Background Although treatment with methotrexate is efficient in decreasing inflammation and joint destruction in RA, several patients report remaining pain at follow-up, and the potential discrepancy between decrease in inflammation and pain needs to be explored further.
Objectives We investigated the frequency and possible predictors of remaining pain after 3 months treatment with MTX as the only DMARD treatment in early RA, with special focus on the patients who had a good clinical response to MTX.
Methods The study base was cases reported to the Environmental investigation of RA (EIRA) cohort 1996-2009 who had follow-up data in the Swedish Rheumatology Quality Register (1996-2010), a total of 1241 patients (69% women). Disease activity was measured with the 28-joint based disease activity score (DAS28) and the EULAR response criteria were used to evaluate clinical response to treatment. The primary endpoint was ‘remaining pain’ at the 3 months follow-up visit, defined as pain according to a 100 mm visual analog scale above 20 mm (VAS pain >20 mm), which has earlier been stated as a cutoff for patient reported significant pain (Ref Wolfe J Rheumatol 2007). The association between baseline parameters and remaining pain was evaluated by logistic regression and expressed as odds ratios (OR) with 95% confidence interval (95%CI), adjusted for age at onset/treatment start, gender and cigarette smoking status.
Results Median VAS-pain was 54 mm at baseline and 25 mm at the 3 months follow-up visit. Remaining pain was observed in 57% of all patients at the 3 months follow-up. The frequency of EULAR good/moderate/no response was 40%/38%/22% respectively, and in these response groups, the frequency of remaining pain was 29%/70%/83% respectively. In the EULAR good responder group (n=421), remaining pain was associated with more disability, measured as higher baseline HAQ (adjusted OR 2.2, 95%CI=1.4-3.4 per unit increase) and less inflammation, measured as lower baseline erythrocyte sedimentation rate, ESR (adjusted OR 0.81; 95%CI=0.70-0.93 per 10 mm increase). In line with this, patients who were EULAR good responders and had a remaining pain at follow-up exhibited lower ESR (p<0.02), and higher HAQ (p<0.02) at baseline compared to patients with less pain. Moreover, increase in VAS pain during the treatment period was observed in 19% of the whole cohort and frequencies of increased pain in the response groups were 9%/15%/45% respectively
Conclusions Majority of early RA patients starting methotrexate monotherapy at diagnosis have remaining pain after 3 months. Further, almost 1/5 of the patients actually exhibit increase in VAS pain during treatment. Despite good response to methotrexate, almost a third of those patients have remaining pain, and in moderate responders, more than two thirds of the patients have remaining pain. Remaining pain despite a good response to MTX is associated with more disability and less inflammation at baseline. These results are in line with the hypothesis that a subgroup of early RA patients exhibit pain that is not inflammatory mediated and where alternative treatment strategies can be discussed.
References Wolfe J Rheumatol 2007
Disclosure of Interest None Declared