The Swedish version of the Sheehan Disability Scale - a valid and brief measure of functioning

Rationale, aims and objective: The Sheehan Disability Scale (SDS) is a brief instrument used to measure functional disability, but the Swedish translation has not been psychometrically evaluated. The aim of this paper is to test the psychometric properties of the Swedish translation and to further examine concurrent and external validity.Method: In this cross-sectional study, 160 young psychiatric patients from an open care unit in Sweden, were recruited based on a clinical diagnosis of Attention Deficit Hyperactivity Disorder (ADHD), Bipolar Disorder (BD) and/or Borderline Personality Disorder (BPD) and re-diagnosed for confirmation. Participants were interviewed concerning socio-demographic data and a socio-demographic index (SDI) was constructed. Reliability of SDS was measured as internal consistency and an exploratory factor analysis was performed. Level of functioning was measured by SDS scores and Global Assessment of Functioning (GAF). SDS, both self-assessed and expert rated and GAF scores were compared to measure concurrent validity, while SDS and the SDI were compared to measure external validity.Results: The Swedish SDS had a Cronbach’s alpha coefficient of 0.77. An exploratory factor analysis showed that the SDS-items loaded on a single factor with an eigenvalue of 2.06. Self-assessed SDS-scores correlated with expert rated GAF-scores (r = -0.606) and, to some extent, with SDI scores (r = 0.280). Patients with an SDI score ≥ 1 had higher SDS-scores (t=2.70, p=0.008).Conclusions: The Swedish SDS has similar psychometric properties as the English and Spanish versions. It showed both concurrent and external validity, but external validity was weake