Impact of Thymectomy on Crisis Incidence and Quality of Life amongst Generalised Myasthenia Gravis Patients

Abstract

Background: Thymectomy, combined with corticosteroids, immunosuppressive agents, and cholinesterase inhibitors, has been accepted as the standard treatment for myasthenia gravis (MG) patients. Data on the effect of thymectomy on occurrence of myasthenic crisis are few.

Objectives: To assess the long-term impact of thymectomy in patients with generalized Myasthenia gravis (GMG) in terms of occurrence of myasthenia crisis and quality of life.

Methods: A retrospective analysis of 274 clinical records of patients diagnosed with myasthenia gravis (MG) in Nizam's institute of medical sciences (NIMS), a tertiary level teaching hospital between January 2000 and December 2015 was done. Severity of the disease was assessed using Myasthenia Gravis Foundation of America (MGFA) classification and quantitative myasthenia gravis (QMG) score. Myasthenia crisis was diagnosed in our patients when they required ventilator assistance due to respiratory failure caused by muscle weakness (MGFA class V). Quality of life (QoL) was assessed.

Results: Of 230 cases included in the final analysis, 108 (46.9%) underwent thymectomy. Posttreatment crisis occurred in 53.3% of the nonthymectomy subjects, and 25.9% of thymectomy group (P < 0.001). In multivariate logistic regression analysis, after controlling for the effect of gender, age at diagnosis and grade of the disease, the odds ratio of myasthenic crisis in people with thymectomy was 0.186.(95% CI 0.087 to 0.387, P = 0.001). No statistically significant differences were observed in quality of life scores between thymectomy and nonthymectomy groups, either before (P = 0.86) or after surgery (P = 0.939).

Conclusions: The odds of myasthenia crisis was lesser in people, who underwent thymectomy even after controlling for MGFA grade and other potential confounders but no significant differences in quality of life were found with thymectomy.

Keywords: Myasthenia crisis; myasthenia gravis; quality of life; thymectomy.