May 07, 2014
By Shira Klapper, Senior Writer/Editor
A new study in the Journal of Clinical Oncology (JCO) online ahead of print, May 5, reports that a high number of hospitalized patients with cancer receive thrombophrolyaxis, the practice of prescribing anticoagulants to reduce the risk of venous thromboembolism (VTEs). VTEs are a frequent complication of cancer that often lead to serious illness and death.
The study, “A Pattern of Frequent But Non-Targeted Pharmacologic Thromboprophylaxis of Hospitalized Cancer Patients at Academic Medical Centers: A Prospective, Cross-Sectional, Multi-Center Study,” found that a robust 74% of hospitalized patients with cancer are receiving thromboprophylaxis. This data is encouraging in light of previous studies showing that patients with cancer were receiving thromboprophylaxis at a much lower rate than those with other diseases.
However, this good news does come with a major caveat: While rates of thromboprophylaxis were found to be high, the medication was not necessarily dispensed according to risk, that is, with regard to the presence or absence of individual characteristics that raised or lowered a patient’s chance of developing a VTE.
Wide Support for Thromboprophylaxis
The practice of prescribing prophylactic anticoagulants is based on several studies showing that high-risk, hospitalized patients who received such anticoagulants as heparin and enoxaparin had significantly fewer VTEs. According to first author, Jeffrey Zwicker, MD, those studies had a substantial influence on the use of thromboembolism among hospitalized patients, even as data in cancer populations remained lacking.
“Government agencies mandated the practice, it’s considered a competency measure and a leading safety concern in hospitals,” said Dr. Zwicker.
The central importance of thromboprophyalxis was drummed into doctors and hospitals by guidelines from several major medical organizations. In 2007, the American Society of Clinical Oncology (ASCO) released guidelines recommending the wide use of thromboprophylaxis among hospitalized patients with cancer, except when contraindicated. In 2013 ASCO released updated guidelines advocating for a more nuanced use of thromboprophylaxis based on individual patient risk. Similar reports advocating thromboprophylaxis came out of the National Comprehensive Cancer Network and the American College of Chest Physicians (ACCP).
In the wake of these reports, hospitals across the country began to increase their rates of prescribing anticoagulants to patients at high risk for VTEs. However, thromboprophyalxis among hospitalized patients with cancer remained lower than among patients with other diseases
One of the first prospective studies of its kind
Dr. Zwicker and his colleagues wanted to further investigate these low rates of thromboprophylaxis among hospitalized patients with cancer. For their study, they decided to use a prospective study design that followed patients as they were admitted for care. Most previous studies gleaned data by retrospectively looking back at patient records and population databases.
In addition to assessing the rate of thromboprophylaxis, the research team also set out to assess the factors that drove prescription of anticoagulants.
A closer look at individual risk
Ultimately, the study looked at 775 patients from five academic hospitals across the country. Patients were eligible for the study if they had been treated for cancer within the last six months. Importantly, the study looked closely at patients’ Padua Prediction Scores, developed to identify the level of patient risk for VTEs during hospitalization. ACCP advocates using Padua scores to determine whether or not a patient should receive pharmacologic thromboprophylaxis
When Dr. Zwicker and his team analyzed the data, they found the rate of thromboprophylaxis to be at the encouraging rate of 74% among patients who were eligible for anticoagulants. They also identified six main, independent factors that determined whether anticoagulants were prescribed. The strongest predictor of thromboprophylaxis was a history of VTE, an example of practice aligning with evidence; after all, patients who have had VTEs in the past are at a significantly increased risk of having future VTEs. However, other factors found to be predictive of thromboprophylaxis did not appear to align with existing evidence regarding VTE risk. For example, patients in the study who had received chemotherapy were less likely to receive anticoagulant treatment, even though data has shown that chemotherapy is an established risk factor for VTE.
And in another example of practice not aligning with existing evidence, the research team found that a high overall Padua was not independently associated with increased odds of receiving anticoagulant prophylaxis.
“Among the patients identified as high-risk based on Padua score, around 20% did not receive thromboprophylaxis,” said Dr. Zwicker. “And in patients identified as low-risk, two-thirds did receive thromboprophylaxis.” This high rate of thromboprophylaxis among low-risk patients is concerning in light of evidence showing that low-risk patients appear not to benefit from pharmacologic thromboprophylaxis.
Commenting on this data, Dr. Zwicker stated, “The factors that predict the use of thromboprophylaxis were not necessarily based on existing evidence.”
For Dr. Zwicker, this “one-size-fits-all” approach to prescribing anticoagulants shows that hospitals are not necessarily adhering to the guidelines put forth by ACCP and ASCO; in their reports, both organizations advised doctors to carry out more individual risk assessment before giving thromboprophylaxis to hospitalized patients.
“ACCP guidelines actually recommend against the use of pharmacologic thromboprophylaxis among lower-risk patients, not only in cancer patients, but in all patients,” said Dr. Zwicker. “They have really come out in support of more nuanced, more measured recommendation for doctors prescribing anticoagulants.”
The study calls for more research that identifies which patients with cancer in fact benefit from thromboprophylaxis and whether certain high-risk populations require more aggressive thromboprophylaxis strategies. Until then, Dr. Zwicker said, “It’s important that health systems and physicians be aware that the current standard practice requires some attention.”
Dr. Jeffrey Zwicker, MD, is an Assistant Professor of Medicine at Beth Israel Deaconess Medical Center and Harvard Medical School, in Boston.
Click here to read the abstract
Click here to read the PDF.
Zwicker, J, Rojan, A, Campigotto, F, et al. A pattern of frequent but non-targeted pharmacologic thromboprophylaxis of hospitalized cancer patients at academic medical centers: a prospective, cross-sectional, multi-center study. J Clin Oncol. 2014; Published online ahead of print 5.5.2014.
The Exclusive Coverage series on ASCO.org highlights selected research from JCO with additional perspective provided by the lead or corresponding author.
@ 2014 American Society of Clinical Oncology