Widespread, Extra-Articular Pain Common in Patients With Psoriatic Arthritis

Widespread and extra-articular pain are common in patients with psoriatic arthritis (PsA) and may have a significant effect on key clinical outcomes, according to study results published in The Journal of Rheumatology.

Limited data exist on the topography of pain and the clinical relevance of pain areas in patients with PsA. The objective of the current study was to determine pain locations in patients with PsA compared with those with fibromyalgia, and to explore the association between pain areas and disease activity, treatment target, joint function, and effect of disease.

The current case control study included patients with PsA and control participants with fibromyalgia. All participants were asked to complete a body chart during the intake interview to determine their pain in the previous week in 80 body locations. Areas with a clear presence of tender and/swollen joints or enthesitis were excluded from the analysis to ensure the presence of pain not due to synovitis/enthesitis process. Researchers used the Widespread Pain Index (WPI) to determine the extent of bodily pain in 19 different body regions of all study participants. They also conducted assessments of disease activity, treatment target, function, and effect of disease in patients with PsA.

A total of 50 patients (33 men; mean age, 56.7 years) with PsA and 50 control participants (3 men; mean age, 58.4 years) with fibromyalgia were included in the study. The most common pain locations in patients with PsA were at the levels of the hands, knees, and feet, but pain was also present in other extra-articular areas. Although pain locations were similar among both study groups, patients with fibromyalgia had a greater frequency of pain. Compared with patients with PsA, those with fibromyalgia had a higher number of pain areas on body charts (median, 3 vs 8.5, respectively; P <.001) and WPI scores (median, 3 vs 7, respectively; P <.001).

In patients with PsA, there was a correlation between the number of painful areas, assessed using body chart or WPI score, and disease activity, function, and effect of disease (P <.01). The median number of pain areas was significantly lower among patients in remission compared with those with low, moderate, or high disease activity. The number of extra-articular pain areas was high among patients with moderate or high disease activity, and among those with a greater effect of disease or reduced function.

Researchers acknowledged several study limitations, including the potential bias linked to sex differences and the lack of assessment of the potential effect of comorbidities on pain perception.

“The present study could contribute to an important aspect of this multifaceted disease, such as the assessment of widespread pain in a more detailed fashion,” the researchers concluded.

Reference

Lubrano E, Scriffignano S, Morelli R, Perrotta FM. Assessment of widespread and extra-articular pain in psoriatic arthritis: a case-control study. J Rheumatol. Published online January 15, 2021. doi:10.3899/jrheum.201163