title: A new method for assessing how sensitivity and specificity of linkage studies affects estimation.
abstract: BACKGROUND
  While the importance of record linkage is widely recognised, few studies have attempted to quantify how linkage errors may have impacted on their own findings and outcomes. Even where authors of linkage studies have attempted to estimate sensitivity and specificity based on subjects with known status, the effects of false negatives and positives on event rates and estimates of effect are not often described.
  
  
  METHODS
  We present quantification of the effect of sensitivity and specificity of the linkage process on event rates and incidence, as well as the resultant effect on relative risks. Formulae to estimate the true number of events and estimated relative risk adjusted for given linkage sensitivity and specificity are then derived and applied to data from a prisoner mortality study. The implications of false positive and false negative matches are also discussed.
  
  
  CONCLUSIONS
  Comparisons of the effect of sensitivity and specificity on incidence and relative risks indicate that it is more important for linkages to be highly specific than sensitive, particularly if true incidence rates are low. We would recommend that, where possible, some quantitative estimates of the sensitivity and specificity of the linkage process be performed, allowing the effect of these quantities on observed results to be assessed.
authors: The Kirby Institute, UNSW Australia, Sydney, New South Wales, Australia.
authors: Cecilia L
authors: CL
authors: Moore
authors: The Kirby Institute, UNSW Australia, Sydney, New South Wales, Australia.
authors: Janaki
authors: J
authors: Amin
authors: School of Public Health & Community Medicine, UNSW Australia, Sydney, New South Wales, Australia.
authors: Heather F
authors: HF
authors: Gidding
authors: The Kirby Institute, UNSW Australia, Sydney, New South Wales, Australia.
authors: Matthew G
authors: MG
authors: Law
mesh_terms: D000465:Algorithms; D006801:Humans; D008498:Medical Record Linkage / Q000379:methods / Q000592:standards*; D016347:Medical Records Systems, Computerized / Q000592:standards* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D018511:Systems Integration