (LR-) was 0.06 (95 % CI 0.04-0.09). For non-VC techniques, the overall sensitivity of nNO measurement was 0.93 (95 % CI 0.89-0.96) whereas specificity was 0.95 (95 % CI 0.82-0.99). The LR+ of the test was 18.5 (95 % CI 4.6-73.8) whereas the LR- was 0.07 (95 % CI 0.04-0.12)., Conclusions: Diagnostic accuracy of nNO measurement both with VC and non-VC maneuvers is high and can be effectively employed in the clinical setting to detect PCD even in young children, thus potentiating early diagnosis. Measurement of nNO merits to be part of a revised diagnostic algorithm with the most efficacious combination of tests to achieve PCD diagnosis.

Background: Despite the manifestations of primary ciliary dyskinesia (PCD) in early life, the diagnosis is often much delayed. Since 1998 in Cyprus, we have established the only national diagnostic and clinical referral center for PCD., Objective: To review the phenotypic features at presentation of PCD patients in Cyprus in relation to age at diagnosis, with emphasis on previously lobectomised patients., Methods: The medical records of the diagnosed PCD patients were retrospectively reviewed to obtain clinical data on presentation., Results: Thirty patients, aged 13.9 years (range 0.1, 58.4 years), were diagnosed with PCD. Twelve of them presented after the age of 18. The most common manifestations were chronic cough (100%), chronic rhinorrhea (96.7%), sputum production (92.9%), laterality defects (63.3%), a history of pneumonia (53.3%) and neonatal respiratory distress (50%). A history of lobectomy in the past was recorded in 16.7% (5 patients). Patients who presented in adulthood had significantly higher frequency of lobectomy (41.7% vs 0%, p-value = 0.006) and had more frequently low FEV1 (58.3% vs 0%, p-value = 0.015) than those who presented before. Serial measurements of FEV1 and FVC indicated significantly lower intercepts in lobectomised compared to the adult non-lobectomised patients both in terms of FEV1 (-4.90 vs -1.80, p-value = 0.022) and FVC (-5.43 vs -1.91, p-value = 0.029) z-score levels. Change in FEV1 and FVC across time was not statistically significant in either group., Conclusions: PCD often remains undiagnosed up to adulthood accompanied by appearance of advanced lung disease. Performance of lobectomies seems to be a poor prognostic factor for PCD in adulthood., (Copyright © 2015 Elsevier Ltd. All rights reserved.)