Increasing Rates of Arthroplasty for Psoriatic Arthritis in the United Kingdom Between 1995 and 2010

Arthroplasty requirements among patients with psoriatic arthritis (PsA) are not well known. This information is important to clinical and policy stakeholders for health-system planning and may serve as a surrogate for estimation of the efficacy of disease-modifying therapy.

We utilized The Health Improvement Network (THIN), a large general practice medical records database in the UK, to assess rates of primary total arthroplasty among patients with PsA and the general population between the years 1995 and 2010. Linear regression was used to estimate arthroplasty rates for the 2 cohorts during the study period, and Poisson regression was used to determine age- and sex-adjusted incidence rate ratios (IRRs) between the PsA and general population cohorts.

We identified 5,619 patients with incident PsA and 5,090,814 eligible patients from the general population between 1995 and 2010. In total, 187 primary total arthroplasties were documented in patients with PsA, and 80,163 primary total arthroplasties were documented in the general population. A trend of increasing arthroplasty rates was observed for both the PsA (R² = 0.809; P < 0.0001) and general population (R² = 0.890; P < 0.0001) cohorts during the study period. After adjustment for age and sex, patients with PsA had a first arthroplasty incidence rate that was twice that of the general population (IRR 2.01 [95% confidence interval 1.73-2.34]; P < 0.0001), notably beyond the year 2003 when biologic therapies were introduced.

Both the general population and patients with PsA have experienced increasing rates of first arthroplasty from 1995 to 2010, although the overall incidence rate was significantly higher for those with PsA.