title: Search for secondary osteoporosis: are Z scores useful predictors?
abstract: OBJECTIVE
  To determine whether Z scores can be used to predict the likelihood of patients having a secondary cause of low bone mineral density.
  
  
  METHODS
  A retrospective cross sectional study was conducted among 136 consecutive patients with osteoporosis at Ninewells Hospital, Dundee, UK, between 1998-2002.
  
  
  RESULTS
  20.5% of female patients in this study were identified with previously unrecognised contributors to the low bone mineral density. In women, at a Z score cut-off of -1, the sensitivity of detecting a secondary cause for osteoporosis is 87.5% with a positive predictive value of 29.2%.
  
  
  CONCLUSIONS
  In women, a Z score of -1 would identify a majority of patients with a secondary cause for low bone mineral density and identifies patients who would especially benefit from a thorough history and clinical examination.
authors.affiliation: Department of Endocrinology, Ninewells Hospital, Dundee, UK. krishnan.swaminathan@nhs.net
authors.forename: K
authors.initials: K
authors.lastname: Swaminathan
authors.forename: R
authors.initials: R
authors.lastname: Flynn
authors.forename: M
authors.initials: M
authors.lastname: Garton
authors.forename: C
authors.initials: C
authors.lastname: Paterson
authors.forename: G
authors.initials: G
authors.lastname: Leese
mesh_terms: D015519:Bone Density / Q000502:physiology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000209:etiology* / Q000503:physiopathology; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods; D012680:Sensitivity and Specificity