Remission and low disease activity are associated with lower healthcare costs: results from the Systemic Lupus International Collaborating Clinics (SLICC) inception cohort

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.