Long-Term Pain Predicted at 3 Month Follow-Up in Patients With RA

Patients with rheumatoid arthritis (RA) experience unacceptable pain up to 2 years after diagnosis, according to results from a study published in Rheumatology.

Researchers recruited patients from 2012 to 2016 and included 275 patients with early RA in this analysis. They used the visual analogue scale (VAS; 0-100 mm) to assess pain. Unacceptable pain was defined as a VAS rating greater than 40 mm. Low inflammation was defined as a C-reactive protein level less than 10 mg/L.

Using logistic regression analysis, researchers assessed the factors that could predict unacceptable pain at baseline and after 3 months.

The average level of pain reported by participants decreased significantly by an average of 23.5 points (95% CI, 18.3-28.8) during the initial 3 months; however, there was no significant change in pain levels for the rest of the follow-up period. Moreover, the proportion of patients who experienced unacceptable pain levels increased from 5% at the start of the study to 14% after 2 years.

After 2 years, 32% of patients experienced pain that was deemed unacceptable and 81% of these patients had low levels of inflammation. Results also revealed that patient-reported outcome factors such as pain scores, patient global assessment, and joint tenderness were predictors of unacceptable pain at the 1 and 2-year marks. These factors were identified 3 months after the study began but not at the beginning of the study. Objective inflammatory measures did not show any significant associations with pain.

Among several limitations, the study included a small sample size due to missing data. In addition, selection bias was reported for patients with more severe disease. Finally, there was no standardized protocol for joint assessments, and different physicians examined the patients during follow-up visits, as is standard clinical practice.

The study authors concluded, “Our results indicate that patients with worse [patient-reported outcomes] at the 3-month follow-up have increased risk of long-lasting pain. Furthermore, extensive joint tenderness may also be useful for predicting long-term pain despite low inflammation. The association between patient reported outcomes and future pain, as well as the lack of association with objective inflammatory measures, are also compatible with an important role for a non-inflammatory pain spectrum in RA.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, or device companies. Please see the original reference for a full list of disclosures.