Fatigue in Myasthenia Gravis patients.

The purposes of this study were to validate psychometric properties of the Myasthenia Gravis Fatigue Scale (MGFS) and to use the MGFS to study the relationship of selected demographic and clinical variables to fatigue in a myasthenia gravis (MG) patient population. The MGFS, an existing scale, was developed to measure fatigue severity in MG patients. A convenience sample of 67 MG patients was approached on return visit to the Neuromuscular Disease Clinic. After giving consent, participants filled out four questionnaires: the MGFS, the Chalder Fatigue Scale, the Center for Epidemiologic Studies-Depression Scale, and a Demographic and Clinical Data Form. Participants' muscle weakness was evaluated using the Modified Quantitative MG Score for Disease Severity assessment form (13 muscles tested). Three days after the clinic visit, a copy of the MGFS was mailed to participants to allow retest at 5 to 7 days after initial testing. Findings showed that the MGFS demonstrated adequate internal consistency and test-retest reliability. In addition, the fatigue severity (MGFS) score correlated moderately with depression. We adjusted for the effect of depression and noted a relationship between the fatigue score and two of nine selected demographic and clinical characteristics--activity restriction and number of years since diagnosis. These results lay the groundwork for further investigation of fatigue in MG patients and identification of mitigating or coping methods.