Medication therapy for outpatients with acute pulmonary embolism – a 5-year retrospective cohort study in one Canadian health region

Pulmonary Embolism (PE) is the third most common cardiovascular condition. Clinical guidelines recommend direct oral anticoagulants (DOACs) versus parenteral anticoagulants with or without Vitamin K antagonist (VKA). There was limited data on anticoagulant type, use and predictors for outpatients diagnosed with PE in our health region. We completed a retrospective cohort study of outpatients’ ≥18 years with acute PE from 2014 to 2019. Patients were identified from diagnostic imaging reports. Data collected to 90 days included drug and patient-specific characteristics, and simplified Pulmonary Embolism Severity Index (sPESI) score. Patient characteristics and treatments were compared using chi-square and analysis of variance tests. Multinomial logistic regression, adjusted for calendar year, was used to examine factors associated with acute PE treatment, and temporal trends in annual anticoagulant use were assessed using the Cochran-Armitage test for trend. A total of 785 patients were included, median age of 67 years (IQR 54–77), 42% male, and mean weight of 92 kg. Overall, 32% of patients had a sPESI score = 0, and 66% were admitted to hospital for treatment. Medications included DOACs (36%), parenteral anticoagulants alone (30%) or combined with VKA (22%), parenteral anticoagulants followed by DOACs (6%) or parenteral anticoagulants with VKA switched to DOACs (6%). Relative to parenteral anticoagulant alone, patients with malignancy were less likely to receive DOACs (RRR 0.06, 95% CI 0.03–0.11), parenteral anticoagulant transitioned to a DOAC (RRR 0.07, 95% CI 0.03–0.18), parenteral anticoagulant transitioned to VKA (RRR 0.09, 95% CI 0.05–0.19), or parenteral anticoagulant transitioned to VKA then a DOAC (RRR 0.04, 95% CI 0.02–0.12), and patients admitted to hospital were more likely to receive parenteral anticoagulant transitioned to VKA (RRR 2.91, 95% CI 1.60–5.29) or parenteral anticoagulant transitioned to VKA then a DOAC (RRR 3.88, 95% CI 1.25–11.99). Between 2015 and 2018, DOAC use rose from 14% to 50% (p for trend < 0.001) while parenteral anticoagulant transitioned to VKA fell from 43% to 14% (p for trend < 0.001). Patients with acute PE and malignancy were more likely to receive parenteral anticoagulation alone, and those admitted to hospital were more likely to receive parenteral anticoagulant transitioned to VKA, or to VKA then switched to a DOAC. Over the study period, the use of DOACs increased for the treatment of acute PE. This information may be used to inform future research and inform policies and care models for patients with PE.