Clinical symptoms of skin, nails, and joints manifest independently in patients with concomitant psoriasis and psoriatic arthritis

Abstract

This study correlated assessment tools for evaluating the severity of skin, nail, and joint symptoms in patients with psoriasis (Pso) and psoriatic arthritis (PsA). Adults with plaque Pso (with or without PsA) were enrolled from four U.S. institutions. Patients were evaluated using a novel 10-area Linear Psoriasis Area and Severity Index (XL-PASI), Psoriatic Arthritis Assessment (PsAA), Psoriatic Arthritis Screening and Evaluation Questionnaire (PASE), Nail Assessment (NA) and Joint Assessment (JA) tools, Psoriasis Weighted Extent and Severity Index (PWESI), and Lattice Physician Global Assessment (LS-PGA). Correlations between assessment tools and individual items in the assessment tools were performed. Data from 180 patients (55 with PsA) were analyzed. Highest correlations between tools (r = 0.77-0.88) were between the XL-PASI, PWESI and LS-PGA. Individual items in the XL-PASI correlated with items in the PWESI for extent skin symptoms, but not for all body areas. Overall, correlations were seen between hands and feet, between face and scalp, and between buttocks, chest, and back. Only low correlation was seen between items assessing joint symptoms with items assessing skin symptoms. These data support the notion that the complex phenotype of psoriatic disease requires instruments that assess the severity of skin, nails, and joints separately.

Figure 1. Correlations between tools scoring the severity of psoriasis and psoriatic arthritis and distribution of scores.

x-axis and y-axis values represent the respective scores of the tools. For comparison with traditional PASI scores, the XL-PASI scores are translated into estimated PASI scores. The dotted line with an estimated PASI score of 12 separates the patients with moderate and severe disease. r: Spearman correlation.

Figure 2. Correlations between individual items of psoriasis and psoriatic arthritis severity.

Each cell indicates the Spearman correlation between 2 of the 52 items. Cells with dark red indicates strong positive correlation, light red indicates weak positive correlation, dark green indicates strong negative correlation, and light green indicates weak negative correlation. Boxes in the upper left portion indicate correlations between affected nails and joints on hands and feet. Boxes in the lower right corner indicate “secondary structure” (within-box diagonal) between extent/involvement and severity/activity within regions. JA: Joint Assessment; NA: Nail Assessment; PASE: Psoriatic Arthritis Screening and Evaluation Questionnaire; PsAA: Psoriatic Arthritis Assessment; XL-PASI: Extended 10-area Linear Psoriasis Area and Severity Index; PWESI: Psoriasis Weighted Extent and Severity Index.