Summary
Long-term therapy with low-molecular-weight heparin (LMWH) is the treatment of choice
for cancer patients with venous thromboembolism (VTE). However, the ideal doses of
LMWH have not been thoroughly studied. We used the RIETE Registry data to assess the
influence of the daily LMWH dosage on outcome during the first three months after
VTE. We used propensity score-matching to compare patients who received <150 vs. those
receiving ≥150 UI/kg/day LMWH. Up to July 2010, 3,222 cancer patients with VTE received
long-term therapy with fixed doses of LMWH. Of these, 1,472 (46%) received <150 IU/kg/day
(mean, 112 ± 28), and 1,750 received ≥150 IU/kg/day (mean, 184 ± 32). Results of the
propensity score matching involved 1269 matched pairs. During follow-up, the incidence
of pulmonary embolism (PE) recurrences was similar (1.2% vs. 1.9%), but patients receiving
<150 IU/kg/day LMWH had a lower incidence of fatal PE than those treated with ≥150
IU/kg/day (0.2% vs. 1.0%; p=0.004). Multivariate analysis confirmed that patients
receiving <150 IU/kg/day LMWH had a lower risk for fatal PE (odds ratio [OR]: 0.2;
95% confidence interval [CI]: 0.06–0.8) and for major bleeding (OR: 0.6; 95% CI: 0.3–1.0)
than those treated with ≥150 IU/kg/day. In real life, one in every two cancer patients
with VTE received lower doses of LMWH than those used in randomised trials, with large
variations from patient to patient. Unexpectedly, patients treated with <150 IU/kg/day
LMWH had fewer fatal PE cases and fewer major bleeding events than those receiving
≥150 IU/kg/day LMWH. This finding, however, should be validated in prospective clinical
trials.
Keywords
Cancer - heparins - venous thrombosis - pulmonary embolism