Decrease in the incidence of total hip arthroplasties in patients with rheumatoid arthritis – results from a well-defined population in south Sweden.
INTRODUCTION: One aim of modern pharmacologic treatment in rheumatoid arthritis (RA) is to prevent joint destruction and reduce the need for surgery. Our purpose was to investigate secular trends in the incidence of primary total hip and knee arthroplasties in a well defined sample of patients with RA. METHODS: Prevalent cases with RA in 1997 and incident cases 1997-2007 in a community based register in Malmo, south Sweden, were included. Based on a structured review of the medical records, patients were classified according to the 1987 ACR criteria for RA. This cohort was linked to the Swedish Hip Arthroplasty Register (through December 2006) and the Swedish Knee Arthroplasty Register (through October 2007). Patients with a registered total hip or knee arthroplasty before 1997 or before RA diagnosis were excluded. Incidence rates for the period of introduction of TNF inhibitors (1998-2001) were compared to the period when biologics were part of the established treatment for severe RA (2002-2006/2007). RESULTS: In the cohort (n=2164; 71% women) a primary hip arthroplasty was registered for 115 patients and a primary knee arthroplasty for 82 patients. The incidence of primary total hip arthroplasties decreased from the period 1998-2001 [12.6/1000 person-years(pyr)] to 2002-2006 (6.6/1000 pyr) rate ratio (RR) 0.52; 95% confidence interval (CI) 0.35-0.76. There was a trend towards an increase of primary knee arthroplasties (incidence 4.8/1000 pyr vs. 6.8/1000 pyr- RR 1.43; 95% CI 0.89-2.31). CONCLUSIONS: Our investigation shows a significant decrease in the incidence of total hip arthroplasties in patients with RA after 2001. Possible explanations include a positive effect on joint damage from more aggressive pharmacological treatment.