Abstract 1990
Background
Thromboprophylaxis with low molecular weight heparin (LMWH) is recommended in hospitalized cancer patients with reduced mobility and/or other risk factors for venous thromboembolism. An unresolved issue is whether the commonly used LMWH, enoxaparin should be given in a fixed dose for thromboprophylaxis or adjusted to weight. The aim of this study was to examine whether hospitalized cancer patients, treated with a fixed dose of enoxaparin (40 mg/day) reach appropriate target level of anti-Xa, and whether anti-Xa level in these patients is correlated to body size, gender, and blood creatinine level.
Methods
Between Oct 2015 to June 2017 hospitalized cancer patients with indication for thromboprophylaxis and without contraindication for SC enoxaparin (40 mg/day) were entered into the study. Prior to the initiation of enoxaparin, patients were weighed and measured and blood samples were collected for PT/PTT, CBC and Creatinine. Blood samples for peak anti Xa level were collected at 48-120 hrs post initiation of enoxaparin (3 hrs after injection). Target anti-Xa was defined as 0.2-0.5 U/ml.
Results
Eighty patients were enrolled (male/female: 46/34; age: 25-84, median 66yrs). 72 patients met inclusion criteria and had full data for analysis. The most common indication for prophylactic enoxaparin treatment was ECOG performance status 3-4 (82%). Median anti Xa level was 0.255 U/ml (range 0.01-0.77). Anti Xa levels were within target range in 40 patients (55.6%), below target in 26 patients (36.1%) and above target in 6 patients (8.3%). Anti Xa was higher in females (median 0.3 vs. 0.19 U/ml; p < 0.001) and correlated positively with serum creatinine (p = 0.003), and negatively with body weight (p < 0.001). Optimal threshold weight for predicting sub-therapeutic levels of anti Xa was identified at 78kg (sensitivity 43%, specificity 85%).
Conclusions
Using a policy of fixed dose enoxaparin resulted in under-treatment in more than one-third of a non-selective population of cancer patients, mainly in those whose weight was above 78kg. We suggest that prophylactic dosage of enoxaparin higher than 40 mg should be considered for patients with body weight above 80 kg.
Clinical trial identification
Legal entity responsible for the study
Helsinki committee Rambam Health Care Campus.
Funding
Has not received any funding.
Editorial Acknowledgement
Disclosure
B. Brenner: Honoraria for lectures and advisory board contributions: Pfizer, Leo Pharma, Sanofi, Rovi Laboratories, Bayer Pharmaceuticals. All other authors have declared no conflicts of interest.