Psoriatic arthritis and rheumatoid arthritis cause similar hand disorders, but so does psoriasis

PsA and RA have well-documented impacts on the physical functioning of patients, but less has been published on how the loss of hand function experienced by RA patients compares to that of others. diseases, according to Anna-Maria Liphardt, PhD, from Friedrich-Alexander Erlangen University Nürnberg and University Clinic Erlangen, Germany, and colleagues.

“The impact of inflammatory arthritis on hand function has been studied primarily in RA,” they said, “and studies comparing hand function in these diseases are rare.”

Liphardt and his colleagues therefore decided to comprehensively assess hand function in PSA and RA side-by-side, examining objective force measurements and also patients’ perceptions of hand function. In addition to comparing these measurements in the 2 disease categories, the authors also compared them to healthy controls.

In the study, 299 subjects were recruited, divided roughly evenly between patients with RA (101 patients), patients with RP (92 patients) and non-arthritic controls (106 patients). The non-arthritis patient arm consisted of 51 psoriasis patients and 55 healthy controls.

The patients were assessed using a number of measures. A hand dynamometer was used to measure isometric grip strength. The Moberg-Picking-Up (MPUT) test was used to assess fine motor skills, and patients were also timed to see how long it took them to move 12 small items from a table to a box with their eyes open. . Finally, patients were asked to assess their own hand function using the Michigan Hand Questionnaire (MHQ). The data was taken for both hands, but the researchers noted which hand was a patient’s dominant hand.

The researchers found that gender, age, disease group, and hand dominance all affected hand function. However, PsA and RA appeared to have similar influences on hand function, and in both cases the impact was greater for women than for men.

“We have found that the impact of disease on hand function is particularly pronounced in older subjects, suggesting that younger individuals are better able to functionally compensate for their diseases,” they said. “This may be caused by generally better muscle performance and neuromuscular interaction in younger individuals, but also by the disease management of RA and PsA over the past two decades.”

However, the authors also reported something they did not expect: Patients with psoriasis exhibited significantly impaired hand function.

“Although these patients showed no clinical signs of PSA, the hand function was clearly impaired and mirrored that of patients with RA and PSA, but not in healthy controls,” they said.

Liphardt and his colleagues said the finding suggests that patients with psoriasis “exhibit a functional phenotype similar to arthritis.”

“Such observations support the concepts that patients with psoriasis exhibit an altered stress response not only in the skin but also in musculoskeletal structures,” they said.

Investigators added that it’s possible that functional changes in patients with psoriasis could be a sign of more pronounced PSA progression, but said the issue should be investigated with other studies.

Reference

Liphardt AM, Manger E, Liehr S, et al. Similar impact of psoriatic arthritis and rheumatoid arthritis on objective and subjective parameters of hand function. ACR Open Rheumatol. 2020; 2 (12): 734-740. doi: 10.1002 / acr2.11196

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