Longitudinal Assessment of Strength, Functional Capacity, Oropharyngeal Function, and Quality of Life in Oculopharyngeal Muscular Dystrophy.

ObjectiveOculopharyngeal muscular dystrophy (OPMD) is a late-onset, progressive muscle disease. Disease progression is known to be slow, but details on the natural history remain unknown. We aimed to examine the natural history of OPMD in a large nationwide cohort to determine clinical outcome measures that capture disease progression and can be used in future clinical trials.MethodsPatients, invited by their treating physicians or from the national neuromuscular database, and invited family members, were examined twice, 20 months apart, using fixed dynamometry, MRC grading, maximum bite force and isometric tongue strength, Motor Function Measure (MFM), 10-step stair test, maximum swallowing-, chewing-, and speech-tasks and quality of life assessments.ResultsDisease progression was captured by 8 out of 18 measures over 20 months in forty-three genetically confirmed OPMD patients. The largest deterioration was seen in deltoid muscle strength (-27% (range -17 - -37%)), followed by the quadriceps (-14% (range -6 - -23%)), iliopsoas (-12.2%), tongue (-9.9%) and MRC sum-score (-2.5%). The 10-step stair test (-12.5%), MFM part D1 (-7.1%), and maximum repetition rate of /pa/ (-5.3%) showed a significant decrease as well (all p<0.05). Domain 'Physical functioning' of the SF-36 Health Survey significantly deteriorated (p=0.044). No relationship was found between disease progression and genotype or disease duration (p>0.05).ConclusionsDespite the slow disease progression of OPMD, this study showed that several outcome measures detected progression within 20 months. The deltoid muscle strength, measured by fixed dynamometry, showed the greatest decline. This longitudinal data provides clinical outcome measures that can be used as biomarkers in future clinical trials.