Risks of thromboembolic events among patients diagnosed with metastatic pancreatic ductal adenocarcinoma treated with chemotherapy.

Abstract

380 Background: Clinical trials suggest that patients with metastatic pancreatic ductal adenocarcinoma (mPDA) are at a high risk of thromboembolic events (TEs) as a result of both disease and treatment. Real-world data on TE rates are limited for patients with mPDA. Methods: Using a retrospective cohort design, patients with mPDA aged ≥ 65 years and treated with chemotherapy during 2007-2012 were identified using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database. Patients enrolled in Medicare parts A, B, and D were followed from the start of first-line chemotherapy (index date) to the earliest of disenrollment from Medicare, death, or 12/31/2012. The baseline (BL) period was defined as 12 months prior to the index date. The incidence of TEs was calculated as the number of events per 100 person-years (PY) of follow-up (F/U) among patients without a BL TE. Anticoagulant use during F/U was categorized as preventive (before first TE, if any) and treatment (on or after first TE date) among patients with no BL TE. Results: Of 1,308 patients meeting the selection criteria, the mean age was 74 years, and 56% were female. The prevalence of TEs during the study period (BL or F/U) was 58% (n = 755). Excluding the 427 patients (33%) with TEs during BL, 328/881 (37%) of patients had a first TE during F/U, for an incidence rate of 85/100PY, including 29/100PY arterial and 59/100PY venous events. In the full study cohort, only 467/1,308 (36%) had a claim for any anticoagulant during the study period, although inpatient anticoagulant use is likely under-reported. Among patients receiving anticoagulants, 287/467 (61%) received low molecular weight heparin (LMWH). Preventive anticoagulant use was observed in 74/881 (8%) of patients without a BL TE; anticoagulation treatment was observed for 159/328 (48%) patients with a first TE during F/U. Conclusions: Real-world mPDA patients face a significant risk of TEs both before and after starting chemotherapy. Although inpatient use of anticoagulants including LMWH is incomplete in this database, it is clear that use of anticoagulants for treatment, and for prevention, of TEs is sub-optimal.