Validity and reliability testing of the Quality of Life Scale, Swedish version in women with fibromyalgia – statistical analyses

One consequence of constant widespread pain is a low quality of life. The purpose of the study was to examine whether the Quality of Life Scale, Swedish version (QOLS-S), regarded as a generic quality-of-life instrument, is a reliable and valid instrument for use in women with fibromyalgia (FM). Women with FM (n = 113) contributed data on the QOLS-S and other standardized instrument at three points in time. Internal consistency reliability estimates ranged from 0.89 to 0.92. Convergent construct validity was indicated by moderate agreement with a global life satisfaction question. Discriminant construct validity was denoted by low correlations with the physical functioning subscale of the SF-36. In a factor analysis three factors emerged: 'personal and social well-being', 'relations with others' and 'active participation'. A few of the items have high cross-loadings, and the instrument could be improved by rewording those items to more closely reflect one specific factor. Overall, these results provide evidence that the QOLS-S has acceptable validity and reliability for use in women with FM.