Infection, other factors may increase risk for VTE hospitalization

Infection, treatment with erythropoiesis-stimulating agents, and blood transfusion may increase risk for hospitalization due to venous thromboembolism (VTE), according to a new study.

Researchers used data from the Health and Retirement Study, a nationally representative, ongoing, longitudinal study of Americans at least 51 years of age, to perform a case-crossover study examining risk factors for VTE hospitalization. Data from the study were linked with Medicare files for hospital and nursing home stays and emergency department, outpatient and home health visits from 1991 to 2007. The authors compared exposures to potential risk factors in the 90 days before hospital admission in patients admitted with a principal diagnosis of deep venous thrombosis or pulmonary embolism to the same patients' exposures during the four previous 90-day periods. A 90-day washout period was observed between the risk and comparison periods. The main outcome was hospitalization for VTE. The study results were published early online April 3 by Circulation.

A total of 16,781 patients with 399 index VTE hospitalizations were included. The most common predictor of hospitalization for VTE was infection (52.4% of risk periods), with adjusted incidence rate ratios (IRRs) of 2.90 (95% CI, 2.13 to 3.94) for all infection, 2.63 (95% CI, 1.90 to 3.63) for infection without a previous stay in a hospital or skilled nursing facility and 6.92 (95% CI, 4.46 to 10.72) for infection with a previous stay in a hospital or skilled nursing facility. An association was also seen between VTE hospitalization and treatment with erythropoiesis-stimulating agents (IRR, 9.33; 95% CI, 1.19 to 73.42) and blood transfusion (IRR, 2.57; 95% CI, 1.17 to 5.64). Major surgeries, fractures, immobility and chemotherapy also appeared to contribute to VTE hospitalization risk.

The authors acknowledged that their study database was relatively small and that information on oral medications was not available, among other limitations. However, they concluded that infection, erythropoiesis-stimulating agents and blood transfusion are associated with increased risk for VTE hospitalization and that risk prediction algorithms should be updated to include these factors.

An accompanying editorial called for additional studies using “more robust” data sets to confirm and expand on these findings, especially in younger patients, but agreed that “acute infection, particularly a more severe infection that requires hospitalization, should be considered a trigger for acute VTE.” The study's findings “provide evidence suggesting that blood transfusion and treatment with erythropoiesis-stimulating agents should now be considered as possible triggers for acute VTE in non-cancer patients,” the editorialist added.