The Reliability of Disease Activity Score in 28 Joints–C-Reactive Protein Might Be Overestimated in a Subgroup of Rheumatoid Arthritis Patients, When the Score Is Solely Based on Subjective Parameters: A Cross-sectional, Exploratory Study

BACKGROUND: Disease Activity Score in 28 Joints (DAS28) is a scoring system to evaluate disease activity and treatment response in rheumatoid arthritis (RA). A DAS28 score of greater than 3.2 is a well-described limit for treatment intensification; however, the reliability of DAS28 might be overestimated. OBJECTIVE: The aim of this study was to evaluate the reliability of DAS28 in RA, especially focusing on a subgroup of patients with a DAS28 score of greater than 3.2. METHODS: Data from RA patients registered in the local part of Danish DANBIO Registry were collected in May 2015. Patients were categorized into 2 groups: First, those with DAS28 >3.2 with at least one swollen joint (SJ) or elevated C-reactive protein (CRP) (“objective group”), and second, patients with a DAS28 >3.2 who had no SJ, and CRP values were within the reference range (“subjective group”). Disease Activity Score in 28 Joints, Clinical Disease Activity Index, and Health Assessment Questionnaire scores were calculated for each group. We defined new score, DAS28 subjective, to focus on subjective parameters. RESULTS: Two hundred thirty patients were included; 198 (86.1%) and 32 (13.9%) patients were in the objective and subjective groups, respectively. Patients in the subjective group had lower mean values of DAS28 (P < 0.001) and Evaluator Global Assessment (P < 0.001) with less common immunoglobulin M rheumatoid factor (P < 0.001) and anti–cyclic citrullinated peptide positivity (P = 0.02) and contrarily higher mean values of tender joints (P = 0.04) and DAS28 based on subjective parameters (P = 0.003) compared with the objective group. CONCLUSIONS: Rheumatoid arthritis scoring systems should be used cautiously in patients who are considered for treatment intensification. Patients with central sensitization and psychological problems and those with false-positive diagnosis of RA are at high risk of overtreatment.