Remission rate after thymectomy in myasthenia gravis when the bias of immunosuppressive therapy is eliminated

The clinical course of all 86 myasthenia gravis (MG) patients who were thymectomized at Sahlgrenska Hospital between 1955 and 1980 was evaluated in order to estimate what the rate of complete clinical remission (with or without anticholinesterase medication) would be without immunosuppressive (IS) therapy; 19 of 73 patients without thymoma received IS therapy. A suitable way of dissociating the course after thymectomy from the influence of IS therapy is the Markov method. The calculated probability of remission was 0.18, 0.35, 0.43, 0.53 and 0.56 in the 0-1, 2-3, 4-5, 5-10 and more than 10-year periods after thymectomy. A similar result (53 +/- 7%) was obtained by a life-table method with censoring of IS-treated patients when they received such therapy. Time to remission was significantly shorter for patients with age of MG onset before 35 years. Timing of IS therapy after thymectomy is discussed, considering the post-thymectomy remission rate.