Despite known gender differences in the severity of axial spondyloarthritis (axSpA) and findings demonstrating clear differences in early disease, researchers found that key diagnostic markers such as human leukocyte antigen-B27 (HLA-B27) and sacroiliac joint imaging positivity remained important diagnostically in both men and women. They concluded that different gender-specific approaches to diagnosis are not required, according to a report published in Arthritis Research & Therapy.
In the first study of its kind, investigators sought to examine whether men and women exhibit phenotypic differences at the time of diagnosis that might necessitate individualized diagnostic strategies. An analysis of the Spondyloarthritis Caught Early (SPACE) trial — an ongoing study examining patients with unexplained chronic back pain — considered baseline data from 719 patients (mean age at pain onset, 29.0 years; 62% women; mean pain duration, 13.2 months). Diagnostic workup included clinical evaluation, standard serologies and x-rays and magnetic resonance imaging (MRI) of the sacroiliac joint. Gender differences in patients with confirmed axSpA diagnoses were evaluated, including multivariable regression modeling with odds ratio (OR) calculation for the entire chronic back pain cohort as well as for the axSpA subgroup.
Diagnoses of axSpA were confirmed in 146 of 275 men (53.1%) and 155 of 444 women (34.9%), indicating that men were twice as likely to receive such a diagnosis (OR, 2.1; 95% CI, 1.5-2.9). While symptom duration was similar in both genders, men were diagnosed at a younger age than women (mean age, 27.4 vs 29.5 years; P =.02).
Most disease features occurred at similar rates in both men and women, with the exception of imaging positivity (78% vs 64%; P =.007) and HLA-B27 positivity (80% vs 60%; P <.001). However, both imaging and HLA-B27 positivity remained more prevalent in women with axSpA compared with patients without axSpA, regardless of whether the comparison was made with men without axSpA (11% and 34%, respectively; P <.01) or women without axSpA (7% and 23%, respectively; P <.01).
Multivariable regression analysis revealed that imaging and HLA-B27 positivity in both genders were independently associated with a diagnosis of axSpA (P <.001). In addition, in men with disease, elevated C-reactive protein or erythrocyte sedimentation rate was associated with a positive diagnosis (P =.05). Also, in patients with confirmed disease, HLA-B27 positivity (OR, 1.8; 95% CI, 1.0-3.3; P =.04) and being male (OR, 1.8; 95% CI, 1.0-3.1; P =.05) were independently associated with positive findings on sacroiliac joint radiograph or MRI.