Economic outcomes in patients diagnosed with systemic lupus erythematosus with versus without nephritis: results from an analysis of data from a US claims database.

BACKGROUND: Based on a literature search, there are limited data on the economic burden of systemic lupus erythematosus (SLE), particularly in patients with lupus nephritis.

OBJECTIVE: The objective of this study was to compare health care resource utilization and direct medical care costs over a period of 12 months in patients with a history of SLE with or without nephritis.

METHODS: Patients aged >or=18 years with >or=1 claim for an immunosuppressive/disease-modifying antirheumatic drug, antimalarial agent, NSAID/cyclooxygenase-2 inhibitor, or other SLE-related treatment (eg, opioid and combination analgesic, antianxiety agent, antihyperlipidemic agent, antihypertensive agent, bisphosphonate, vitamin D) dated between January 1, 2007, and December 31, 2007, were identified using a nationally representative, US commercial insurance claims database. The date of the first dispensation of the treatment represented the index date. Patients were required to have >or=2 claims containing a diagnosis of SLE during a 6-month preindex period through 3 months postindex and to have continuous health plan enrollment for 6 months before and 12 months after the index date. Patients with >or=1 claim containing a diagnosis of nephritis during the preindex period were identified. Health care resource utilization and direct medical care cost data were assessed over a period of 12 months; paid amounts were used as a proxy for costs and were expressed in year-2008 US dollars.

RESULTS: A total of 15,590 patients with SLE were identified (13,828 women, 1762 men; mean age, 48 years); 1068 (6.9%) had a history of nephritis. The mean age of patients with SLE without nephritis was significantly greater compared with the group with nephritis (47.9 vs 46.5 years, respectively; P < 0.001), and a greater proportion of this group were women (89.0% vs 84.7%; P < 0.001). Over a period of 12 months, 30.3% of patients with nephritis were hospitalized compared with 13.6% of those without nephritis (P < 0.001); the mean lengths of hospital stays were 16.52 and 9.69 days (P < 0.001) in patients with and without nephritis, respectively. Patients with nephritis also underwent more outpatient laboratory tests (mean, 64.42 vs 30.96; P < 0.001) and had a significantly higher mean number of intravenous infusions (mean, 1.7 vs 1.1; P < 0.001), and total 12-month follow-up costs were significantly greater in patients with nephritis compared with those without nephritis (mean, $30,652 vs $12,029; P < 0.001). Costs associated with inpatient and outpatient care were 252% and 146% higher in patients with SLE with nephritis, respectively. Outpatient costs were associated with approximately half of the total costs in patients with or without nephritis; pharmacy costs accounted for 20% of the total costs in patients with SLE and nephritis and 27% of total costs among those without nephritis. Significantly higher costs also were found in patients with nephritis when only SLE-related costs were assessed and after differences in patient characteristics and comorbidities were adjusted through multivariate analyses (all, P < 0.05).

CONCLUSIONS: The present data analysis found that patients with SLE with nephritis consumed significantly more health care resources, with >2.5-fold the costs, compared with those without nephritis. The majority (84%) of added costs were attributable to inpatient hospitalizations and outpatient services, and 16% were attributable to pharmacy services.