Respiratory function and evaluation in individuals with facioscapulohumeral muscular dystrophy in the Muscular Dystrophy Surveillance, Tracking and Research Network

Using data from the US population-based, multisite Muscular Dystrophy Surveillance, Tracking, and Research Network (MD STARnet), we describe respiratory testing and insufficiency among people with facioscapulohumeral muscular dystrophy (FSHD) diagnosed during 2008-2016. We calculated frequencies and proportions for selected outpatient respiratory assessments (pulmonary function tests [PFTs], forced vital capacity (FVC), inspiratory/expiratory pressure, and polysomnograms) and abnormal test results. We examined frequencies by disease characteristics (FSHD type, ages of onset, non-ambulatory status, scoliosis, lordosis), obesity, and number of health encounters. Of 170 people with FSHD, 20.0% underwent PFTs during 2008-2016. Polysomnograms were infrequent (14.1%). FVC <80% predicted was recorded for 64.7% of people tested; additional respiratory outcomes were rare (<5%). Frequency of evaluations and respiratory insufficiency were higher among those with known risk factors and longer follow-up. We observed low proportions of respiratory testing among all confirmed cases of FSHD, but relatively high proportions of mild respiratory insufficiency among those tested. The higher proportions of testing among people with conditions that increase risk of respiratory complications suggest targeted monitoring. Broad implementation of the FSHD guidelines recommending all individuals receive baseline respiratory evaluation at diagnosis could identify respiratory insufficiency as a complication of FSHD.