Background: Primary ciliary dyskinesia (PCD) is a rare inherited disorder that can progress to advanced lung disease requiring lung transplantation. Current assessment strategies rely primarily on pulmonary function and imaging, which may not adequately capture systemic physiologic reserve or overall fitness relevant to transplant candidacy. Body composition analysis has emerged as an important marker of functional status in chronic lung diseases, yet its role in PCD remains poorly defined. Methods: We conducted an observational cross-sectional study to characterize body composition in 16 patients with PCD due to the RSPH4A founder variant undergoing baseline evaluation for potential lung transplantation. Body composition was assessed using multi-frequency segmental bioelectrical impedance analysis (BIA) (MC-780U PLUS; Tanita Corporation, Tokyo, Japan), including measurements of body mass index (BMI), skeletal muscle mass, body fat percentage (Fat%), visceral fat rating (VFR), total body water percentage (TBW%), and extracellular-to-total body water ratio (ECW/TBW). Spirometric data, including forced expiratory volume in one second (FEV₁% predicted), were available for all participants. Descriptive statistics were generated, and relationships between body composition parameters and lung function were explored using Spearman rank correlation analysis. Results: Median BMI in the cohort was 21.35 kg/m² (IQR 19.63-28.48), while median TBW% was 51.55%. Compared with individualized target values, TBW% was consistently lower, and ECW/TBW ratios were higher, suggesting altered body fluid distribution in patients with PCD. Muscle mass and fat measures demonstrated notable inter-individual variability. Despite these physiologic alterations, no statistically significant correlations were identified between FEV₁% and body composition parameters, including Fat%, age, TBW%, BMI, ECW/TBW, and muscle mass. Spearman correlation coefficients ranged from -0.26 to 0.22, with all p-values exceeding 0.31 at a significance threshold of α = 0.05. Age-stratified analyses suggested greater variability in BMI and fat-related measures among patients ≥25 years. Conclusions: In patients with PCD due to the RSPH4A variant (n=16), body composition analysis using multi-frequency BIA demonstrated reduced TBW% and elevated ECW/TBW, suggesting altered hydration status. Heterogeneous muscle and fat distribution was also observed, suggesting variability in body composition not fully captured by BMI. No transplant-related outcomes were assessed, and therefore clinical applicability to transplant evaluation cannot be determined. Multi-frequency BIA may provide a noninvasive method to characterize body composition, but larger longitudinal studies are required to determine associations with disease progression, functional decline, and transplant outcomes in these patients.
Velazquez et al. (Sun,) studied this question.