THE IMPACT OF DISEASE-ACTIVITY, TREATMENT AND DISEASE SEVERITY ON SHORT-TERM COSTS OF SYSTEMIC LUPUS-ERYTHEMATOSUS

Objective. To assess the impact of disease activity, current treatment , and global disease severity (or damage) on short term direct and ind irect costs of systemic lupus erythematosus (SLE). Methods. 150 patien ts were evaluated twice, one year apart. Disease activity was assessed by the SLE disease activity index, and ordinal scales were used to ev aluate treatment (prednisone = 0, 1 to 20 mg/day, > 20 mg/day, and use of immunosuppressive agents) and global disease severity [renal sever ity = 0 to 3, central nervous system (CNS) severity = 0 to 2, hematolo gic severity = 0 to 1]. Costs were assessed with the economic portion of the Health Assessment Questionnaire adapted for Canada. Results. Gl obal disease severity was significantly correlated with both direct (p = 0.0001) and indirect (p = 0.02) costs, and current treatment with i ndirect costs (p = 0.002). The renal and CNS subscales of the global s everity measure predicted direct costs (p < 0.01) and the CNS subscale predicted indirect costs (p = 0.002). Stepwise multivariable models s elected the global severity index (p = 0.004) as a predictor of direct costs, and either the treatment index (p = 0.02) or the global severi ty index (p = 0.02) as a predictor of indirect costs. Conclusion. The global disease severity index, particularly the subscales involving th e renal and CNS organ systems, and the treatment index are predictors of the short term costs of SLE.