Background Sustained clinical remission is one of the key benchmarks for treatment over the long term. Identification of factors that predict this endpoint may help in the selection of AS patients for treatment with anti-TNF and appropriate monitoring of response. There has been minimal data reported on factors that influence sustained remission in AS and there is no data evaluating MRI parameters of inflammation and structural damage.
Objectives 1. To determine the factors predictive of sustained clinical remission on anti-TNF therapy in real world practice. 2. To determine the role of MRI parameters of inflammation and structural damage at baseline and after treatment on sustained clinical remission.
Methods In the FOllow-up Research Cohort in AS (FORCAST), AS patients from Northern Alberta attending community and academic practices are assessed for clinical and laboratory outcomes every 6 months, radiography at baseline and 2 years, MRI at baseline, at 3-6 months for patients starting anti-tumor necrosis factor alpha (anti-TNFα), and annually. MRI inflammation was assessed using SPARCC SIJ and Spine scores while structural change was assessed independently using the SSS scores for fat metaplasia, erosion, backfill, ankylosis and the FASSS score for fat metaplasia in the spine. Sustained clinical remission was defined as ASDAS<1.3 at two consecutive 6-monthly visits. We used univariate and multivariate logistic regression to assess patient demographics, smoking, B27, NSAID utilization, and baseline CRP, ASDAS, mSASSS, SPARCC scores, SSS and FASSS scores. We also assessed early attainment post-treatment of CRP<6mg/L, ASADAS<1.3, and SPARCC scores <2 as predictors of future remission.
Results We assessed 323 patients on anti-TNF therapy of mean (SD) age 41.1 (12.7) years, 242 (75%) males), mean (SD) symptom duration 18.1 (11.7) years, and mean (SD) duration of follow up 40.3 (27.4) months, of whom 165 had MRI evaluation. 70 (21.7%) patients attained ASDAS remission after a mean (SD) follow up of 30.4 (23.6) months. In univariate analyses, patients attaining ASDAS remission were younger (p<0.0001), with shorter disease duration (p=0.019), lower mSASSS (p=0.021), lower baseline ASDAS (p=0.006), not current smokers (p=0.009), with minimal evidence of spinal fat metaplasia (FASSS<5) (p=0.043) and post-treatment scores indicating remission of MRI inflammation (SPARCC spine<3 and SIJ <2) (p=0.033), and normalised CRP (p=0.002). In multivariate analyses, age, smoking status, and baseline ASDAS and normalized CRP were the strongest clinical predictors and inclusion of MRI parameters revealed that none were significant.
Conclusions Smoking is a major factor preventing attainment of sustained remission to anti-TNF. Sustained remission is more likely in patients attaining normalised CRP early after treatment.
Disclosure of Interest S. Pedersen: None declared, S. Wichuk: None declared, P. Chiowchanwisawakit: None declared, Z. Zhao: None declared, R. Lambert: None declared, B. Connor-Spady: None declared, D. Spady: None declared, W. Maksymowych Consultant for: Abbvie, Amgen, Eli-Lilly, Janssen, Merck, Pfizer, UCB