Validity and responsiveness of the Osnabruck Hand Eczema Severity Index (OHSI): a methodological study

Abstract

The Osnabruck Hand Eczema Severity Index (OHSI) is a scoring system for the assessment of the severity of hand eczema (HE). To assess the clinimetric value of the OHSI and to validate the longitudinal responsiveness of the OHSI using the Manuscore as a gold standard. OHSI and Manuscore scores were compared before and after 3 weeks' inpatient treatment of 62 patients with occupational HE. Correlation coefficients and 95% limits of agreement were calculated and the ability of OHSI to identify severe HE was analysed. The responsiveness of the OHSI in monitoring skin changes over time was evaluated by calculating effect sizes. High correlation was found between the OHSI and Manuscore at both scoring occasions (around r(s) = 0.77). Differences between both measurements were within the 95% limits of agreement for 94% of patients, with a tendency for the OHSI to underestimate the severity at very low and at very high values compared with the Manuscore. Responsiveness to change was good. Both instruments showed significant improvement between the scoring occasions. Using the OHSI values, the proportion of classification to the correct tertile of score change was 69%. Effect size from untreated to treated was 0.6 for the Manuscore and 1.1 for the OHSI, with higher effect sizes in individuals with severe HE. Even though the OHSI allows less differentiation than the Manuscore, it shows adequate validity and responsiveness to change. Thus the OHSI is suitable for both monitoring the severity of HE and the effects of treatment.