Is there any gender-specific difference in the cut-off values of ankylosing spondylitis disease activity score in patients with axial spondyloarthritis?

AIM: To assess the validity of Assessment in Spondyloarthritis International Society (ASAS) endorsed Ankylosing Spondylitis Disease Activity Score (ASDAS) C-reactive protein (-CRP) and ASDAS erythrocyte sedimentation rate (-ESR) in axial spondyloarthritis (axSpA) and to estimate the cut-off values for male and female patients with axSpA.

METHODS: Patients with axSpA were assessed for disease activity, functions, mobility and AS Quality of Life (ASQoL) and pain. The discriminant ability of ASDAS versions was assessed using standardized mean differences. Optimal cut-off values of ASDAS versions were calculated.

RESULTS: Patients with axSpA were included (196 AS, 164 non-radiographic axSpA). ASDAS versions and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) had good correlations with patient's global (PtG) and physician's global (PhG) assessment in both groups; however, men had relatively higher coefficients. Women had significantly higher pain, ASQoL, ASDAS-ESR, BASDAI item scores, PtG, PhG and ESR. Discriminant abilities of ASDAS-CRP, ASDAS-ESR and BASDAI were similar in men and women regarding low and high disease activity. ASDAS cut-offs are quite similar in both genders and in accordance with predefined values. The cut-offs for ASDAS-ESR were relatively lower than ASDAS-CRP and women tend to have higher cut-offs than men.

CONCLUSION: The construct validity of ASDAS-CRP to discriminate low and high disease activity and cut-off values are similar in male and female patients with axSpA; however, cut-offs for ASDAS-ESR need to be defined.