Dactylitis predicts more severe joint damage, higher disease activity in axPsA

The presence of dactylitis in patients with axial psoriatic arthritis (axPsA) may result in higher disease activity and more severe joint damage compared to those without, reports a study.

A total of 186 patients with axPsA who met the Classification Criteria for Psoriatic Arthritis were included in the analysis. The authors compared clinical data, radiographic changes, and disease activity in those with or without dactylitis using t tests, Mann-Whitney U tests, or Kruskal-Wallis tests for continuous variables. They used chi-square or Fisher exact tests for categorical values.

Finally, the association between dactylitis and damage detected by radiography was evaluated in logistic regression analysis.

Patients with dactylitis had higher C-reactive protein (p=0.004), erythrocyte sedimentation rate (p=0.006), neutrophil-to-lymphocyte ratio (p=0.04), and platelet-to-lymphocyte ratio (p=0.02) than those without. Dactylitic axPsA patients also had higher tender joint counts, swollen joint counts, Disease Activity Index for Psoriatic Arthritis scores, and Health Assessment Questionnaire scores (p<0.001).

Likewise, axPSA patients who had dactylitis achieved higher values for the Disease Activity Score in 28 joints, Ankylosing Spondylitis Disease Activity Score, Bath Ankylosing Spondylitis Functional Index, and Bath Ankylosing Spondylitis Disease Activity Index (p<0.05) than those who did not.

However, fewer dactylitic axPsA patients met the criteria for minimal and low disease activity (p<0.05). They also showed more severe damage as seen in radiography (p<0.05), higher sacroiliac scores (odds ratio [OR], 2.08, 95 percent confidence interval [CI], 1.14‒3.79; p=0.02), and greater reduction in bone mass density (OR, 2.42, 95 percent CI, 1.34‒4.37; p=0.003).

No significant between-group differences were seen in HLA-B27 and the Leeds Enthesitis Index. Of note, only half of dactylitic axPsA patients experienced inflammatory back pain.

“Careful examination and proper management of axial involvement are recommended,” the authors said.