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.