The SmithKline Beecham ‘quality of life’ scale: a validation and reliability study in patients with affective disorder

Abstract

The rationale for the development of a Repertory-Grid based quality of life assessment (QOL) is described. The emergent scale, the SmithKline Beecham Quality of Life Scale (SBQOL) utilizes 23 predetermined constructs and three fixed elements: self now, ideal self and sick self. Inclusion of the latter two elements provides a personal frame of reference for the individual and recognizes the highly idiosyncratic and subjective nature of the experience which constitutes quality of life. A study of the validity and reliability of the SBQOL was conducted in 129 patients presenting to their GP with either major depression or generalized anxiety disorder, as defined by DSM III R. Patients were treated at the discretion of their GP and followed over a period of 12 weeks with assessments of treatment efficacy being performed at 6 weeks and 12 weeks in parallel with administration of the SBQOL. The results from co-administration of standard efficacy measures such as the Hamilton Depression Rating Scale (HAMD) and Hamilton Anxiety Scale (HAMA) with the SBQOL, provided good evidence of construct validity. Evidence in support of the concurrent validity of the SBQOL was provided by co-administration of the Sickness Impact Profile and General Health Questionnaire (external criteria) with the SBQOL scale. Test-retest reliability and internal consistency were high. No obvious advantage was conferred by the use of principal components analysis from the Flexigrid software package in contrast to a simple arithmetical procedure for computing interelement distances. It is concluded that the SBQOL provides a valid, reliable and practicable approach to the assessment of quality of life in patients with affective disorder.