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

Abstract

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.