Associated Factors with the Severity of Hip Involvement in Spondyloarthritis and Efficacy of TNF α Inhibitors in these Patients

Introduction: Hip involvement in patients with spondyloarthritis is responsible for disability and functional impairment. Its treatment is not codified. Our study aimed to determine the associated factors with moderate and severe hip involvement in spondyloarthritis patients. It also aimed to assess the efficacy of tumour necrosis factor inhibitors (TNFi) on hip disease. Methods: We conducted a cross-sectional study, including 44 spondyloarthritis patients with hip involvement. Hip involvement was diagnosed based on radiographic findings. We assessed the following parameters: Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Radiology Index (BASRI), patient global assessment (PGA), and Lequesne index. We compared these parameters and the mean radiographic joint space width between the time of the study to those right before the use of TNFi. Results: Hip involvement was bilateral in 31 patients. The mean age was 44.56±12.21 years. There were 29 men. Severe and moderate involvement (BASRI-hip>3) was reported in 21 hips from 75 affected. These patients were older and had longer diagnosis delays than patients with BASRI- hip<3. They had a higher body mass index and more limited spine mobility (BASMI). Functional hip impairment assessed by the Lequesne index was higher in these patients. TNFi prescribed in 23 patients with hip involvement, led to an improvement in the Lequesne index (12.75 vs 7.5, p: 0.001) and PGA (7 vs 2, p: 0.001). However, the mean joint space width remained unchanged (3.8 vs 3.7mm, p: 0.532). Conclusion: Our study showed that higher body mass and Lequesne indexes are associated with moderate and severe hip involvement. TNFi may improve both the Lequesne index and PGA and stabilize the radiological findings.