Heparin and warfarin anticoagulation intensity as predictors of recurrence after deep vein thrombosis or pulmonary embolism: a population-based cohort study
Key result
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 180-day VTE recurrence.
Why the study?
Does the intensity of heparin and warfarin anticoagulation predict 180-day VTE recurrence in patients with incident VTE?
Population
1,166 residents of Olmsted County, MN with incident venous thromboembolism over the 14-year period of…
Comparison
Heparin (target APTT ≥ 0.2 anti-X U/mL) and… vs Lower proportions of time in the therapeutic…
Design
Cohort
Follow-up
180 days
Authors
Discussion
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Member takes
Implication
Supports monitoring anticoagulation intensity in VTE; leaves open whether randomized trials confirm causality and guide practice.
Key Points
- To evaluate whether recommended anticoagulation intensity thresholds for heparin and warfarin predict 180-day venous thromboembolism recurrence.
- Identified and followed an inception cohort of 1,166 residents with incident venous thromboembolism over a 14-year period (1984–1997) for 180-day recurrence.
- Evaluated activated partial thromboplastin time (APTT), international normalized ratio (INR), and other clinical variables using multivariable Cox proportional hazards modeling.
- Overall, 1,026 patients (88%) received heparin, 989 (85%) received warfarin, and 85 patients (8%) developed recurrent venous thromboembolism.
- Increasing proportion of time with an APTT ≥ 0.2 anti-Xa U/mL on heparin and an INR ≥ 2.0 on warfarin were independently associated with significant reductions in recurrence, while active cancer significantly increased recurrence risk.
- Time to heparin initiation, duration of overlapping heparin and warfarin therapy, and inferior vena cava filter placement were not independent predictors of recurrence.
Study Design
Type
Cohort (n=1,166)
Multicenter
No
Structured PICO
Does the intensity of heparin and warfarin anticoagulation predict 180-day VTE recurrence in patients with incident VTE?
P
Population
1,166 residents of Olmsted County, MN with incident venous thromboembolism (deep vein thrombosis or pulmonary embolism) over the 14-year period of 1984-1997.
I
Intervention
Heparin (target APTT ≥ 0.2 anti-X(a) U/mL) and warfarin (target INR ≥ 2.0) anticoagulation.
C
Comparator
Lower proportions of time in the therapeutic anticoagulation range (lower intensity anticoagulation).
O
Outcome
180-day venous thromboembolism (VTE) recurrence.hard clinical
Maintaining adequate anticoagulation intensity with heparin (APTT ≥ 0.2 anti-X(a) U/mL) and warfarin (INR ≥ 2.0) significantly reduces the risk of 180-day VTE recurrence.
Cite This Study
Heit et al. (2011) conducted a cohort in Incident venous thromboembolism (deep vein thrombosis or pulmonary embolism) (n=1,166). Heparin and warfarin anticoagulation was evaluated on 180-day venous thromboembolism (VTE) recurrence. 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 180-day VTE recurrence.