The Work and Social Adjustment Scale as a Measure of Dysfunction in Chronic Insomnia: Reliability and Validity

Abstract

Dysfunction is an integral part of chronic insomnia. Despite this, very little effort has yet been made to design and psychometrically validate an insomnia-specific measure of dysfunction. The purpose was to examine the psychometric properties of the Work and Social Adjustment Scale (WSAS) as a measure of dysfunction in chronic insomnia. Seventy-three patients with chronic insomnia from three subsamples participated. All the patients completed the WSAS, the Insomnia Severity Index (ISI), and sleep diaries over one week. An exploratory factor analysis suggested a one-factor solution for the WSAS, determining dysfunction, accounting for 73.7% of the variance. The internal consistency of the WSAS was α = .91. The test-retest reliability for the WSAS items was high at .90-.99 and for the entire scale .99. A cut-off at 17 points was established, discriminating those with subclinical versus moderate or severe clinical insomnia (88% sensitivity and 78% specificity). Evidence of convergent and criterion validity was documented via (1) a significant, positive association between the WSAS and ISI and (2) a higher WSAS score among those with severe clinical insomnia, relative to those with moderate clinical and subthreshold insomnia, as well as a higher WSAS score among those with moderate clinical insomnia relative to those with subthreshold insomnia. The WSAS was also shown to be a treatment-sensitive measure for insomnia patients. The WSAS appears as a reliable and valid measure of dysfunction in chronic insomnia. Additional advantages are its shortness, easiness, and treatment-sensitivity.