Validation of Boolean 2.0 criteria for remission and quality of life prediction in Korean patients with rheumatoid arthritis receiving targeted therapy

Abstract

Objective To validate the revised patient global assessment (PtGA) threshold of 2 cm in the Boolean 2.0 remission definition by assessing its agreement with index-based remission criteria and its predictive validity for quality of life (QoL) outcomes, compared with Boolean 1.0, in Korean patients with rheumatoid arthritis (RA) receiving targeted therapy.Methods Data from a multicentre prospective cohort of patients with RA initiating treatment with Janus kinase inhibitors or biologic disease-modifying anti-rheumatic drugs were analysed. Remission was assessed using Boolean 1.0, Boolean 2.0, and index-based criteria including DAS in 28 joints calculated with ESR (DAS28-ESR), Clinical Disease Activity Index (CDAI), and Simplified Disease Activity Index (SDAI). Agreement between Boolean definitions and index-based criteria was evaluated using Cohen's kappa. Predictive validity was determined by comparing remission status at week 24 and patient-reported outcomes at week 48, specifically HAQ-Disability Index (HAQ-DI) <= 0.5 and EuroQoL-5 Dimension (EQ-5D) = 1.Results Among 506 enrolled patients, 414 completed the 48-week follow-up. Boolean 2.0 showed stronger agreement with DAS28-ESR remission than Boolean 1.0 (kappa = 0.50 vs. 0.39), but weaker agreement with CDAI (kappa = 0.75 vs. 0.48) and SDAI (kappa = 0.76 vs. 0.64). Boolean 1.0 demonstrated higher positive predictive values for HAQ-DI <= 0.5 (0.90 vs. 0.82) and EQ-5D = 1 (0.38 vs. 0.30) compared with Boolean 2.0.Conclusion Although Boolean 2.0 improves concordance with DAS28-ESR, it does not enhance the prediction of long-term functional or QoL outcomes. Its broader definition of remission warrants cautious interpretation in clinical practice.