Objective: The Diabetes Health Profile-18 (DHP-18) was developed to measure disease-specific health-related quality of life. It has been translated into Norwegian but remains invalidated. The purpose of this paper was to examine the psychometric properties of the Norwegian DHP-18.
Research design and methods: Participants with type 1 diabetes were recruited from three outpatient clinics in Norway. Clinical and sociodemographic data were collected, and participants completed the DHP-18 and the Short-Form 36 (SF-36). Descriptive analysis, frequencies, t-tests and the chi-squared tests were used. Principal axis factoring (PAF) and confirmatory factor analysis (CFA) were used. Convergent validity was tested using Spearman's correlation between the DHP-18 and SF-36. Reliability was tested using Cronbach's alpha and intraclass correlation coefficient.
Results: In total, 288 patients were included. No floor and ceiling effects were found. A forced PAF analysis revealed that three questions had an eigenvalue below 0.40. In the unforced PAF analysis, one question loaded below 0.40, while three questions loaded into a fourth factor. The correlation between the DHP-18 and SF-36 dimensions was low to moderate. Problematic internal consistency was observed for the disinhibited eating dimension in the forced PAF and in the suggested fourth dimension in the unforced PAF. CFA revealed poor fit. The test-retest reliability displayed good to excellent values, but responsiveness was limited.
Conclusions: Problematic issues were identified regarding factor structure, item loadings, internal consistency and responsiveness. Further evaluation of responsiveness is particularly recommended, and using a revised 14-item DHP version is suggested.
Keywords: quality of life; statistics/methodology; type 1; validation.