Adaptation of the Psoriatic Arthritis Quality of Life (PsAQoL) instrument for Sweden

Abstract

Objective: The Psoriatic Arthritis Quality of Life (PsAQoL) questionnaire is the first disease-specific patient-derived instrument for assessing QoL in patients with PsA and has been extensively validated in this population. The aim of the adaptation process reported here was to develop a Swedish version of the PsAQoL that was equivalent to, and met the same psychometric and acceptability standards as, the original instrument, which was developed in the UK.

Method:Translation of the original questionnaire into Swedish was performed by a professional and a lay panel. Field testing for face and content validity was performed by interviewing 13 patients. Finally, 123 patients with PsA were included in a test–retest postal survey designed to test reproducibility and construct validity. The PsAQoL was administered on two occasions approximately 2 weeks apart. The Nottingham Health Profile (NHP) was used as a comparator instrument.

Results: The Swedish version of the PsAQoL questionnaire showed good reliability at both time points and, as expected, correlated with the NHP. The scale was able to distinguish between groups based on self-reported general health and flare-up. Patients with active symptoms of both arthritis and psoriasis had worse QoL. The results also indicated that duration of disease has a progressive impact on PsAQoL scores.

Conclusions: This study provides evidence that the adapted PsAQoL can be used for clinical studies in Swedish patients. The instrument provides valuable information on the long-term effects of PsA on QoL.