Predictors of and outcomes following orthopaedic joint surgery in patients with early rheumatoid arthritis followed for 20 years.

Objectives: To analyse predictors and outcomes of major orthopaedic surgery in a cohort of RA patients followed for 20 years. Methods: Patients were recruited to the Norfolk Arthritis Register from 1990 to 1994. Demographic and clinical variables (including the HAQ and swollen and tender joint counts) were assessed at baseline; the 2010 ACR/EULAR RA classification criteria were applied. Patients reported incident comorbidities and major orthopaedic joint surgery (replacement, synovectomy, fusion, excision) when reassessed at years 1, 2, 3, 5, 7, 10, 15 and 20. Baseline and time-varying predictors of orthopaedic surgery were assessed using a conditional risk set model, a type of multiple-failure survival analysis. Change in disability after surgery was assessed using weighted mixed-effects linear regression. Results: Of 589 RA patients [median age 56 years (IQR 45-68); 66.7% women] recruited to the Norfolk Arthritis Register with at least one follow-up, 102 reported a total of 180 major surgeries, with hip replacement being the most common (n = 68/180). Patients reporting major surgery had worse functional disability at all time points, but similar swollen/tender joint counts to those without major surgery. Each unit increase in HAQ score was associated with a doubling of the patient's risk of having surgery by the next assessment [hazard ratio 2.11 per unit increase in HAQ (95% CI 1.64, 2.71)]. Patients had worse HAQ scores after surgery than patients not undergoing surgery [β = 0.17 (95% CI 0.03, 0.32)]. Conclusion: HAQ was the strongest predictor of future major surgery. This supports the argument that HAQ should be included in routine clinical assessment.