DUBROVNIK, CROATIA – An updated scoring system can more accurately identify lymphoma patients who may require thromboprophylaxis, according to researchers.
The revised scoring system, ThroLy, proved more effective than other systems for predicting thromboembolic events in lymphoma patients, with a positive predictive value of 22%-25%, a negative predictive value of 96%, sensitivity of 56%-57%, and specificity of 85%-87%.
Darko Antic, MD, PhD, of the University of Belgrade in Serbia, presented these findings at Leukemia and Lymphoma, a meeting jointly sponsored by the University of Texas MD Anderson Cancer Center and the School of Medicine at the University of Zagreb, Croatia.
Dr. Antic said that he and his colleagues developed ThroLy because other systems used to predict venous thromboembolism (VTE) are not quite right for lymphoma. He noted that the Padua score is not designed for cancer patients and the Khorana score is predominantly used for solid tumor malignancies.
The ThroLy scoring system is based on variables used in the Padua and Khorana systems, as well as variables that are specific to lymphoma patients.
In a previous study, the researchers found several variables that were independently associated with risk for VTE in lymphoma, including previous VTE, previous acute MI or stroke, mediastinal involvement, high body mass index, reduced mobility, extranodal localization, neutropenia, and hemoglobin less than 100 g/L (Am J Hematol. 2016 Oct;91[10]:1014-9).
In an initial version of the ThroLy scoring system, previous VTE, previous acute MI/stroke, obesity, and mediastinal involvement were all worth two points, and the other factors were worth a single point in the ThroLy system.
Patients with scores of 0 to 1 were considered low risk, patients with scores of 2 to 3 were considered intermediate risk, and patients with scores of 4 or greater were considered high risk.
To validate and refine ThroLy, Dr. Antic and his colleagues used it to assess 1,723 lymphoma patients treated at eight institutions in Austria, Croatia, France, Jordan, Macedonia, Spain, Switzerland, and the United States.
Patients had indolent non-Hodgkin lymphoma, aggressive non-Hodgkin lymphoma, chronic lymphocytic leukemia/small lymphocytic lymphoma, and Hodgkin lymphoma. Most subjects (84%) were outpatients. A total of 9%of patients had thrombosis, with 7% having VTE.
ThroLy had a positive predictive value of 17%, compared with 11% with Khorana and 13% with Padua. The negative predictive value was 93%, 92%, and 95%, respectively. The sensitivity was 51% with ThroLy, 42% with Khorana, and 70% with Padua; specificity was 72%, 64%, and 52%, respectively.
“The positive predictive value was low [with ThroLy] but definitely higher than the positive predictive value of the other two [scoring systems],” Dr. Antic noted.
Updated models
To further improve ThroLy, the researchers updated the system, creating two new models. Model 1 included the type of lymphoma/clinical stage (1 point), previous VTE (5 points), reduced mobility (2 points), hemoglobin less than 100 g/L (1 point), and the presence of vascular devices (1 point). Model 2 included all of the variables in Model 1 plus the thrombophilic condition, which was worth 1 point.
Patients were considered low risk if they scored 2 points or lower and high risk if they scored more than 2 points.
For Model 1, the positive predictive value was 22%, the negative predictive value was 96%, the sensitivity was 56%, and the specificity was 85%. For Model 2, the positive predictive value was 25%, the negative predictive value was 96%, the sensitivity was 57%, and the specificity was 87%.
There were no major differences in model discrimination and calibration based on the country in which a patient was treated or whether the patient was treated in an inpatient or outpatient setting.
Dr. Antic did not report any conflicts of interest. The Leukemia and Lymphoma meeting is organized by Jonathan Wood & Association, which is owned by the parent company of this news organization.