NEW research has revealed that pain persists in >50% of rheumatoid arthritis (RA) patients treated with methotrexate for 3 months, even in those who demonstrated a ‘good clinical response’.
The research, led by Dr Jon Lampa, Karolinska Institute, Stockholm, Sweden, undertook a population-based study using a cohort of 1,241 patients enrolled on the Swedish Rheumatology Quality register between 1996 and 2010, more than two-thirds of whom were women. The median age of the subjects was 56 years, and all were taking methotrexate as their only disease-modifying drug, though possibly in combination with prednisone or nonsteroidal anti-inflammatory drugs. At baseline, measurements of Disease Activity Score in 28 Joints (DAS28), C-reactive protein, disability level (as on the Health Assessment Questionnaire [HAQ]), erythrocyte sedimentation rate (ESR), and pain on a visual analogue scale were taken.
At 3 months the response to treatment was measured by the change in DAS28 score, and patients were categorised into three groups: patients who showed a good response (GR) (40%), those who showed a moderate responders (MR) (38%), and those with no response (NR) (23%). There were patients who had continuing pain at 3 months within each of these groups: 29% of patients with GR, 70% with MR, and 83% with NR.
The results suggest that increasing age, higher HAQ scores, and lower ESR at baseline are associated with persistent pain, and could be potential predictors for clinical use. The researchers concluded that: “these results are in line with the hypothesis that a subgroup of early RA patients exhibit pain that is not inflammatory mediated and where non-RA causes and alternative treatment strategies need to be considered.”
The authors also found that the subjective findings of tender joints and patient global assessment (PGA) were less severe in those patients with persistent pain; this supports their conclusion and helps to rule out fibromyalgia and widespread pain as causes. Furthermore, almost 1 in 5 patients reported a worsening of pain, even amongst the GR group; the main factors associated with worsening were lower HAQ score, fewer tender and swollen joints, worse DAS28 score and PGA, and current smoking status.
These results could provide information on how care of RA patients who may be in pain despite treatment can be improved. More research is required to uncover the effect of anxiety and depression on pain outcomes.