Risk of venous thromboembolism in cancer patients treated with epoetins or blood transfusions

Aims: Anaemia is common in cancer patients, with treatments including epoetins and blood transfusions. Although an increased risk of venous thromboembolism (VTE) has been associated with both therapeutics, studies comparing the risk of VTE between epoetins and transfusions in cancer patients are lacking.

Methods: A nested case-control study investigated this risk using the German Pharmacoepidemiological Research Database. Cohort members were incident cancer patients receiving first time treatment with epoetin or transfusion. A subcohort including only patients receiving chemotherapy was created, since the formally approved indication of epoetins is chemotherapy-induced anaemia. Cases were defined as patients developing VTE. For each case up to 10 gender- and age-matched controls were selected from the cohort. Multiple confounder adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for VTE and recent treatment with epoetins or transfusions (last 28 days before index date) compared with past anti-anaemic treatment were calculated by conditional logistic regression.

Results: Among 69 888 patients receiving first time treatment with epoetin or transfusion, 3316 VTE cases were identified. The aOR for VTE was 1.31 (95% CI 1.03, 1.65) for epoetins, 2.33 (95% CI 2.03, 2.66) for transfusions, and 2.24 (95% CI 1.34, 3.77) for epoetins and transfusions. Sensitivity analyses with a stricter VTE definition or an expanded time window yielded similar results. In the chemotherapy only subcohort the risk difference between epoetins and transfusions could not be verified (aOR 1.48, 95% CI 1.10, 1.98 vs. aOR 1.80, 95% CI 1.49, 2.19). Our study confirmed known VTE risk factors including previous VTE (aOR 14.76, 95% CI 12.79, 17.03) or surgery (aOR 1.83, 95% CI 1.67, 2.01). Epoetin-associated risk decreased after a safety warning by the European Medicines Agency setting maximum haemoglobin target values to 12 g dl(-1) .

Conclusions: Transfusions could be associated with a higher VTE risk than epoetins in cancer patients. Moreover, current prescribing patterns may have decreased the VTE risk for epoetins.