Comparative analysis of therapeutic options used for myasthenia gravis.

OBJECTIVE: To compare clinical and economic outcomes following plasma exchange (PLEX) and intravenous immunoglobulin (IVIG) in U.S. patients with primary diagnoses of myasthenia gravis (MG).

METHODS: Our cohort was identified from the Nationwide Inpatient Sample database for years 2000-2005 using codes from the International Classification of Diseases, 9th edition. Multivariate regression analyses were used to identify predictors of mortality, complications, length of stay, and total inpatient cost.

RESULTS: Among 1,606 hospitalized patients, the unadjusted mortality rate of MG crisis remained higher than those without crisis (0.44% vs 4.44%, p < 0.001), as well as the unadjusted complication rate (26.36% vs 11.23%, p < 0.001). MG crisis patients receiving PLEX had significantly more complications than those receiving IVIG (30.06% vs 14.79%, p < 0.001). Among the whole cohort, adjusted mortality and complication rates were not significantly different between the treatment groups (p > 0.05). Acute respiratory failure, major cardiac complications, and acute renal failure were associated with an increased mortality rate (p < 0.001). Age and respiratory failure were associated with an increased complication rate (p < 0.001). Length of stay was significantly longer for MG (6 vs 4 days, p < 0.001) and MG crisis (10 vs 5 days, p < 0.001) patients receiving PLEX. Inpatient costs were higher for MG ($26,662 vs $21,124, p < 0.01) and MG crisis ($53,801 vs $33,924, p < 0.001) patients receiving PLEX.

INTERPRETATION: Compared to PLEX, IVIG appears of similar clinical (mortality and complications) and perhaps of superior economic (length of stay and total inpatient charges) outcomes in the treatment of MG. Elderly and those with complex comorbid diseases including acute respiratory failure may be better treated with IVIG.