A longitudinal analysis of costs associated with change in disease activity in systemic lupus erythematosus

Abstract

Objectives:To estimate the economic consequences of changes in disease activity on healthcare resource utilization (HRU) and costs.Methods:A retrospective longitudinal study of systemic lupus erythematosus (SLE) patients receiving care in a regional integrated health delivery system in the US from 01/2004 through 03/2011 was conducted using electronic health records, medical chart reviews, and claims. Eligible patients were ≥18 years old, with ≥1 rheumatologist-confirmed SLE diagnosis and ≥1 eligible rheumatology encounter. Patients were continuously enrolled ≥90 days before and ≥30 days after the encounters. Charts were manually reviewed to estimate SLEDAI scores. Average unit costs of each medical procedure, facility use, and prescription were estimated from a payer perspective (2011 USD) using a managed care claims database. HRU and costs were calculated for the 30-day period surrounding every SLEDAI score date (10 days before and 19 after). Relationships between HRU/costs and SLEDAI scores were estimated using mixed-effect models.Results:Overall, 178 SLE patients were included; mean age was 50.6 years, 91% were female, and 95.5% Caucasian. Patients had a total of 1343 encounters with SLEDAI scores over an average period of 1035 days. Reductions of SLEDAI scores were associated with reductions in HRU and costs. SLEDAI score reductions of 4-points were associated with reductions of 10% HRU and 14% costs over a 30-day period; reductions of 8-points had associated reductions of 19% HRU and 26% costs; and reductions of 10-points had associated reductions of 23% HRU and 31% costs. Annualized, changes in SLEDAI scores are associated with changes of $2485 (SLEDAI score change: 10–6), $4624 (10–2), and $5579 (10–0), respectively.Conclusion:Reductions in disease activity were associated with substantial reductions of HRU and costs.Limitations:Only short-term effects of disease activity change were investigated, disregarding other potential benefits of low disease activity on long-term organ damage prevention or comorbidities.