Hospitalized patients also at risk for VTE
Hospitalized patients also at risk for VTE
May warrant consideration for prophylaxsis
Research conducted by Policy Analysis, Inc., Brookline, MA, and reported in the American Journal of Health-System Pharmacy, found that the risk of clinical venous thromboembolism (VTE) among medically ill patients admitted to a hospital, although less than that of patients undergoing major surgery, is not negligible.1 The authors report that patients with a history of recent VTE or surgery, those who are admitted to an intensive care unit, those with an admitting diagnosis of heart failure, and those with acute cancer are at especially high risk of VTE and deserve increased consideration for prophylaxis.
Deep-vein thrombosis (DVT) and pulmonary embolism (PE)—referred to together as venous thromboembolism—are important causes of disability and death, according to corresponding author Gerry Oster, PhD, Policy Analysis vice president. Most VTE cases occur among people living in the community, and not in nursing homes, but risk for VTE is more than 260-fold higher among those who are hospitalized. Although a recent major surgery is the greatest risk factor for VTE, the number of cases among medical and surgical patients is roughly equal, as there are far more medical than surgical admissions.
In research supported by drug company Sanofi-Aventis, Oster and colleagues conducted a retrospective cohort study to estimate the risk of VTE in hospitalized medically ill patients. They identified all persons age 40 and older who were admitted to a hospital between January 1, 1998, and June 30, 2002, for reasons other than traumatic injury and who did not undergo surgery. Patients were followed for 90 days from the date of their earliest such hospital admission for the occurrence of clinical VTE.
The researchers characterized the study population in terms of selected demographic and clinical characteristics at index admission, including age, gender, principal diagnosis group (based on a classification scheme from the U.S. National Hospital Discharge Survey), geographical region, and payer type. The presence of several established VTE risk factors during the index admission was also noted, including acute coronary syndrome, stroke, chronic obstructive pulmonary disease, heart failure, and admission to an ICU. Study subjects were further characterized according to whether they had any of these additional established VTE risk factors at the index admission or during the immediately preceding six month period: cancer, post-thrombotic syndrome (but not as principal diagnosis at the index admission), and neurological disorders with plegia, paresis, or paralysis. Finally, any diagnosis of DVT or PE during the six month history period before the index admission was obtained.
Primary study endpoint
The researchers said their primary measure of interest was the occurrence of clinical VTE between the index admission and the end of the 90 day follow-up period.
A total of 92,162 patients met all inclusion criteria for the study. Mean age was 71 years. Some 54% of study subjects were women. About one-half had a principal diagnosis involving either the circulatory or respiratory system. During the index admission or the previous six months, 2.25% of study subjects had a recorded principal or secondary diagnosis of post-thromboting syndrome. And during the index admission, 10.5% of patients had a diagnosis of acute coronary syndrome; 9.7%, stroke; and 15%, heart failure. One-half of all study patients were admitted to an ICU or critical care unit (CCU).
The cumulative incidence of clinical VTE at 90 days was 1.59%, with 18% of the cases occurring post-discharge. Inpatient mortality (unadjusted) was 42% higher for patients who developed VTE than for those who did not. Significant risk factors for VTE included peripheral arterial disease during admission; chronic obstructive pulmonary disease during index admission; any diagnosis of post-thrombotic syndrome, neurological disease with paresis or paralysis, cancer, or heart failure; a diagnosis of VTE during the six-month history period; admission to an ICU or CCU; and an operating room procedure during the 30 days before the index admission.
The researchers said that while most cases of clinical VTE among hospitalized medically ill patients occur during hospitalization, almost one in five events occurred post-discharge. "To the best of our knowledge," they said, "our study is the first to examine VTE risk following hospital discharge among these patients. In studies of hip and knee arthroplasty patients, in contrast, 49% to 81% of all cases of clinical VTE have been reported to occur during the three months following hospital discharge. While the risk of post-discharge VTE appears to be lower in medical patients than in those who have undergone major orthopedic surgery, it nonetheless should be of concern."
Risk factors that the researchers found to be independent predictors of VTE such as a history of cancer, history of VTE within six months of index admission, an operating room procedure within 30 days of index admission, and a diagnosis of heart failure or peripheral artery disease during index admission are generally well known, the researchers said. The only exception is peripheral artery disease during the index admission, but they said that finding could reflect a diagnostic bias based on increased scrutiny of the lower extremities in the disease. The researchers said they did not find that other variables previously reported to be important predictors such as stroke and acute coronary syndrome were related to VTE risk. In fact, they said, a diagnosis of coronary artery disease was found to be associated with a decreased risk of VTE, a finding that probably reflects the widespread use of antithrombotic agents for preventing and treating arterial thrombosis.
[Editor's note: Contact Dr. Oster at [email protected].]
Reference
- Oster, G. Risk of Venous Thromboembolism Among Hospitalized Medically Ill Patients. Am J Health-Syst Pharm. 2006;63(20):S16-S22.
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