Different drug survival of first line tumour necrosis factor inhibitors in radiographic and non-radiographic axial spondyloarthritis: a multicentre retrospective survey

Objective Good drug survival of tumour necrosis factor inhibitors (TNFi) has been shown in axial spondyloarthritis (axSpA) patients treated in real-life setting. However, few studies have compared drug survival of the first TNF inhibitor between radiographic axSpA (r-axSpA) and non-radiographic axSpA (nr-axSpA) patients in real-world clinical practice. The aim of this work was to evaluate the effectiveness by assessing the retention rate of first-line TNFi in r-axSpA and nr-axSpA patients. Baseline predictive factors for TNFi discontinuation were also evaluated. Methods We retrospectively assessed axSpA patients, who underwent first line therapy with TNFi. Demographic and clinical data was obtained through structured interview, review of medical records and physical examination. Disease activity indices such as the Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Ankylosing Spondylitis Disease Activity Score evaluating C Reactive Protein (ASDAS-CRP), Leeds Enthesitis Index (LEI) were assessed at baseline. Moreover Health Assessment Questionnaire-Disability Index (HAQ), erythrocyte sedimentation rate (ESR, mm/h), CRP (mg/dl) and HLA-B27 were recorded as well. Data on x-ray and magnetic resonance imaging of the sacroiliac joints were also collected. Drug retention rates were analysed using Kaplan-Meier curves; log-rank test was performed to demonstrate differences in the survival functions. Cox regression models were used to estimate the inference of several disease and clinical characteristics on drug discontinuation. Results Drug survival of first- line TNFi was significantly lower in patients who had nr-axSpA than in those with r-axSpA (p=0.005). HLA-B27 frequency was higher in patients with x-ray sacroiliitis than in those with nr-axSpA (p=0.01) as well as mean CRP serum level (p=0.0001), whereas both mean BASDAI and LEI score were higher in patients with nr-axSpA than in those with r-axSpA (p=0.018 and p=0.007, respectively). Global retention rate in our cohort was 60.34% with mean survival time (MST) of 58.68 months (95% CI 47.93-69.42). MST for patients diagnosed with r-axSpA was 66.79 months (95% CI 53.54-80.04) and 39.05 months (95% CI 24.12-53.99) for those with nr-axSpA. Moreover, nr-axSpA (HR 1.620), higher BMI (HR 1.093) and BASFI, (HR 1.192) had an impact on drug discontinuation, whereas HLA-B27 presence (HR. 0.523) had protective effect. Conclusion Effectiveness of TNFi, seems to be lower in nr-axSpA patients than in those with r-axSpA. In addition obesity and functional disability negatively impact the persistence on first line TNFi in axSpA patients in real life setting