Background/Purpose: The need for orthopaedic surgery in Rheumatoid Arthritis (RA) is the result of failed medical treatment and a surrogate marker for joint destruction. Reliable prognostic markers are currently limited but have a potential role in guiding clinicians in early management decisions.

Methods: Standardised clinical, laboratory and X-ray measures were performed at baseline, prior to DMARD therapy and then yearly in both the Early RA Study (ERAS, n=1465, 1986-1998) and Early RA Network (ERAN, n=1236, 2002-2011), median follow up 18 and 6 years respectively, maximum 25 years. Treatment of patients included disease modifying, steroid and biologic therapies according to standard UK practices for management of hospital based RA patients. Source data of all orthopaedic interventions included clinical datasets (patient reports and medical records from 1986) and national data: Hospital Episode Statistics and the National Joint Registry. Length of follow up was based on the National Death Registry. For analysis, interventions were grouped into major (total large joint replacements), intermediate (mainly synovectomies, arthroplasties and fusion procedures of wrist, hand, hind/forefoot), and minor (mainly soft tissue and tendon surgery).

Results: 1602 procedures were performed in 770 out of 2701 patients (29%).  576 were large joint replacements (mainly of hips and knees) in 354 (out of 2701) patients (13%), 392 intermediate in 221 (8%), 552 minor in 361 (13%), 55 internal fixations for hip fracture in 53 (2%), 9 cervical spine fusions and the remainder were miscellaneous/not classified procedures. 232 (8.6%) patients had more than one major and/or intermediate procedure.  1255 had minimum 10 year follow up (46%) of whom 531 (42%) had orthopaedic surgery.  In univariate analysis, baseline and 1 year Health Assessment Questionnaire (HAQ), Erythrocyte Sedimentation Rate (ESR), high Disease Activity Scores (DAS), erosions and low haemoglobin(HB) all predicted major and intermediate surgery with odds ratios (ORs) all significant around 1.5-2, but these variables were not predictive of minor surgery.  Strongest predictors for major surgery were low HB (OR 2.6, 95% CI 2-3.3), high Body Mass Index (BMI) only for total knee replacements (OR 1.7, 95% CI 1.2-2.4), for intermediate surgery were women (OR 3.2, 95% CI 2.21-4.7), DAS (OR 3.8, 95% CI 2.1-7.0) and RA related shared epitope (SE, OR 1.6, 95% CI 1.0-2.4). For multiple surgery, strongest predictors were erosions (OR 2.7, 95% CI 1.6-4.3), HAQ (OR 2.6, 95% CI 1.6-4.2), HB (OR 3.4, 95% CI 2.3-4.9), ESR (OR 3.1, 95% CI 1.9-4.7), SE (OR 1.9, 95% CI 1.2-3.4), ESR (OR 3.3, 95% CI 2.3-4.8). In Cox regression, sex, onset age and erosions predicted intermediate surgery, and sex, onset age and HB predicted major surgery. 

Conclusion: Orthopaedic surgery is an important and common outcome in RA, not often reported and difficult to predict. HB does not normally perform well as a predictor of outcome in RA, but did for orthopaedic intervention, especially major and multiple surgery.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/an-evaluation-of-prognostic-factors-for-orthopaedic-joint-surgery-in-rheumatoid-arthritis-results-from-two-multicentre-uk-inception-cohorts-1986-2011/