한양대학교 류마티즘연구원

Objectives: This study aims to determine the independent impact of definitions of remission/low disease activity (LDA) on direct/indirect costs (DCs, ICs) in a multicentre inception cohort.

Methods: Patients from 31 centres in 10 countries were enrolled within 15 months of diagnosis and assessed annually. Five mutually exclusive disease activity states (DAS) were defined as (1) remission off-treatment: clinical (c) SLEDAI-2K=0, without prednisone/immunosuppressants; (2) remission on-treatment: cSLEDAI-2K=0, prednisone ≤5 mg/day and/or maintenance immunosuppressants; (3) LDA-Toronto Cohort (TC): cSLEDAI-2K≤2, without prednisone/immunosuppressants; (4) modified lupus LDA state (mLLDAS): SLEDAI-2K≤4, no activity in major organs/systems, no new activity, prednisone ≤7.5 mg/day and/or maintenance immunosuppressants and (5) active: all remaining assessments.At each assessment, patients were stratified into the most stringent DAS fulfilled and the proportion of time in a DAS since cohort entry was determined. Annual DCs/ICs (2021 Canadian dollars) were based on healthcare use and lost workforce/non-workforce productivity over the preceding year.The association between the proportion of time in a DAS and annual DC/IC was examined through multivariable random-effects linear regressions.

Results: 1692 patients were followed a mean of 9.7 years; 49.0% of assessments were active. Remission/LDA (per 25% increase in time in a remission/LDA state vs active) were associated with lower annual DC/IC: remission off-treatment (DC -$C1372; IC -$C2507), remission on-treatment (DC -$C973; IC -$C2604,) LDA-TC (DC -$C1158) and mLLDAS (DC -$C1040). There were no cost differences between remission/LDA states.

Conclusions: Our data suggest that systemic lupus erythematosus patients who achieve remission, both off and on-therapy, and reductions in disease activity incur lower costs than those experiencing persistent disease activity.