Background Hip involvement is considered an important prognostic factor associated with radiographic progression in ankylosing spondylitis (AS) patients. However, there are no studies regarding hip involvement impact on clinical response and radiographic progression in AS patients under anti-TNF therapy.

Objectives Compare clinical and radiographic progression in AS patients receiving anti-TNF therapy with and without moderate-severe hip involvement.

Methods Forty-seven AS patients referred to receive anti-TNF treatment were included and classified according to baseline hip involvement based on Bath Ankylosing Spondylitis Radiology Hip Index (BASRI-Hip): none-minimal hip disease (hip grade <3) or moderate-severe disease (hip grade ≥3). Demographic data, presence of HLA-B27, extra-articular involvement, DMARD and NSAID use, clinical and laboratorial disease parameters (BASDAI, BASMI, BASFI, ASQol, mSASSS and inflammatory markers) were assessed at baseline and two years after anti-TNF treatment.

Results Thirty-four (72.3%) patients were classified as none-minimal hip disease and 13 (27.7%) as moderate-severe hip involvement. Both groups were similar at baseline considering age, HLA-B27, extra-articular involvement and comedication use. Laboratorial markers (ESR, CRP) and disease parameters (BASDAI, BASFI and mSASSS) showed no difference at baseline. Moderate-severe group had longer disease (10.0±7.6 vs. 14.9±8.6, P=0.002, years), higher BASMI (3.8±2.4 vs. 6.5±2.5, P=0.002) and lower ASQoL (13.7±4.4 vs. 9.9±4.9, P=0.007). After two-years of anti-TNF therapy, both groups presented similar BASDAI response (delta BASDAI, p=0.134; final BASDAI, p=0.324) and an increase in mSASSS [no-minimal involvement: 13.6±18.3 vs. 16.1±19.4, P<0.001); moderate-severe involvement: 21.7±19.9 vs. 28.6±18.5, P=0.003]. At final evaluation patients with moderate-severe hip involvement presented higher mSASSS (28.6±18.5 vs. 16.1±19.4, P=0.02), despite similar delta BASDAI and final BASDAI.

Conclusions Our study provides evidence that hip involvement did not impact on clinical response in AS patients under anti-TNF therapy but may have an effect on radiographic progression of these patients.

Disclosure of Interest None declared