Background Pain in patients with rheumatoid arthritis (RA) is the most common and troublesome symptom, occurs frequently in many sites in the muscular-skeletal system, causes fatigue and functional impairment. The origin of pain in RA may be inflammatory and/or other, such as increased sensitivity to pain, fibromyalgia and osteoarthritis.

Objectives To study unacceptable pain in an inception cohort of patients with RA at 15 years follow-up

Methods This study concerns 477 patients from the BARFOT inception cohort study, consisting of 839 patients with early RA, who have passed the pre-defined 15 year follow-up visit. Unacceptable pain (UP) was defined as ≥40 mm on a continuous VAS pain scale of 100 mm with the ends “no pain” and “worst possible pain” (1). ADL- function was assessed by the HAQ test, physical function by the SOFI test and joint damage by the van der Heijde modified Sharp method. Remission was defined as DAS28 ≤2.6.

The prevalence of UP over time as well as the relationship of UP with clinical variables were assessed. Baseline predictors of UP after 15 years were evaluated by logistic regression.

Results The mean baseline VAS pain was 45 mm, decreased after 6 months to 29 and remained after that fairly stable through the years ending in 31 at 15 years. UP followed a similar course with 56% of the patients at baseline, which decreased to 30% after 6 months and then behaved stable until 15 years, 34%. Seventy-seven per cent of the patients with UP were not in remission at 15 years, while 23% had UP in spite of being in remission.

Patients with UP who were in remission at the 15 years visit had higher mean age (p=0.004), ESR (p=0.001) and SOFI (p=0.001) than patients without UP.

Patients with UP who were not in remission at this point in time were more often women (0.008) and had more tender joints (p=0.001) than patients who did not have UP.

In both remission groups the mean DAS28, patient global assessment and HAQ were higher in patients with UP compared with patients without.

The means of the x-ray joint damage scores - total score, erosion and joint space narrowing scores - were very similar among patients with or without UP, statistically not significant.

A logistic regression analysis of the ability of baseline variables to predict UP at 15 years was performed. It was shown that female gender and baseline pain independently predicted unacceptable pain at 15 years in patients not in remission while in patients in remission high age and ESR were independent predictors.

Conclusions Pain is a frequent and relentless suffering during the long-term course of rheumatoid arthritis. In this study, 34% of the patients had unacceptable pain 15 years after diagnosis indicating unsatisfactory treatment. Unacceptable pain also occurred in patients in remission indicating that pain in RA is multifactorial. Therefore, the cause of pain should be identified and treatment initiated accordingly.

References

1. Altawil, R. Pain mechanisms of fatigue and autonomic function in rheumatoid arthritis [dissertation]. Stockholm: Karolinska Institutet; 2016.

References

Disclosure of Interest None declared