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Abstract
Background When initiating therapy with synthetic disease-modifying anti-rheumatic drugs (sDMARDs) in patients with rheumatoid arthritis (RA), the recommended target is remission or low disease activity (LDA). Limited data exist on the impacts of reaching remission rather than LDA on long-term outcomes.
Objectives To compare RA-patients who achieved Simplified Disease Activity Index (SDAI) remission versus LDA 6 months after initiating sDMARD therapy, with regard to physical function, Health Related Quality of Life (HRQoL) and disease activity during 5 years of follow-up in a routine clinical setting.
Methods Data were provided NOR-DMARD, a prospective multicentre longitudinal observational study. We selected DMARD-naïve patients with RA enrolled between December 2000 and April 2009 who had a registered visit with available SDAI status 6 months after initiating sDMARD therapy. Data on each patient were collected at baseline, after 3, 6 and 12 months, and yearly thereafter, including the modified Health Assessment Questionnaire (MHAQ), the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) with Physical and Mental Components Summary scores (PCS and MCS, respectively) and SF-6D, and assessments that allowed the calculation of the composite disease activity scores SDAI, Clinical Disease Activity Index (CDAI) and the Disease Activity Score based on 28 joint counts (DAS28). Multivariate linear mixed models were used to explore the effect of SDAI status at 6 months on physical function (MHAQ), HRQoL (SF-36 PCS and MCS, SF-6D) and disease activity (SDAI, CDAI, DAS28) during 5 year follow-up. The statistical models were adjusted for age, gender, disease duration and baseline disease activity. Furthermore, we performed mixed model analyses separately for patients in LDA, MDA and HDA at baseline, exploring the impact of SDAI status at 6 months on long-term disease activity in each sub-group.
Results Of 1148 eligible patients, 867 patients (75.5%) started with methotrexate in monotherapy and 281 (24.5%) started with another sDMARD or sDMARD combination. Patients in SDAI remission (n=145; 16.6%) rather than LDA (n=454; 39.5%) 6 months after initiating therapy had better physical function (MHAQ, estimated mean difference 0.11–0.20, p<0.02), higher SF-36 PCS (4.13–8.16, p<0.003) and SF-6D (0.06–0.12, p<0.0001), and lower disease activity (SDAI, 2.24–5.15, p<0.05) for all visits during 5 years of follow-up. Stratified mixed models analyses of patients in SDAI LDA, MDA and HDA at baseline, resulted in an overall significant long-term beneficial effect of achieving remission rather than LDA at 6 months; however, the differences were less distinct for patients who were already in a state of LDA at baseline.
Conclusions The achievement of SDAI remission 6 months after initiating DMARD-therapy was associated with favourable long-term outcomes compared with the achievement of SDAI low disease activity. The results from the study support that stringent remission is the optimal treatment target in patients with RA.
Disclosure of Interest V. Norvang: None declared, I. Olsen: None declared, E. Lie Consultant for: AbbVie, Celgene, Hospira, Pfizer, UCB, E. Kristianslund: None declared, T. Kvien Consultant for: AbbVie, Biogen, BMS, Boehringer, Ingelheim, Celltrion, Eli Lilly, Epirus, Janssen, Merck-Serono, MSD, Mundipharma, Novartis, Oktal, Orion Pharma, Hospira/Pfizer, Roche, Sandoz, UCB, E. Haavardsholm Grant/research support from: AbbVie, Pfizer, Roche, MSD, UCB, Consultant for: AbbVie, Pfizer, Roche, Eli Lilly, Celgene, UCB, T. Uhlig: None declared