The systemic lupus erythematosus tri-nation study: longitudinal changes in physical and mental well-being

Objective. We have shown that SLE patients in Canada and the UK incurred 20% and 13% lower health costs than those in the US, respectively, but did not experience worse outcomes as expressed by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. We now compare change in quality of life in these patients. Patients and methods. Seven hundred and fifteen SLE patients (Canada 231, US 269, UK 215) completed the SF-36 annually over four years. The annual change in the SF-36 Physical and Mental Component Summary (PCS and MCS) scores over the course of the study were summarized by estimating a linear trend for each individual patient using hierarchical modelling. Cross-country comparison of the slopes in the PCS and MCS scores was then performed using simultaneous regressions. Results. The estimated mean annual changes (95% credible interval [CrI]) in the PCS scores in Canada, the US, and the UK were 0.18 (-0.07, 0.43), -0.05 (-0.27, 0.17), and 0.03 (-0.20, 0.27), respectively; the mean annual changes in the MCS scores were 0.15 (-0.04, 0.34), 0.23 (0.09, 0.37), and 0.08 (-0.10, 0.27), respectively. Regression results showed that the mean annual changes in PCS and MCS scores did not substantially differ across countries. Conclusion. Quality of life remained stable across countries. Despite Canadian and British patients incurring lower health costs, on average, patients experienced similar changes in physical and mental well-being.