Low-Dose Medication and Long-Term Outcome in Myasthenia Gravis.

OBJECTIVES: Many advances have been made in the diagnosis, treatment, and management of myasthenia gravis (MG) and most patients will eventually progress to experience minimal manifestations (MM) of the disease or remission. However, there is a paucity of literature on medication dosing needed to achieve such a favorable clinical status in the long term. The objective of this article was to (1) study the course of MG and identify clinical predictors of maintenance of eventual disease remission or minimal manifestations and (2) determine if patients on low-dose medications have comparable MG Foundation of America (MGFA) scores and postintervention statuses (PIS) with those on conventional therapeutic dosing.

METHODS: This is a retrospective longitudinal chart review of 74 patients with MG. A subset of 28 of 74 patients diagnosed with MG after 2000 who were followed for at least 3 consecutive years from the year of diagnosis were also analyzed. An annual MGFA score, PIS, medication doses, and thymectomy status were obtained. Remission or MM of disease was defined as MGFA clinical classification <2 that persisted over the past 2 follow-up visits.

RESULTS: Thirty-four of 74 patients were on low-dose medications at last follow-up. There was no statistical difference between medication dosages and MGFA scores. In a subset of 28 patients, 23 (88.5%) with eventual disease remission or MM at last follow-up had an MGFA class <2 at their third year of diagnosis. In contrast, only 3 of 9 subjects with more symptomatic disease had similar results (P = 0.005). In terms of PIS at last follow-up, most patients were either in complete stable remission, pharmacologic remission, or MM status. Most patients (78.3%) had an MGFA class of 0 or 1 at last follow-up; 45% were on low-dose medications.

CONCLUSIONS: Most patients with MG will realize disease stability characterized by either remission or MM status. A significant number of such patients were able to be maintained on low doses of medications to treat MG. The MGFA class at year 3 of diagnosis is a clinical predictor of long-term disease prognosis. There was no statistical difference between medication doses and MGFA scores at last follow-up.