Incidence of Venous Thromboembolism (VTE) in Patients Prescribed Megestrol for Appetite Stimulation

First Author: Aysha Ahmed, MS Sherry Williams, PharmD Christy Thai, PharmD Leah Clark, PharmD Xuihua Zhao, MPH Sowmya Nanjappa, MD Smitha Pabbathi, MD, FACP

Introduction: Cachexia and anorexia occur in 50-80% of cancer patients. In cancer patients, it is associated with shorter survival, treatment failure, early treatment termination, declining functional status, and reduced quality of life. Megestrol acetate is a synthetic derivative of progesterone commonly used to treat cancer-related cachexia. Megestrol use is associated with thromboembolism among other adverse events. VTE has been reported to occur in 4.9% to 32% of patients on megestrol therapy. This is of particular concern since the risk of VTE in patients with cancer is already increased several-fold. The primary endpoint is to determine whether a higher incidence of VTE exists in cancer patients prescribed megestrol for appetite stimulation when compared to cancer patients not prescribed the drug.

Methods: This is a retrospective study conducted via chart review with two groups: study (patients prescribed megestrol) and control (patients not prescribed megestrol) at a National Cancer Institute (NCI) designated cancer center. The sample size was 435 patients (study group n=217; control group n=218) attaining a power of 90%. Patients who were prescribed megestrol were identified using the inpatient pharmacy department charge codes. Sex, high risk disease, active chemotherapy, advanced cancer stage, advanced age, poor performance status (ECOG greater than or equal to 3), major surgery, prior history of VTE, and high dose dexamethasone use were the variables examined. Exclusion criteria included patients less than 18 years old, those outside of the time frame of the study (1.5 years), and those without cancer diagnosis. Chi-square test, non-parametric Wilcoxon, and a multi- variable logistic regression model were used.

Results: Uni-variable analysis showed that advanced cancer stage, active chemotherapy, active cancer, and poor performance status were statistically significant (p value < 0.0001). After adjusting for these, patients in the study group were noted to have a higher incidence of VTE with odds ratio of 3.1 (95% CI 1.3-7.7) with p value <0.0001. Sex, advanced age, high risk disease, prior VTE history, major surgery, and high dose dexamethasone use were not statistically significant. Patients with advanced cancer stage had a higher incidence of VTE when prescribed megestrol compared to control (odds ratio 3.4; 95% CI 0.975-12.09).

Conclusions: Patients with cancer prescribed megestrol for appetite stimulation have a higher incidence of VTE, especially patients with advanced cancer stage. Development of VTE in this population can further worsen quality of life and create unnecessary burden with anticoagulation treatment and its complications. The initiation of alternative appetite stimulants that do not further increase the risk of VTE in cancer patients should be considered. To our knowledge, this study is the largest to date to analyze the incidence of VTE in cancer patients prescribed megestrol and can impact the way practitioners treat cachexia/anorexia in cancer patients.

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