Psoriatic arthritis, rheumatoid arthritis causes a similar damage to the hands, but also psoriasis

Both PSA and RA have well-documented impacts on patients’ physical functioning, but less has been published about how the loss of hand function experienced by patients with RA compares to that of other diseases, according to Anna-Maria Liphardt, PhD of the Friedrich-Alexander Erlangen University of Nuremberg and of the Erlangen University Clinic in Germany and colleagues.

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

Therefore, Liphardt and colleagues decided to comprehensively assess hand function in PsA and RA side by side, analyzing objective strength measures and also patients’ perceptions of hand function. In addition to comparing these measures in the two categories of diseases, the authors also compared them with healthy controls.

In the study, 299 subjects were enrolled, divided almost equally between patients with RA (101 patients), patients with PSA (92 patients) and non-arrhythmic controls (106 patients). The nonarthritic patient’s arm consisted of 51 patients with psoriasis and 55 healthy controls.

Patients were evaluated using a number of measures. A hand dynamometer was used to measure the isometric adhesion 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 objects from a table into a box. with his eyes open. Finally, patients were asked to assess their own hand function using the Michigan Hand Questionnaire (MHQ). Data were taken for both hands, but investigators noticed which hand was the patient’s dominant hand.

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

We found that the impact of the disease on hand function is particularly pronounced in older subjects, suggesting that younger people are better at functionally compensating for their diseases, they said. This can be caused by better muscle performance and neuromuscular interaction in younger people, but also by the management of RA and PSA in the last two decades.

However, the authors also reported something they did not expect: patients with psoriasis were experiencing significant changes in hand function.

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

Liphardt and colleagues said the finding suggests that patients with psoriasis “have a functional arthritis-like phenotype.”

Such observations support concepts that patients with psoriasis have an altered response to stress not only on the skin but also on the musculoskeletal structures, they said.

Investigators added that functional changes in patients with psoriasis may indicate a more pronounced progression of PsA, but said the question should be investigated with further studies.

Reference

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

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