Characterizing Nonarticular Pain at Early Rheumatoid Arthritis Diagnosis: Evolution Over the First Year of Treatment and Impact on Remission in a Prospective Real-World Early Rheumatoid Arthritis Cohort

Abstract

Objective: Our objective was to characterize nonarticular pain (NAP) at early rheumatoid arthritis (RA) diagnosis, the evolution over the first year of treatment, associations with active RA inflammation, and the impact on remission.

Methods: This real-world, longitudinal multicenter cohort study observed participants with active early RA (symptoms <1 year and Clinical Disease Activity Index [CDAI] >2.8) enrolled between January 2017 and January 2022 who completed a body pain diagram over 1 year. Participants were grouped by prespecified definitions of NAP: (1) none, (2) regional, or (3) widespread. Rheumatologists performed joint counts. Descriptive statistics summarized the frequency and evolution of NAP patterns over 1 year. Chi-square tests compared the proportions of tender and/or swollen joints by the presence of pain in each NAP section. Multiadjusted generalized estimating equations regression models estimated associations of NAP patterns with remission outcomes.

Results: Participants (N = 392) were 70% female, with a mean ± SD age of 56 ± 14 years and mean ± SD symptoms duration of 5.1 ± 2.7 months. More than half reported NAP at baseline, with most (73%) presenting with regional NAP. Common patterns of regional NAP were axial (40%) and pain in upper quadrants (17%). A total of 43% of those with regional NAP persisted or worsened over 1 year, whereas 73% of those with widespread NAP resolved or improved. Joint inflammation was more frequently reported in areas with NAP versus areas without NAP. Regional and widespread NAP were associated with lower odds of reaching CDAI remission (adjusted odds ratio 0.42, 95% confidence interval 0.26-0.70 and adjusted odds ratio 0.30, 95% confidence interval 0.12-0.74), respectively.

Conclusion: Regional NAP is common and persistent in early RA and impacts remission. RA activity may contribute to NAP. More attention to NAP in RA care is warranted.

Figure 1

Classification of NAP according to patient‐reported BPD. Each numbered area checked by the patient on BPD corresponds to an area listed under each section. Because it is not possible to have all five sections, the maximum number of sections is four. The criteria for NAP are (1) no sections if it is no NAP, (2) one to three sections if it is regional NAP (three sections if limited to one half of body [upper half or lower half or right half or left half]), and (3) three to four sections if it is widespread NAP (three sections if bilateral plus above and below the waist). *If it is neck‐ or back‐only areas, use the axial section, and if it is neck or back plus another area in the quadrant use the quadrant section. BPD, body pain diagram; NAP, nonarticular pain.

Figure 2

Point prevalence of regional and widespread nonarticular pain over 1‐year follow‐up in the early rheumatoid arthritis cohort. There were 392 patients at baseline, 343 at 6 months, and 305 at 12 months.

Figure 3

Evolution of NAP patterns during the first year following early rheumatoid arthritis diagnosis (N = 392). *Percentages in oval shapes are calculated from the entire sample (N = 392). ^∆Percentages in boxes are calculated from the denominators indicated in the oval shapes. Red shading indicates the presence of prevalent, incident, recurring, or persistent NAP or the evolution of regional to widespread NAP. Green shading indicates the absence or resolution of NAP or the evolution of widespread to regional NAP. NAP, nonarticular pain.

Figure 4

Frequency of active rheumatoid arthritis joints in corresponding areas of NAP compared to no NAP in early rheumatoid arthritis. ^∆ Shaded areas on the body pain diagram are illustrative examples; all views are anterior except the axial (adapted from Margolis et al). The joint homunculus was adapted from an image in the University of Alberta's Disease Activity Score Calculator (https://www.epicore.ualberta.ca/demo/joints). *Joints assessed for tenderness and/or swelling within each NAP section; the frequency of active joints in each section for patients with NAP and those without NAP is indicated in red. ^ɸThese P values compare the frequency of active joints in each section for patients with NAP and those without NAP; a chi‐square test was used for categorical variables. NAP, nonarticular pain.