Comparison of the Objective Severity and the Esthetic Perception of Nail Symptoms in Psoriasis

Abstract

Introduction: Nail changes are frequent in psoriasis, and the negative impact of nail psoriasis on patients' quality of life is well known. No data are available however about the association of the objective severity of nail psoriasis and the subjective perception of these symptoms. The purpose of this study was to determine the correlation between the severity of psoriatic nail changes (as determined by the Nail Psoriasis Severity Index [NAPSI]) and the esthetic assessment of nail psoriasis.

Methods: Participants (general population and psoriasis patients) were asked to rate 19 nail images (including psoriatic and healthy nails) on a 0-10 scale, based on how disturbing they considered them esthetically. Objective severity (NAPSI) scores of nails were compared to the subjective evaluation values.

Results: Nail symptom severity correlated well with the subjective scores. However, while nails with low (0) and high (6-8) NAPSI values received consistent subjective scores, the esthetic perception of nails with moderate NAPSI scores was rather heterogeneous. The age of the respondents showed robust positive correlation with the subjective assessment of nail symptoms both within the psoriatic and the general population.

Discussion: Gender, the presence of psoriasis, or medical education had no significant influence on the esthetic assessment of psoriatic nail changes.

Keywords: Nail Psoriasis Severity Index; Nail psoriasis; Subjective assessment of nail psoriasis.

Fig. 1

Subjective scoring (scale 0–10) of individual nail images. Boxplot center lines indicate the median value. X-axis numbering indicates the objective NAPSI score of respective nail images. Considerable subjective scoring heterogeneity within NAPSI categories 2, 4, and 5 indicate pronounced differences between objective and subjective scores.

Fig. 2

Linear regression of the mean subjective scoring of 19 nail images and participant age within psoriatic patients (a) and the general population (b). Each dot represents the score of a respondent. Dots may be slightly jittered to avoid overlaps. Age shows robust positive correlation with the subjective assessment of nail symptoms in both populations. Solid lines: line of best fit. Shaded area: 95% confidence interval.

Fig. 3

Comparison of average subjective scores of the 19 nails between different subpopulations. Boxplot of average scoring between the general population and psoriasis patients (PSO), displaying insignificant difference (a). A trend of higher scores are seen among psoriasis patients with more severe disease as compared to the general population (b) and mild psoriasis patients (c); however, the differences are not significant. Psoriatic patients with nail symptoms also show somewhat higher but not significantly different scores as compared to psoriasis patients without nail symptoms (d).

Fig. 4

a Linear regression analysis of subjective nail scoring versus respondent age between sexes in the complete study cohort. As a general trend, females (red dots and red confidence interval shading, solid best fit line) show higher scoring as a function of increasing age than males (blue dots and blue confidence interval shading, dotted best fit line). b Boxplot of differences between medical students and participants from the general population aged<30 years. Despite controlling for age bias, medical students show a trend of lower severity scoring.