title: An improved algorithm for activated protein C resistance and factor V Leiden screening.
abstract: OBJECTIVE
  To evaluate the performance of a Russell viper venom-based activated protein C resistance (APCR) screening test relative to DNA analysis for the factor V Leiden mutation.
  
  
  METHODS
  We evaluated the concordance between Pefakit APCR screening results and DNA analysis for 435 patients homozygous (n = 11), heterozygous (n = 310), or wild-type (n =114) for the G1691A allele.
  
  
  RESULTS
  Using receiver operating characteristic analysis, we found that a cutoff of 1.89 for the APCR ratio yields a sensitivity and specificity of 99.1%. In patients with discrepant genotype-phenotype correlation, their APCR may provide a more clinically relevant result.
  
  
  CONCLUSIONS
  We compared several strategies for employing reflex testing and found that performing initial APCR screening followed by confirmatory molecular analysis on a subset of cases in the borderline regions between the diagnostic groups can reduce unnecessary testing by approximately 80% without compromising diagnostic accuracy.
authors: Department of Pathology, Brigham and Women's Hospital, 75 Francis St, Boston, MA 02115, USA.
authors: Adrianna Z
authors: AZ
authors: Herskovits
authors: Elizabeth A
authors: EA
authors: Morgan
authors: Susan J
authors: SJ
authors: Lemire
authors: Neal I
authors: NI
authors: Lindeman
authors: David M
authors: DM
authors: Dorfman
mesh_terms: D020016:Activated Protein C Resistance / Q000097:blood / Q000175:diagnosis* / Q000235:genetics; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D005165:Factor V / Q000235:genetics*; D005260:Female; D056726:Genetic Association Studies; D005820:Genetic Testing / Q000379:methods*; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity
chemical_list: C095381:factor V Leiden; D005165:Factor V
keywords: Activated protein C resistance; Factor V Leiden; Screening assays; Venous thromboembolism