Differences Between Females and Males in the Diagnostic Delay and Clinical Course of Thymectomised Myasthenia Gravis

Myasthenia gravis (MG) is an autoimmune disease presenting typically at an earlier age in females compared to males. However, whether sex affects the diagnostic delay and clinical course of MG has not been extensively explored in systematic cohorts.

We conducted a retrospective single-center cohort study on 251 thymectomized MG patients, including 124 males and 127 females. Mean follow-up was 10.7 (±9.1) years post-thymectomy. We analyzed factors associated with longer diagnostic delay and the type of first-onset symptoms (ocular vs. generalized). For 195 patients with nonthymomatous generalized MG (gMG) pre-thymectomy, we estimated the effect of diagnostic delay, symptoms at onset, and sex on reaching complete stable remission (CSR) or minimal need for medication (MNM) during postoperative follow-up. We also assessed their effect on the overall need for in-hospital treatments, immunosuppressant use, and pyridostigmine dose at the last follow-up visit.

Generalized symptoms at onset were more frequent for females than for males (n = 90, 70.9% vs. n = 65, 52.4%, respectively; p < 0.001). Diagnostic delay was significantly longer in females (6.0 months [0-117.5] vs. 3.2 months in males [0.1-84.0]; p = 0.012). First-onset symptoms and diagnostic delay did not affect the post-thymectomy prognosis of gMG. However, females achieved CSR (17.1% vs. 4.5%; p = 0.006) and MNM (30.8% vs. 16.9%; p = 0.029) more frequently and required fewer in-hospital treatments (40.6% vs. 55.2%; p = 0.010) and immunosuppressants (29.2% vs. 61.7%; p < 0.001) than males.

We report sex-related differences in symptoms at MG onset, length of diagnostic delay, and prognosis, the origins of which should be further studied.