Objective:

To determine if there are treatment differences between males and females with myasthenia gravis (MG).

Background:

Females with MG report worse quality of life and disease severity scores than males. The reason for these differences remains unclear and may be attributable to differences in treatment.

Design/Methods:

We retrospectively reviewed the medical records of people with generalized MG diagnosed and treated at the University of Calgary between 1997 and 2020. We reviewed disease profile, clinical measures and treatment to determine if there were sex differences.

Results:

We identified 388 patients with MG in our clinic database and included 180 people (41.7% female). There were no sex differences in age at symptom onset and diagnosis, comorbidities or antibody status. Myasthenia Gravis Impairment Index (at 1 year; female 20.9 [95%CI=18.1-23.7] vs male 13.9 [12.0-15.9]) and Myasthenia Gravis Quality of Life scores (at 1 year; female 10.1 [95%CI=8.6-11.5] vs male 6.5 [95%CI=5.2-7.8]) were higher in females, suggesting more impairment and dissatisfaction, while Quantitative Myasthenia Gravis score and Myasthenia Gravis Foundation of America clinical classification were similar between sexes. Females were treated with low dose prednisone (<40mg by mouth daily) less frequently than males (68.0% vs 81.9%, p=0.04), however there was no sex difference in the rate of high dose prednisone use (≥ 40 mg by mouth daily; 45.3% vs 47.6%, p=0.88). There was a non-significant trend towards lower rates of steroid-sparing agent use in females (56.0% vs 65.7%, p=0.21). A higher proportion of females were treated with rituximab (24.0% vs 12.4%, p=0.05).

Conclusions:

Females with MG are less likely to be treated with low dose prednisone and more likely to be treated with rituximab than males. Sex differences in treatment approaches may contribute to disparity in disease outcome and QoL measures.