Survival of patients with myasthenia gravis after thymectomy. Analysis of 100 cases

In order to evaluate the survival of patients with myasthenia gravis (MG) after thymectomy (T), 100 patients with MG in which T had been performed between 1967 and 1995 were studied. Patients were divided into different groups for their analysis: patients with thymoma (TI), 22 cases; and patients without thymoma (NTI), 78 cases. In addition those patients belonging to the latter group were further separated according to the date of their surgery into two other subgroups: patients operated before 1980 (A80), 43 cases; and after 1980 (D80), 35 cases; trying to evaluate the prognostic implications of the therapeutical advances achieved over the last 15 years. The population studied was composed mainly of women (78%) but with a slight predominance of men in TI. The mean age was 29.47 years (range 10-70) for the entire population, with a tendency toward older ages in TI (mean 46 years, range 23-70). The mean follow-up period was 4.3 years (range 0.08-23.2) without significant differences between TI and NTI. The results showed that the overall mortality rate was 16/100 (16%) [Fig. 1], with nine of those deaths corresponding to TI (9/22, 40.91%) and only the remaining seven to NTI (7/78, 8.97%). These differences in mortality rate between TI and NTI were statistically significant in all the specific times of follow-up analized up to 10 years after surgery (p < 0.05) [Fig. 2]. Notoriously, all deaths in NTI occurred in the A80 subgroup giving a p value < 0.001 when compared with D80 [Fig. 3]. In terms of morbidity, 55/100 (55%) reached complete clinical remission (CCR) defined by the complete absence of symptoms related to MG: 8/22 (36.36%) in TI and 47/78 (60.25%) in NTI [Fig. 4]. Most interestingly the differences were statistically significant (p < 0.01) when the rates of CCR in A80 and D80 were compared for all the times assessed [Fig. 5-6-7-8]. It can be concluded that the best results in survival in MG after T are obtained in patients without thymoma and also that the benefits of the rational use of modern therapeutic modalities, including surgery and immunosuppression with drugs, can offer those patients high possibilities of leading completely normal lives.