The Hairdex quality of life instrument-A translation and psychometric validation in patients with alopecia areata.

Background: The German Hairdex quality of life (QoL) instrument is specific to hair and scalp diseases, developed for self-rating and consists of 48 statements divided into five domains: Symptoms, Functioning, Emotions, Self-confidence and Stigmatisation. There was a need of a Swedish reliability tested, validated hair and scalp specific QoL instrument why the German Hairdex was chosen to be translated and reliability tested in a systematic way.

Objectives: To make a translation, a reliability test of stability, and validation of the German Hairdex QoL instrument among 100 Swedish patients with a dermatological ICD-10 diagnosis of alopecia areata (AA).

Methods: An eight-step method by Gudmundsson was used as a model with a forward and backward translation and with comments from an expert panel. A statistical test-retest (ICC (2,1)) analysis was made, followed by an internal consistency analysis. A comparison between the German and Swedish Hairdex-S constructs by a principal component analysis was performed.

Results: The Hairdex-S was very well accepted by patients. The ICC(2,1) test-retest showed a good to excellent correlation of 0.91 (CI [0.85-0.95]). Internal consistency was  = 0.92. Like the original Hairdex, Hairdex-S showed good factorability with a Kaiser-Meyer-Olkin measure of 0.82 and with one component explaining 70% of the variance: original Hairdex instrument (69%). When tested on patients with AA, the domains Functioning and Emotions had the strongest loadings, followed by Stigmatisation and Self-confidence. Younger AA patients at self-assessment and patients who reported to be younger at the onset of AA, scored statistically significantly higher on the Hairdex-S, indicating an overall lower QoL on domains Emotions and Functioning, respectively.

Conclusions: The Hairdex-S is very well accepted by AA patients, shows very good psychometric properties, and a very good agreement with the original Hairdex. The Swedish Hairdex instrument can be recommended for evaluation of patients QoL as well as for research purposes.