AMSTERDAM – Pain continues to affect almost one in five people 1 year after a diagnosis of rheumatoid arthritis, according to data from a large prospective study reported at the European Congress of Rheumatology.

At enrollment, 64% of patients still had remaining pain, and at 1 year, 24% had remaining pain, according to data from the Canadian Early Arthritis Cohort (CATCH).

Although the percentage of patients with widespread pain also decreased, it still affected some 5% of patients, down from 9% at baseline, the principal investigator of CATCH, Vivian P. Bykerk, MD, said.

Dr. Bykerk of the University of Toronto and the Hospital for Special Surgery, New York, presented the research on behalf of Yvonne C. Lee, MD, of Northwestern University, Chicago, and noted that they had previously published data showing the incidence of widespread pain was highest within the first year of an RA diagnosis and then plateaued (Ann Rheum Dis. 2013;72[6];949-54). This plateau could have been related to the control of inflammation, Dr. Bykerk observed.

“We think the first 12 months are really a critical window during which time acute inflammatory pain may transition, if you will, to chronic noninflammatory pain,” Dr. Bykerk said.

The aim of their current study was to look at the evolution of pain in the year following an RA diagnosis and to see whether there were any predictive factors for remaining pain and widespread pain. The latter might previously have been described as fibromyalgia, Dr. Bykerk said, and was defined as a difference between the tender and swollen 28-joint counts of at least seven points. Remaining pain was defined as a score of more than 4 on a pain intensity numerical rating scale.

Data on 1,270 patients who were enrolled in CATCH across 17 sites in Canada during 2007-2017 were used. The majority of the sample was female (73%) and white (82%) and had been experiencing symptoms for a median of 6 months. The mean age of patients was 54 years.

At enrollment, patients had a mean number of two comorbidities, with up to 12% having another condition that might contribute to pain, such as osteoarthritis (12%), a back or spinal problem (10%), or fibromyalgia (9%).

Most (72%) patients were being treated with methotrexate initially, either alone (29%) or in combination with other drugs, and almost two-thirds were using steroids, either orally (29%) or parenterally (32%). A small percentage (2%) were treated with biologics, but this is unusual until almost 12 months, Dr. Bykerk observed.

The baseline predictors for remaining pain at 1 year were high baseline pain (odds ratio, 2.1), sleep difficulties (OR, 2.2), and disability measured by the Health Assessment Questionnaire Disability Index (OR, 1.5). The latter was the strongest predictor for lingering widespread pain. The number of comorbidities were also predictive of lingering pain, though this was not a significant difference.

Assessing and considering treatment for these predictors may be important for improving persisting pain, Dr. Bykerk suggested. “In future we’d like to validate our findings with other validated questionnaires; we have a depression questionnaire now being used in the study, and we want to understand what subgroups of patients have different trajectories of pain.”

CATCH is currently funded via unrestricted research grants from Amgen, Pfizer, Bristol-Myers Squibb, Medexus, Eli Lilly, Merck, and Sandoz Canada Pharmaceuticals. Dr. Bykerk had no personal financial disclosures.

SOURCE: Lee YC et al. EULAR 2018 Congress.Abstract OP0349.

Pain remains after rheumatoid arthritis diagnosis