Gender characterization in a large series of Brazilian patients with spondyloarthritis

An increasing number of women have been diagnosed with spondyloarthritis (SpA) in recent decades. While a few studies have analyzed gender as a prognostic factor of the disease, no studies have addressed this matter with a large number of patients in South America, which is a peculiar region due to its genetic heterogeneity. The aim of the present study was to analyze the influence of gender on disease patterns in a large cohort of Brazilian patients with SpA. A prospective study was carried out involving 1,505 patients [1,090 males (72.4%) and 415 females (27.6%)] classified as SpA according to the European Spondyloarthropaties Study Group criteria who attended at 29 reference centers for rheumatology in Brazil. Clinical and demographic variables were recorded and the following disease indices were administered: Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Radiologic Index (BASRI), Maastricht Ankylosing Spondylitis Enthesitis Score (MASES), and Ankylosing Spondylitis Quality of Life (ASQoL). Ankylosing spondylitis (AS) was the most frequent disease in the group (65.4%), followed by psoriatic arthritis (18.4%), undifferentiated SpA (6.7%), reactive arthritis (3.3%), arthritis associated to inflammatory bowel disease (3.2%), and juvenile SpA (2.9%). The male-to-female ratio was 2.6:1 for the whole group and 3.6:1 for AS. The females were older (p < 0.001) and reported shorter disease duration (p = 0.002) than the male patients. The female gender was positively associated to peripheral SpA (p < 0.001), upper limb arthritis (p < 0.001), dactylitis (p = 0.011), psoriasis (p < 0.001), nail involvement (p < 0.001), and family history of SpA (p = 0.045) and negatively associated to pure axial involvement (p < 0.001), lumbar inflammatory pain (p = 0.042), radiographic sacroiliitis (p < 0.001), and positive HLA-B27 (p = 0.001). The number of painful (p < 0.001) and swollen (p = 0.006) joints was significantly higher in the female gender, who also achieved higher BASDAI (p < 0.001), BASFI (p = 0.073, trend), MASES (p = 0.019), ASQoL (p = 0.014), and patient's global assessment (p = 0.003) scores, whereas the use of nonsteroidal anti-inflammatory drugs (p < 0.001) and biological agents (p = 0.003) was less frequent in the female gender. Moreover, BASRI values were significantly lower in females (p < 0.001). The female gender comprised one third of SpA patients in this large cohort and exhibited more significant peripheral involvement and less functional disability, despite higher values in disease indices.