title: Factor structure, internal consistency and construct validity of the Sheehan Disability Scale in a Spanish primary care sample.
abstract: OBJECTIVE
  The Sheehan Disability Scale (SDS) is a three-item instrument that measures disability in three inter-related domains: work, family life/home responsibilities and social/leisure activities. The main objective of the present study was to examine the factor structure, reliability and construct validity of the SDS in a wide Spanish sample of primary care (PC) patients.
  
  
  METHODS
  One phase cross-sectional survey. A total of 3815 patients, aged 18 years or older attending PC for a medical visit, were interviewed between October 2005 and March 2006. The interviews included the Structured Clinical Interview for DSM-IV Axis I Disorders for depressive and anxiety disorders, the Mini-International Neuropsychiatric Interview for the rest of mental disorders, a medical conditions checklist, the 2.0 version of the 12-item Short-Form Health Survey (SF-12) for measuring quality of life and the SDS.
  
  
  RESULTS
  The principal component analysis and the subsequent confirmatory factor analysis indicated that the SDS is one-dimensional (normed fit index = 0.990, non-normed fit index = 0.987, comparative fit index = 0.991, goodness-of-fit index = 0.993, standardized root mean-square residual = 0.037, root mean-square error of approximation = 0.053). The internal consistency of the scale was good (α = 0.83) and it was significantly associated with the physical and mental component of the SF-12. Concerning discriminative validity, patients with major depression or panic disorder scored higher on the SDS than patients with chronic medical conditions or with no chronic pathology. We also found that a cut-off point of 8 in the SDS adequately discriminated between patients with and without depression (area under the curve = 0.814, sensitivity = 81.60%, specificity = 70.60%).
  
  
  CONCLUSIONS
  The SDS seems a reliable, valid and useful clinical tool for measuring disability in Spanish PC patients.
authors.affiliation: Parc Sanitari Sant Joan de Déu, Mental, Fundación Sant Joan de Déu, Sant Boi de Llobregat, Barcelona, Spain. jvluciano@sjd-ssm.com
authors.forename: Juan V
authors.initials: JV
authors.lastname: Luciano
authors.forename: Jordan
authors.initials: J
authors.lastname: Bertsch
authors.forename: Luis
authors.initials: L
authors.lastname: Salvador-Carulla
authors.forename: José M
authors.initials: JM
authors.lastname: Tomás
authors.forename: Ana
authors.initials: A
authors.lastname: Fernández
authors.forename: Alejandra
authors.initials: A
authors.lastname: Pinto-Meza
authors.forename: Josep M
authors.initials: JM
authors.lastname: Haro
authors.forename: Diego J
authors.initials: DJ
authors.lastname: Palao
authors.forename: Antoni
authors.initials: A
authors.lastname: Serrano-Blanco
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011320:Primary Health Care; D013030:Spain; D011795:Surveys and Questionnaires / Q000592:standards*; D055815:Young Adult