Both PsA and RA have a positive effect on patients’ physical activity, but there have been fewer publications related to how patients with RA lose hand function compared to other diseases, according to Anna-Maria Liphardt, PhD, of Friedrich-Alexander Erlangen Nürnberg University and the Clinic of the University of Erlangen, Germany, and colleagues.
“The impact of infectious arthritis on manual labor has been extensively studied in the UK,” they said, “and studies comparing manual labor in these diseases are scarce. ”
Liphardt and his colleagues therefore decided to conduct a comprehensive evaluation of manual labor in PsA and RA side by side, by looking at objective strength measures and also patients ’perceptions of manual labor. In addition to comparing these measures in the 2 disease categories, the authors compared healthy controls.
In the study, 299 subjects were enrolled, almost evenly divided between patients with RA (101 patients), patients with PsA (92 patients), and nonarthritic controls (106 patients). The nonarthritic patient’s arm consisted of 51 patients with psoriasis and 55 healthy controls.
Patients were assessed using a number of measures. A hand-held dynamometer was used to measure isometric grip strength. The Moberg Lifting Test (MPUT) was used to assess fine motor skills, and patients were also given time to see how long it took them to move 12 small objects from a table into a box with the their eyes opened. Finally, patients were asked to assess their own manual activity using the Michigan Hand Questionnaire (MHQ). Data were provided for both hands, but investigators noted which hand was the main hand of patients.
Researchers found that gender, age, disease group, and hand have been influenced by manual labor. However, there appeared to be a similar effect of PsA and RA on manual labor, and in each case the effect was greater for women than men.
“We found that the effect of disease on manual labor is particularly pronounced in older subjects, suggesting that younger people are better at actively compensating for their diseases,” they said. “This could be caused by improved muscle performance and neuromuscular interactions in younger people, but also by the management of RA and PsA disease in the last two decades.”
However, the authors also revealed something they did not expect: Patients with psoriasis experienced a significant change in manual labor.
“Although these patients did not show any clinical signs of PsA, manual labor was clearly impaired and was a mirror in patients with RA and PsA but not in healthy controls,” they said.
Liphardt and colleagues said the finding showed psoriasis patients “exhibit a phenotype-like action of arthritis.”
“Such observations bring back concepts that patients with psoriasis show an altered stress response not only in the skin but also in the muscular structures,” they said.
The researchers said it is possible that functional changes in patients with psoriasis could be a sign of more obvious progression to PsA, but said the issue needs to be explored with further studies.
Information
Liphardt AM, Manager E, Liehr S, et al. Similar effect of psoriatic arthritis and rheumatoid arthritis on objective and thematic parameters of manual function. ACR Open Rheumatol. 2020; 2 (12): 734-740. doi: 10.1002 / acr2.11196