THU0407 Baseline Results from Proof – A 5-Year Observational Study of Long-Term Disease Outcome in Axial Spondyloarthritis
Authors: R.D. Inman, J. Sieper, D. Poddubnyy, S. Akar, S. Munoz-Fernandez, M. Hojnik
Journal: Annals of the Rheumatic Diseases (2016)

<h3>Background</h3> Axial spondyloarthritis (axSpA), encompassing ankylosing spondylitis (AS) and non-radiographic axSpA (nr-axSpA) without advanced structural lesions in the sacroiliac joints (SIJ), is a relatively new disease concept. The natural disease course of axSpA, including progression of structural damage over time, has not yet been systematically studied in large patient (pt) groups. <h3>Objectives</h3> To report the baseline data of PROOF, a large study currently being conducted in 29 countries across the world, evaluating long-term outcomes in pts with axSpA classified by ASAS criteria. <h3>Methods</h3> PROOF is a multi-country prospective observational study evaluating axSpA pts in rheumatology clinical practice over 5 years. Pts with axSpA fulfilling ASAS classification criteria were eligible, if diagnosed ≤12 months prior to study enrolment. Investigator9s confidence with the diagnosis of axSpA is ascertained on a numeric rating scale (NRS 0–10) at enrolment and end of follow-up. Assessments of disease activity (BASDAI, ASDAS-CRP), physical function (BASFI), quality of life (SF-12v2), productivity (WPAI-SHP), and pelvic X-ray are scheduled at yearly follow-up visits. X-rays are graded according to NY criteria by local and central readers. <h3>Results</h3> 2084 pts with axSpA fulfilling ASAS criteria have been enrolled in PROOF study, 1259 pts with AS (60%) and 825 pts with nr-axSpA (40%) according to the investigators. The level of confidence with the diagnosis of axSpA was 8.7±1.8. The imaging criterion was fulfilled by 85% of pts (40% MRI, 51% X-ray, 9% both), 15% of pts were classified through the clinical arm. HLA-B27 was tested in 85% of pts and found to be positive in 68% of cases (70% with AS and 60% with nr-axSpA). Overall, pts were in their mid-thirties, had a long delay in referral to rheumatologist and recently diagnosed axSpA. Comparison of demographic and clinical characteristics between pts with AS and nr-axSpA is shown in Table 1. Pelvic x-rays were reportedly done in 1635 (78%) pts within 6 months of the baseline visit; to date both local and central readers have scored x-rays of 1344 pts (82% of available). Of the 1344 pts, 83.3% retained their classification (AS or nr-axSpA) after the central reading, while 16.7% were classified differently. Based on the kappa value, there was a substantial agreement on the grading of x-rays between the local and central readers: kappa=0.63 (95% CI, 0.59–0.68). <h3>Conclusions</h3> PROOF is the largest observational study in pts with axSpA classified by ASAS criteria so far. It provides insights into the clinical practice worldwide and aims to assess long-term outcomes of axSpA. Baseline results confirmed comparable clinical features and disease burden between AS and nr-axSpA, highlighted a long delay in referral to rheumatologists, and showed a good agreement between the SIJ x-ray grading by local and central readers. <h3>Acknowledgement</h3> AbbVie funded the PROOF study, contributed to its design and participated in data collection, analysis and interpretation of the data, and in writing, review, and approval of the publication. Medical writing support was provided by Deepa Venkitaramani, PhD, of AbbVie. <h3>Disclosure of Interest</h3> R. Inman Grant/research support from: AbbVie, Amgen, Janssen, Pfizer, and UCB, Consultant for: AbbVie, Amgen, Janssen, Pfizer, and UCB, Speakers bureau: AbbVie, Amgen, Janssen, Pfizer, and UCB, J. Sieper Grant/research support from: AbbVie, Merck, Pfizer, and UCB, Consultant for: AbbVie, Merck, Pfizer, and UCB, Speakers bureau: AbbVie, Merck, Pfizer, and UCB, D. Poddubnyy Grant/research support from: AbbVie, BMS, Janssen, MSD, Novartis, Pfizer, Roche, and UCB, Consultant for: AbbVie, BMS, Janssen, MSD, Novartis, Pfizer, Roche, and UCB, Speakers bureau: AbbVie, BMS, Janssen, MSD, Novartis, Pfizer, Roche, and UCB, S. Akar Grant/research support from: AbbVie, BMS, MSD, Novartis, Pfizer, Roche and UCB, Consultant for: AbbVie, BMS, MSD, Novartis, Pfizer, Roche and UCB, Speakers bureau: AbbVie, BMS, MSD, Novartis, Pfizer, Roche and UCB, S. Munoz-Fernandez Grant/research support from: Abbvie, BMS, Janssen, MSD, Pfizer, Roche, and UCB, Consultant for: Abbvie, BMS, Janssen, MSD, Pfizer, Roche, and UCB, Speakers bureau: Abbvie, BMS, Janssen, MSD, Pfizer, Roche, and UCB, M. Hojnik Shareholder of: AbbVie, Employee of: AbbVie