Psychometric Properties of New Subscales of the Ostomy Adjustment Scale: A Cross-Sectional Study.

Background: The Ostomy Adjustment Scale (OAS), which consists of an overall sum score along with 34 single-item scores, has been frequently used to measure self-reported adjustment to life with an ostomy. However, it is unknown whether the OAS can be divided into meaningful thematic subscales that may make it easier to administer and to apply in a clinical feedback system.

Purpose: The purpose of this study was to specify thematic OAS subscales and evaluate their psychometric properties.

Patients and methods: A cross-sectional study was conducted with 302 patients across Norway having colostomy, ileostomy, or urostomy. The OAS items were divided into different subscales by expert nurses and patients based on clinical and theoretical considerations. The overall structural validity of this analysis of the OAS was examined using robust confirmatory factor analysis. We evaluated the overall goodness of fit using the root mean square error of approximation (RMSEA), the comparative fit index (CFI) and the Tucker-Lewis index (TLI). Factor loadings from the confirmatory factor analysis were used to calculate composite reliability values for the new OAS scales.

Results: The OAS was divided into seven subscales. The overall structure validity was acceptable with RMSEA = 0.053 (90% CI, 0.045-0.060), CFI = 0.913 and TLI = 0.904. The composite reliability values of all scales were >0.70.

Conclusions: The OAS can be divided into seven clinically meaningful subscales with acceptable psychometric properties.

Trial register: ClinicalTrials.gov Registration Number: NCT03841071. Date 18. February 2019 retrospectively registered.