title: Sensitivity, specificity and predictive value of modified assays for activated protein C resistance in children.
abstract: Very little data is available assessing the clinical utility of coagulation-based APC resistance assays compared to DNA-based analysis for the factor V Leiden mutation in children. Therefore, the clinical utility of four aPTT-based assays for APC resistance was evaluated in 169 children, ages 3 months through 16 years. The prevalence of the Arg506 to Gln mutation was 7/169 (4.1%). Using cutoff points derived from the normal PCR-screened population (n = 162), two assays for APC resistance (APC-SR and n-APC-SR) gave poor concordance with the PCR assay (sensitivity 29% and 57%, respectively). Two modified assays (FDAPC-SR and n-FDAPC-SR), in which patient plasma was prediluted 1:5 in factor V deficient plasma, gave excellent concordance (sensitivity 100%). The predictive value of a positive test was 0.25, 0.44, 1.00 and 0.88 for the APC-SR, n-APC-SR, FDAPC-SR and n-FDAPC-SR, respectively. The FDAPC-SR and n-FDAPC-SR tests gave excellent discrimination using cutoff values derived from the total population (n = 169) without regard to previous PCR screening results.
authors.affiliation: The Division of Hematology/Oncology, S. Illinois University School of Medicine, Springfield, USA.
authors.forename: G
authors.initials: G
authors.lastname: Brandt
authors.forename: R
authors.initials: R
authors.lastname: Gruppo
authors.forename: C J
authors.initials: CJ
authors.lastname: Glueck
authors.forename: D
authors.initials: D
authors.lastname: Stroop
authors.forename: A
authors.initials: A
authors.lastname: Becker
authors.forename: A
authors.initials: A
authors.lastname: Pillow
authors.forename: P
authors.initials: P
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D001780:Blood Coagulation Tests; D002648:Child; D002675:Child, Preschool; D004351:Drug Resistance; D006801:Humans; D007223:Infant; D011237:Predictive Value of Tests; D011486:Protein C / Q000494:pharmacology*; D012680:Sensitivity and Specificity
chemical_list: D011486:Protein C