D.P.1.02 A Robust Tool to Quantify Disability in Patients Affected by Facioscapulohumeral Muscular Dystrophy

Objective: To propose a homogeneous approach to collect clinical informations suitable for statistical analysis in patients affected by facioscapulohumeral muscular dystrophy (FSHD). To validate a standardized disability score specific for this disease. Introduction: FSHD is an autosomal dominant myopathy characterized by extreme clinical variability. The disease is causally associated with deletion of repetitive elements, named D4Z4, located at the chromosome 4q. Methods and results: A dedicated clinical form was designed to investigate FSHD patient’s clinical history and to obtain the functional quantification of muscle weakness through a questionnaire that allows to assign a disability score specifically modified for FSHD patients, ranging from 0 to 15. The final score is the result of the evaluation of six distinct districts (facial shoulder arm leg hip abdominal muscles). To test FSHD score robustness towards inter-observers’ variability, 70 patients were studied. Each patient was evaluated simultaneously by at least five neurologists from any of the 11 institutes involved in the present study. Each clinician attributed independently a FSHD disability score. The study was conducted through five meetings and 482 forms were collected. Statistical analysis was performed to assess the degree of concordance between clinicians’ evaluations using Landis and Koch’s interpretive scale for k values. The concordance was almost perfect for all the districts examined. Conclusion: We demonstrated that the disability score generated by the patient’s clinical evaluation does not vary depending on the examiner, being the statistical concordance demonstrated by a near perfect agreement (overall k = 0.92). We propose that the FSHD disability score generated will be a useful tool for genotype/phenotype correlations in FSHD. In addition, in view of the Italian register of FSHD we expect the use of the FSHD disability score to provide information about the natural history of the disease.