The norwegian version of the psoriasis disability index--a validation and reliability study.
OBJECTIVE
The aim of this study was to translate the Psoriasis Disability Index (PDI) into Norwegian and validate it in a Norwegian setting. The PDI is a measure that was developed to assess the impact of psoriasis on the patient's life.


METHODS
Two hundred and eighty-two patients with psoriasis were included in the study (80% outpatients, and 20% hospitalized).


RESULTS
Face and content validity were assessed as satisfactory. The PDI seems to capture issues of importance to patients. The results indicate that the PDI does not capture a unidimensional concept. A factor analysis (principal component with orthogonal rotation) resulted in three factors (physical, social, and hygienic) that were substantially different. All three factors had satisfactory internal consistency. Altogether they explained 58% of the variance. In addition, there were differing patterns of correlations with external criteria, such as dimensions of SF-36, as well as with sex, age, and education.


CONCLUSIONS
The PDI has been found to have acceptable reliability in this study. However, further validation is necessary to estimate the sensitivity to change.
Wahl
A K
AK
Department of Public Health and Primary Health Care, University of Bergen, Norway. astrid.klopstad.wahl@hibu.no
Wiklund
I
I
Moum
T
T
Hanestad
B R
BR