Long-term follow-up of respiratory function in facioscapulohumeral muscular dystrophy
Sjan Teeselink, Sanne C. C. Vincenten, Nicol C. Voermans, Jan T. Groothuis, Jonne Doorduin, Peter J. Wijkstra, Corinne G.C. Horlings, Baziel G.M. van Engelen, Karlien Mul
Abstract
OBJECTIVE: To evaluate the 5-year change in respiratory function in patients with facioscapulohumeral muscular dystrophy (FSHD). METHODS: Genetically confirmed patients with FSHD aged ≥ 18 years were examined twice over five years. Forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were measured using hand-held spirometry with a face mask. Several clinical outcome measures were correlated to respiratory function. RESULTS: Ninety-two patients were included (57% male, age 18-75 years). At baseline, the spirometry outcomes of 41 patients showed a restrictive ventilatory pattern (FVC < 80% and FEV1/FVC ≥ 70% of predicted) and of 48 patients at follow-up. The mean FVC decreased from baseline to follow-up from 79.0 to 76.7% predicted (p = 0.021). This decrease was driven by a subgroup of 15 patients who had a deterioration of FVC of > 10% predicted. The subgroup of 15 patients was more severely affected at baseline (p = 0.002 for FSHD clinical score and 0.007 for Ricci score). They developed more frequently spinal and thorax deformities (p < 0.001 for kyphoscoliosis and 0.012 for pectus excavatum) and had a larger decline in axial muscle function (p = 0.020). Only weak correlations were found between the change in FVC% predicted and the change in clinical scores between baseline and follow-up. INTERPRETATION: Respiratory function remained stable in most patients with FSHD, but a subgroup of patients showed a pronounced deterioration. They showed more severe muscle weakness including the leg muscles at baseline (Ricci score ≥ 6), had spinal and thorax deformities and a relatively fast decline in axial muscle function at follow-up.