Economic evaluation of damage accrual in an international SLE inception cohort using a multi-state model approach

Abstract

OBJECTIVES: There is a paucity of data regarding healthcare costs associated with damage accrual in systemic lupus erythematosus (SLE). We describe costs associated with damage states across the disease course using multi-state modeling. METHODS: Patients from 33 centres in 11 countries were enrolled in the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort within 15 months of diagnosis. Annual data on demographics, disease activity, damage (SLICC/American College of Rheumatology (ACR) Damage Index [SDI]), hospitalizations, medications, dialysis, and selected procedures were collected. Ten-year cumulative costs (Canadian dollars) were estimated by multiplying annual costs associated with each SDI state by the expected state duration using a multi-state model. RESULTS: 1687 patients participated, 88.7% female, 49.0% of Caucasian race/ethnicity, mean age at diagnosis 34.6 years (SD 13.3), and mean follow up 8.9 years (range 0.6-18.5). Annual costs were higher in those with higher SDIs (SDI ≥ 5: $22 006 2019 CDN, 95$16 662, $27 350 versus SDI=0:$1833, 95% CI $1134,$2532). Similarly, 10-year cumulative costs were higher in those with higher SDIs at the beginning of the 10-year interval (SDI ≥ 5: $189 073, 95$142 318, $235 827 versus SDI=0:$21 713, 95% CI $13 639,$29 788). CONCLUSION: Patients with the highest SDIs incur 10-year cumulative costs that are almost 9-fold higher than those with the lowest SDIs. By estimating the damage trajectory and incorporating annual costs, damage can be used to estimate future costs, critical knowledge for evaluating the cost-effectiveness of novel therapies