Residual disease activity in rheumatoid arthritis patients treated with subcutaneous biologic drugs that achieved remission or low disease activity: a longitudinal observational study

The aim of this study was to evaluate the residual disease activity (RDA) and function in rheumatoid arthritis (RA) patients treated with subcutaneous biologic drugs that achieved a status of remission and low disease activity (LDA) according to the various indices validated for RA and to explore the factors associated with RDA. We consecutively enrolled RA patients that started a new subcutaneous biologic treatment. At baseline and after 3 and 6 months of treatment, we assessed the rate of patients that achieved remission or LDA using the Disease Activity Score on 28 joints, Clinical Disease Activity Index, Simplified Disease Activity Index, and American College of Rheumatology/European League Against Rheumatism remission criteria. The presence of RDA was evaluated as the rate of patients with at least tender joint count > 1, swollen joint count > 1, pain on VAS > 10 mm, general health (VAS) > 10, patient's disease activity (VAS) > 10, physician disease activity (VAS) > 10, and C reactive protein > 1 mg/dl. We also evaluated the impaired function defined as HAQ score > 0.5. Factors associated to RDA were also investigated. Ninety-three adult patients with RA were enrolled. At 6 months, RDA occurred mostly at the level of Patient's reported outcome items and less frequently in tender and swollen joints and acute-phase reactants. Interestingly, about one fourth of patients in LDA and up to one fifth of patients in remission had residual functional impairment with an HAQ score greater than 0.5. RDA in RA was present even in patients with remission or LDA, especially for the patient's reported outcome. Impaired function was also present in a significantly rate of patients.