Association between quantitative APA assay results and recurrent VTE after stopping anticoagulant therapy. Results of APA assays in individual patients according to whether they did or did not have recurrent VTE during follow-up after stopping anticoagulant therapy. The cutoff values used to define whether a result was within the normal range are shown for each type of APA assay. When an APA was measured on 2 occasions in the same patient, the higher of the 2 values was used in these figures. The median values in patients with and without recurrent VTE are shown; the P values (2-sided median test) associated with each of these differences were: ACA IgG, P = .15; ACA IgM, P = .041; anti-β2GP1, P = .70; LA APTT, P = .17; and LA dilute Russell viper venom time (DRVVT), P = .70. GPL, IgG phospholipid units; MPL, IgM phospholipid units.