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

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