Respiratory functions, respiratory muscle strength and fatigue in patients with pediatric-onset multiple sclerosis: a comparative cross-sectional study

Purpose To compare PwPOMS and healthy controls in terms of respiratory functions, respiratory muscle strength, and fatigue, and investigate the determining role of fatigue on respiratory parameters. Methods Twenty-five PwPOMS and 15 healthy controls were included in the study. Maximum inspiratory pressure (MIP) and expiratory pressures (MEP) were measured. Respiratory functions were evaluated using spirometry, and predicted values were recorded for FEV1, FVC, FEV1/FVC, and PEF. Fatigue levels were assessed using the Pediatric Quality of Life Inventory Multidimensional Fatigue Scale (PedsQL-MFS). Results The FEV1%pred (p = 0.022), PEF%pred (p = 0.003), MIP (p = 0.001), and MEP (p = 0.019), cognitive fatigue self-reported score of PedsQL-MFS (p = 0.037), sleep-rest fatigue (p = 0.034), cognitive fatigue (p = 0.010), and total score (p = 0.005) of PedsQL-MFS Proxy Report were significantly decreased in PwPOMS compared with their healthy peers. Regression analysis showed that the general fatigue of self-reported PedsQL-MFS was a determinator for FEV1%pred (beta= -0.467) and PEF% (beta= -0.553), and total score PedsQL-MFS was a determinator for FEV1/FVC %pred (beta= -0.599). Conclusion PwPOMS had decreased respiratory muscle strength, FEV1, and PEF, with preserved FEV1/FVC and higher fatigue levels than their healthy peers. In addition, self-reported fatigue had a determining role in respiratory functions but not respiratory muscle strength in PwPOMS. This trial is registered on ClinicalTrials.gov under "NCT05123924" available at: https://clinicaltrials.gov/ct2/show/NCT05123924.