Abstract Introduction Mounier-Kuhn (MKS) and Williams-Cambell syndrome (WCS) are rare congenital diseases of the lower airway tract characterized by abnormal connective tissue synthesis resulting in tracheomegaly (MKS) and cystic bronchiectasis. Like WCS, subtypes of MKS can involve the distal bronchi, resulting in cystic bronchiectasis1. Due to the markedly dilated bronchi in both conditions, mucociliary clearance is impaired, resulting in chronic infection and repeated exacerbations2. Herein we describe the prevalence and clinical characteristics of both MKS and WCS in patients with bronchiectasis (pwBE). Methods We performed a cross-sectional retrospective analysis of adult pwBE enrolled in the US Bronchiectasis and Nontuberculous Mycobacteria (NTM) Research Registry (BRR). Patients diagnosed with all-cause bronchiectasis, idiopathic bronchiectasis, Mounier-Kuhn, or Williams-Campbell syndrome were included. Idiopathic bronchiectasis was defined as a diagnosis of bronchiectasis without known etiology or NTM diagnosis. Clinical characteristics were described descriptively for the overall sample and across the four mutually exclusive groups. All continuous variables were summarized using the non-missing sample size, median and interquartile range IQR. Categorical variables were similarly described using frequency and percentage. No statistical measures or inferences were computed. Results 6329 pwBE met the inclusion criteria, of which 20 (0.32%) had MKS and 7 had WCS (0.11%). The median age (inter quartile range) of patients with MKS (pwMKS) or WCS (pwWCS) was 65 (58.5 to 71.0) and 61 (53 to 71.0) years, respectively, which is lower than the median age of the overall bronchiectasis cohort (69.0). 65% of pwMKS were born male compared to the overall bronchiectasis cohort (22%), were more likely to have isolated Pseudomonas aeruginosa (50% vs. 25%), and have cavitary disease (19% vs. 9%). 71% of PwWCS were born female, similar to the overall BE cohort, and were more likely than pwMKS to have isolated NTM species on respiratory culture (60%, similar to overall BE cohort). 40% of PwMKS and 43% of pwWCS were non-white, required supplemental oxygen (26% and 14%), and had exacerbations and pulmonary-related hospitalization (81% and 60%) compared to patients with idiopathic bronchiectasis. Conclusion Combined, the diagnoses of MKS and WCS in the overall U.S. BRR cohort was low at 0.43%. Due to the rarity of these conditions, and WCS in particular, conclusions are limited. Overall, patients with MKS or WCS were younger, non-white, and with a higher disease severity than the overall bronchiectasis cohort. This abstract is funded by: Bronchiectasis & NTM Association
Swenson et al. (Fri,) studied this question.