Remission in rheumatoid arthritis: benefit over low disease activity in patient reported outcomes and costs
Arthritis Research & Therapy 2014, 16:R56 doi:10.1186/ar4491Published: 21 February 2014
Rheumatoid arthritis (RA) is a chronic inflammatory disease that causes a considerable burden for the patient and society. It is not clear yet whether aiming for remission (REM) is worthwhile, especially when compared to low disease activity (LDA).
In 356 consecutive RA patients, we obtained data on physical function (health assessment questionnaire (HAQ)), health related quality of life (HRQoL: Short Form 36 (SF36), Short Form 6 dimensions (SF-6D), Euro Qol 5D (EQ-5D)), work productivity (work productivity and activity impairment questionnaire (WPAI)), as well as estimation of direct and indirect costs. Cross-sectionally, data were compared in patients within different levels of disease activity according to simplified disease activity index (SDAI; remission (REM <=3.3); n = 87; low disease activity (LDA: 3.3 < SDAI <=11); n = 103; moderate to high disease activity (MDA/HDA) >11 n = 119) using analyses of variance (ANOVA). Longitudinal investigations assessed patients who changed from LDA to REM and vice versa.
We found differences in patients achieving REM compared to LDA for HAQ (0.39 +/- 0.58 versus 0.72 +/- 68), WPAI (percent impairment while working 11.8 +/- 18.7% versus 26.8 +/- 23.9%; percent of overall activity impairment 10.8 +/- 14.1% versus 29.0 +/- 23.6%)), EQ-5D (0.89 +/- 0.12 versus 0.78 +/- 0.6) and SF-36 (physical component score (PCS): 46.0 +/- 8.6 versus 38.3 +/- 10.5; mental component score (MCS): 49.9 +/- 11.1 versus 47.9 +/- 12.3) (P <0.01 for all, except for SF36 MCS). Regarding costs we found significant differences of direct and indirect costs (P <0.05) within different levels of disease activity, with higher costs in patients with higher states of disease activity. Longitudinal evaluations confirmed the main analyses.
Patient within REM show better function, HRQoL and productivity, even when compared to another good state, namely LDA. Also from a cost perspective REM appears superior to all other states.