Endocrine Abstracts

JOINT1967

Objective: Axial spondyloarthritis (axSpA), especially radiographic axSpA, is more frequently observed in males, and the role of testosterone in the etiology remains controversial. Our study aims to determine the prevalence of axSpA in people with gender dysphoria (GD) undergoing gender- affirming hormone therapy (GAHT) and to assess whether testosterone therapy increases disease prevalence in female-to-male (FtM) GD.

Materials and Methods: Using a structured questionnaire prepared by the rheumatology department, the medical histories of people receiving GAHT were collected in face-to-face or telephone interviews. HLA-B27 and C-reactive protein (CRP) levels were determined in participants who had been suffering from chronic back pain for more than three months and whose symptoms started before the age of 45, in line with the entrance criteria of The Assessment of SpondyloArthritis International Society (ASAS) classification for axSpA. X-rays of the sacroiliac joints and magnetic resonance imaging (MRI) were also performed.

Results: In the first step, a total of 280 individuals with GD were approached, and 250 (61 male-to female (MtF), 189 FtM) participated in the study. Inflammatory back pain was identified in 6% of participants with GD (13 FtM, 2 MtF). All patients were HLA-B27 negative. The sacroiliac joint radiographs of three FtM GD individuals showed findings suggestive of axSpA, but they did not meet the modified New York criteria for radiographic axSpA. Three FtM GD individuals with suspicious radiologic findings had chronic structural lesions suggestive of chronic sacroiliitis on sacroiliac MRI. In the second step, we also examined 41 FtM GD individuals for chronic back pain before starting GAHT. At baseline, 10 subjects reported chronic back pain, of which only 2 had inflammatory back pain, while the remaining 8 had mechanical back pain. After one year of GAHT only one individual continued to suffer from chronic back pain. Remarkably, this person was one of the two individuals who had reported inflammatory back pain before starting GAHT.

Conclusion: According to the ASAS criteria, the prevalence of inflammatory back pain in this cohort was 6%, similar to the general population. Although none of the patients met the modified New York criteria for radiographic axSpA, three FtM GD had radiographic findings suggestive of sacroiliitis. early-stage axSpA. Although there is ongoing debate about whether non-radiographic axSpA is an early stage of radiographic axSpA or whether these 2 entities are mutually exclusive, longitudinal follow-up of these individuals to monitor disease progression is warranted.