Factors influencing the use of thromboprophylaxis in cancer outpatients in clinical practice: A prospective study

•The incidence of VTE in cancer outpatients is not negligible.•Most cancer outpatients do not received pharmacologic thromboprophylaxis.•Cancer type and previous VTE seem the most relevant variables for decision-making.•In clinical practice, thromboprophylaxis use is influenced by other factors.

IntroductionCurrent clinical practice guidelines do not recommend routine pharmacological thromboprophylaxis in cancer outpatients receiving chemotherapy. However, a high proportion of cancer-associated venous thromboembolism (VTE) events occur in this setting. There are scarce data on the use of thromboprophylaxis in ambulatory cancer patients in real clinical practice.Material and methodsWe conducted a single-center prospective study aimed to evaluate the use and factors influencing pharmacological prophylaxis in consecutive cancer patients receiving ambulatory chemotherapy. Patients were followed for 90 days after inclusion.ResultsA total of 1108 patients were included. According to the Khorana score, 45.8% patients were classified as low-risk, 47.4% intermediate-risk and 6.8% as high-risk. Outpatient pharmacological prophylaxis was administered at any time during follow-up to 157 patients (14.2%) with a median duration of 42 days (range 1-90). Main factors influencing thromboprophylaxis were: previous history of VTE (odds ratio [OR], 19.11; 95% CI, 9.61-37.98), intercurrent hospitalization (OR, 5.40; 95% CI, 3.57-8.16), and gastrointestinal or gynecologic cancer (OR, 1.76; 95% CI, 1.11-2.80 and OR, 2.34; 95% CI, 1.05-5.26, respectively). During follow-up 58 (5.2%) VTE events were observed. Independent predictors of VTE were the site of malignancy (OR, 3.04; 95%CI, 1.20-7.71 and OR, 2.47; 95%CI, 1.21-5.01 for pancreas and lung cancer, respectively) and previous VTE (OR, 4.23; 95%CI, 1.26-14.27). Outpatient prophylaxis was associated with a lower risk of VTE during follow-up (OR, 0.30; 95%CI, 0.10-0.95).ConclusionsAlthough the type of malignancy appears as the most relevant variable for decision-making, additional efforts are required to identify patients at particular high thrombosis risk.