Long-Term Medical Costs and Resource Utilization in Systemic Lupus Erythematosus and Lupus Nephritis: A Five-Year Analysis of a Large Medicaid Population

Objective. To estimate the long-term direct medical costs and health care utilization for patients with systemic lupus erythematosus (SLE) and a subset of SLE patients with nephritis. Methods. Patients with newly active SLE were found in the MarketScan Medicaid Database (1999-2005), which includes all inpatient, outpatient, emergency department, and pharmaceutical claims for more than 10 million Medicaid beneficiaries. The date a patient became newly active was defined as the earliest observed SLE diagnosis code, with a 6-month clean period prior to the diagnosis. This method identified 2,298 patients with a consecutive followup of 5 years. A reference group of patients without SLE was constructed using propensity score matching. Nephritis was assessed based on diagnosis and procedure codes involving the kidney. Results. Mean annual medical costs for SLE patients totaled $16,089 at year 1, which is significantly greater (by $6,831) than that for reference patients. Costs decreased slightly at year 2 but then increased yearly at an average rate of 16% through year 5, to $23,860. SLE patients without nephritis (n = 1,809) had costs $967-3,756 higher than the reference patients. SLE patients with nephritis (n = 489) had costs $13,228-34,907 greater than the reference group. Inpatient visits for the nephritis subgroup were 0.6-1.0 per capita, which are approximately twice the rate for all SLE patients and 3 to 4 times higher than the reference group. Conclusion. SLE is a costly condition to treat. Medical expenses incurred by SLE patients increase steadily over time, particularly for patients with nephritis.