Figure 1.

Study sample. Participants from the multiple sclerosis clinical series and the Mayo Clinic Cohort Study of Oophorectomy and Aging-2. The multiple sclerosis clinical series was enriched for progressive multiple sclerosis. Of the 979 patients, 233 responded to the survey (163 females, 70 males). Of the 163 respondent females with multiple sclerosis, 142 were postmenopausal. The control females from the general population were derived from the Mayo Clinic Cohort Study of Oophorectomy and Aging-2. After excluding patients with multiple sclerosis (n = 17), postmenopausal control females (n = 396) were randomly 3:1 matched for year of birth to postmenopausal females from the multiple sclerosis study cohort. *A 3:1 matching was available for 128 cases, 2:1 was available for three cases, 1:1 was available for six cases and no controls were available for five cases. By excluding the five multiple sclerosis patients without matching controls, case–control analyses were conducted in 137 postmenopausal females with multiple sclerosis and 396 year of birth matched control females