OBJECTIVE: Little is known about the long-term costs of lupus nephritis (LN). These were compared between patients with and without LN based on multistate modelling.
METHODS: Patients from 32 centres in 11 countries were enrolled in the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort within 15 months of diagnosis and provided annual data on renal function, hospitalizations, medications, dialysis, and selected procedures. LN was diagnosed by renal biopsy or the American College of Rheumatology classification criteria. Renal function was assessed annually using estimated glomerular filtration rate (eGFR) or proteinuria (ePrU). A multistate model was used to predict 10-year cumulative costs by multiplying annual costs associated with each renal state by the expected state duration.
RESULTS: 1,545 patients participated, 89.3% female, mean age at diagnosis 35.2 years (SD 13.4), 49.0% Caucasian, and mean follow up 6.3 years (SD 3.3). LN developed in 39.4% by the end of follow up. Ten-year cumulative costs were greater in those with LN and an eGFR < 30 ml/min ($310 579 2015 Canadian dollars versus $19 987 if no LN and eGFR > 60 ml/min) or with LN and ePrU > 3 g/d ($84 040 versus $20 499 if no LN and ePrU < 0.25 g/d).
CONCLUSION: Patients with eGFR < 30 ml/min incurred 10-year costs 15-fold higher than those with normal eGFR. By estimating the expected duration in each renal state and incorporating associated annual costs, disease severity at presentation can be used to anticipate future healthcare costs. This is critical knowledge for cost-effectiveness evaluations of novel therapies. This article is protected by copyright. All rights reserved.