Risk factors for incident venous thromboembolism in active cancer patients: A population based case-control study

Abstract

Background: Independent risk factors for cancer-associated incident venous thromboembolism (VTE) and their magnitude of risk are not fully characterized.

Aim: To identify non-cancer and cancer-specific risk factors for cancer-associated incident VTE.

Methods: In a population-based retrospective case-control study, we used Rochester Epidemiology Project and Mayo Clinic Cancer Registry resources to identify all Olmsted County, MN residents with active cancer-associated incident VTE, 1973-2000 (cases; n=570) and 1-3 residents with active cancer matched to each case on age, sex, date and duration of active cancer (controls; n=604). Using conditional logistic regression, we tested cancer and non-cancer characteristics for an association with VTE, including a cancer site VTE risk score.

Results: In the multivariable model, higher cancer site VTE risk score (OR=1.4 per 2-fold increase), cancer stage≥2 (OR=2.2), liver metastasis (OR=2.7), chemotherapy (OR=1.8) and progesterone use (OR=2.1) were independently associated with VTE, as were BMI<18.5kg/m(2) (OR=1.9) or ≥35kg/m(2) (OR=4.0), hospitalization (OR=7.9), nursing home confinement (OR=4.7), central venous (CV) catheter (OR=8.5) and any recent infection (OR=1.7). In a subgroup analysis, platelet count≥350×10(9)/L at time of cancer diagnosis was marginally associated with VTE (OR=2.3, p=0.07).

Conclusion: Cancer site, cancer stage≥2, liver metastasis, chemotherapy, progesterone, being underweight or obese, hospitalization/nursing home confinement, CV catheter, and infection are independent risk factors for incident VTE in active cancer patients.

Keywords: Cancer; Deep vein thrombosis; Epidemiology; Pulmonary embolism; Risk factors; Venous thromboembolism.