Evaluation of Skindex-16 construct validity in routinely collected psoriasis data: a retrospective analysis of the relationship between overall physician global assessment scores and Skindex-16 and measure discordance.

Patient-reported outcome measures (PROMs) capture disease severity metrics from the patient's perspective, including health-related quality of life (HRQL). Disease-specific validation of PROMs improves their clinical utility. We evaluated construct validity (HRQL) for Skindex-16 in routinely seen psoriasis patients and characterized instances of discordance between Skindex-16 scores and clinician-reported outcome measure of disease severity. We retrospectively studied psoriasis patients seen by University of Utah Dermatology from 2016 to 2020. Cross-sectional construct validity was assessed using quantile regression and Spearman correlation between overall physician global assessment (OPGA) score and Skindex-16 scores. Longitudinal within-subject correlation was performed using linear mixed models. Discordance (10th percentile or lower OPGA and 90th percentile or higher Skindex-16 score [clear skin, poor HRQL; cspHRQL] or the reverse [severe skin, good HRQL; ssgHRQL]) was characterized descriptively. 681 first-visit patients with psoriasis were included. Median overall Skindex-16 score varied by ≥ 10 points across all levels of OPGA scores. OPGA and Skindex-16 domain scores were moderately correlated (emotions ρ = 0.54, functioning ρ = 0.47, and symptoms ρ = 53). Longitudinal correlations were similar (emotion ρxy = 0.54, functioning ρxy = 0.65, symptoms ρxy = 0.47). Visits with cspHRQL discordance occurred for each Skindex-16 domain (emotions = 7, functioning = 13, symptoms = 12). The ssgHRQL group was observed within the emotions (n = 1) and functioning (n = 23) domains. Median Skindex-16 scores are different between different levels of OPGA and show moderate cross-sectional and longitudinal correlation. This supports construct validity in patients with psoriasis. Severe discordance was rare and most often for those with clear skin but poor HRQL. These discordances can prompt further patient-clinician conversation.

Lack of confidence interval reporting in dermatology: a call to action.

BACKGROUND: Confidence intervals (CIs) offer a complete and intuitive presentation of results and are more informative than P-values. The current prevalence of CI reporting in the dermatology literature has not been discussed. OBJECTIVES: To evaluate CI reporting prevalence in the dermatology literature, factors predicting reporting and to compare CI reporting in the dermatology literature with dermatology research in the New England Journal of Medicine (NEJM). METHODS: MEDLINE was queried for trials and observational studies published from 2007 to 2017 in six dermatology journals with varying impact factors: British Journal of Dermatology, Journal of Investigative Dermatology, JAMA Dermatology, Journal of the American Academy of Dermatology, European Journal of Dermatology and Journal of Cosmetic Dermatology. Randomly selected studies were reviewed to calculate CI reporting prevalence, and logistic regression identified factors predictive of CI reporting. RESULTS: Of 97 studies meeting the inclusion criteria, only 21 (22%; 95% CI 14-31%) reported CIs for the primary outcome. Of the remaining 76 studies, 43 reported a measure of variance (57%; 95% CI 45-67%). More recent year of publication was the strongest predictor for CI reporting [odds ratio 1·44; 95% CI 1·10-1·89 (P = 0·01)] in multivariable analysis. CI reporting in NEJM was significantly higher than in the dermatology literature (64% vs. 22%; P < 0·001). CONCLUSIONS: CI reporting in the dermatology literature is low. We urge both dermatology journals and researchers to improve clinical interpretation of study results by taking steps to increase CI reporting.