Heparin and warfarin anticoagulation intensity as predictors of recurrence after deep vein thrombosis or pulmonary embolism: a population-based cohort study.

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Heparin and warfarin anticoagulation intensity as predictors of recurrence after deep vein thrombosis or pulmonary embolism: a population-based cohort study.

Blood. 2011 Sep 2;

Authors: Heit JA, Lahr BD, Petterson TM, Bailey KR, Ashrani AA, Melton LJ

Abstract
To test recommended anticoagulation measures as predictors of 180-day VTE recurrence, we identified all Olmsted County, MN residents with incident VTE over the 14-year period, 1984-1997, and followed each case (n=1166) forward in time for VTE recurrence. We tested the activated partial thromboplastin time (APTT), international normalized ratio (INR) and other measures of heparin and warfarin anticoagulation as predictors of VTE recurrence while controlling for baseline and time-dependent characteristics using Cox proportional hazards modeling. Overall, 1026 (88%) and 989 (85%) received heparin and warfarin, respectively, and 85 (8%) developed VTE recurrence. In multivariate analyses, increasing proportions of time on heparin with an APTT?0.2 anti-X(a) U/mL and on warfarin with an INR?2.0 were associated with significant reductions in VTE recurrence, while the hazard with active cancer was significantly increased. Time from VTE onset to heparin start, duration of overlapping heparin and warfarin, and inferior vena cava (IVC) filter placement were not independent predictors of recurrence. At a heparin dose ?30,000 U/day, the median proportion of time with an APTT?0.2 anti-X(a) U/mL was 92%, suggesting that routine APTT monitoring and heparin dose adjustment may be unnecessary. In summary, lower intensity heparin and standard intensity warfarin anticoagulation are effective in preventing VTE recurrence.

PMID: 21890644 [PubMed - as supplied by publisher]

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