Disease course and prognostic factors of progressive muscular atrophy

Objective To investigate the natural history and prognostic factors in patients with nonhereditary, adult-onset progressive muscular atrophy. Design Inception cohort conducted for 18 months. Settings Three university hospitals in the Netherlands (referral centers for neuromuscular diseases). Patients Thirty-seven consecutive patients newly diagnosed (onset of weakness Main Outcome Measures Disease progression was measured at 0, 3, 6, 9, 12, 15, and 18 months by the Medical Research Council sum score, number of affected limb regions, and the Amyotrophic Lateral Sclerosis Functional Rating Scale score. Multivariate linear regression analysis was used to identify predictors of poor outcome. Clinical features and classification of phenotype during follow-up were evaluated. Survival analysis was planned after data collection, performed 5 years after the end of the study. Results Significant decline of muscle strength (mean, 6.01 Medical Research Council sum score points [95% confidence interval [CI], 3.84-8.18]; P value P value P > value Conclusions This study shows that patients with progressive muscular atrophy have a relentlessly progressive disease course. Patients with a low VC at baseline and a sharp decline of VC during the first 6 months have an especially poor prognosis.