Reliable disability scale for myasthenia gravis sensitive to clinical changes.

INTRODUCTION: we developed a disability scale to monitor myasthenia gravis (MG) patients, based on degree of function impairment and daily frequency of each symptom. MATERIAL & METHODS: the scale was based on standardized questions and clinical examination. The scale was administered to 12 patients, one or more times, for a total of 22 interviews. Each observation was recorded on videotape and reviewed by five independent observers. The ability of our scale to discriminate clinical changes was also compared with the Osserman classification. RESULTS: our scale showed from substantial to almost perfect inter and intraobserver agreement. Our findings showed that clinically relevant changes not detected by Osserman staging were disclosed by our scale. CONCLUSION: our scale is simple and easy to use in clinical practice. It offers an accurate means of evaluating disability in MG patients and may detect clinically relevant changes in disability. It would therefore be useful to monitor the effects of therapy.