LONGITUDINAL COURSE OF LUNG FUNCTION IN MYOTONIC DYSTROPHY TYPE 1

Introduction: Quality of life and prognosis among patients with myotonic dystrophy type 1 (DM1) depend on the degree of respiratory impairment. However, the changes over time in pulmonary function in DM1 have not been clearly described. Methods: We retrospectively reviewed pulmonary function tests of 80 DM1 patients followed for at least 5 years. Results: During 9.02 +/- 3.4 years of follow-up, the average annual changes were: forced vital capacity (FVC) -0.034 +/- 0.06 L (-0.72 +/- 1.7% predicted); forced expiratory volume in 1 second (FEV1) -0.043 +/- 0.05 L (-1.07 +/- 1.7% predicted); and total lung capacity (TLC) -0.047 +/- 0.1 L (-1.15 +/- 1.7% predicted). Conclusions: These results suggest that, compared with other neuromuscular disorders, DM1 is, overall, associated with slowly progressive impairment of lung function.