The Norwegian version of the Quality of Life Scale (QOLS-N). A validation and reliability study in patients suffering from psoriasis

The aim of this study was to adapt, validate, and test for reliability the Quality of Life Scale in Norwegian (QOLS-N) for patients suffering from psoriasis. Two hundred and eighty-two patients with psoriasis were included in the study. Self-reported health was measured using the SF-36. Disease severity was also measured in 95 patients using the Psoriasis Area and Severity Index (PASI). The reliability of the QOLS-N was computed using the internal consistency reliability (Cronbach's alpha) and the test-retest reliability test. Face and content validity and construct discriminant ability of the QOLS-N were assessed. The results indicated that the QOLS-N has highly satisfactory rates of test-retest reliability (r = 0.83) and internal consistency reliability (alpha 0.86). As expected, the QOLS-N had a lower correlation with physical health (r = 0.24, p < 0.000) and self-reported symptoms (r = -0.20, p < 0.001), and a higher correlation with mental health (r = 0.52, p < 0.000). The correlation with disease severity was not significant (-0.06). The results reported in the present paper are in accordance with those derived in other validation studies. The QOLS-N seems to be a reliable and valid measure of global quality of life in patients suffering from psoriasis.