CARDIOVASCULAR JOURNAL OF AFRICA • Volume 33, No 4, July/August 2022 186 AFRICA Bleeding complications in patients on new oral anticoagulants for venous thromboembolism in Kenya Antonina Obayo, Mzee Ngunga, Jasmit Shah, Ahmed Sokwala, Anders Barasa Abstract Background: The incidence of bleeding complications in patients with venous thromboembolism (VTE) on new oral anticoagulants (NOACs) has not been widely studied in contemporary clinical practice in Africa. The purpose of this study was to determine the rates of major bleeding, clinically relevant non-major bleeding (CRNM) and minor bleeding associated with NOAC use Methods: A retrospective review was carried out of patients diagnosed with venous thromboembolism and treated with NOACs at the Aga Khan University Hospital, Nairobi, from January 2014 to December 2019. Clinical and outcome data were collected from medical records and the hospital mortality database. All patients with VTE aged > 18 years and initiated on NOACS were recruited. Patients with missing information were excluded. They were followed up from the time of commencement of oral anticoagulation to completion of therapy, or to the time of the first major bleed, CRNM or minor bleeding. Data on bleeding were obtained from the hospital database and through telephone interviews. Unadjusted rates of the first major bleeding event or CRNM were calculated as the number of bleeding events per 100 person-years. Results: Two hundred and forty-three patients with VTE were recruited and 222 (91.4%) were initiated on rivaroxaban, 12 (4.9%) on dabigatran and nine (3.7%) on apixaban, with a median follow up of 213 [interquartile range (IQR): 119–477] days. The median age of the patients was 57 (IQR: 45–71) years. A total of 64 bleeding events were identified in 50 (20.6%) patients. Overall, the incidence rate for bleeding events was 17.24 per 100 patient-years. The incidence rate of major bleeding was 3.79 per 100 person-years. Gastrointestinal bleeding was the most common major bleeding site. There were more females with bleeding events (70.7%) compared to males. Anaemia and the use of aspirin and other antiplatelets were associated with a higher incidence of major and CRNM bleeding [relative risk (RR) = 3.77, confidence interval (CI) = 1.37–10.39, p = 0.005 and RR = 8.89, CI = 2.06–38.33, p = 0.0003, respectively]. Conclusions: Most of these bleeds were minor, with the gastrointestinal tract being the most common source of major bleeding and menorrhagia being the commonest cause of bleeding. Anaemia and the use of aspirin were associated with a higher incidence of major bleeding. Keywords: new oral anticoagulants (NOAC), venous thromboembolism (VTE), deep venous thrombosis (DVT), pulmonary embolism (PE), bleeding Submitted 14/9/21, accepted 16/11/21 Published online 3/2/22 Cardiovasc J Afr 2022; 33: 186–192 www.cvja.co.za DOI: 10.5830/CVJA-2021-060 Venous thromboembolism (VTE) [comprising deep-vein thrombosis (DVT) or pulmonary embolism (PE) or both] is the third most common cardiovascular disorder,1 with an incidence of one to two cases per 1 000 people in the general population. VTE is associated with a high mortality rate, substantial healthcare costs and a high rate of recurrence.2 Until the advent of newer agents, the standard treatment of VTE included parenteral anticoagulants and vitamin K antagonists (primarily warfarin) with a target international normalised ratio (INR) of 2.0–3.0. The use of warfarin for longterm treatment of VTE has been associated with significant risk of bleeding. A pooled analysis of the EINSTEIN-DVT and -PE studies revealed that a first major or clinically relevant non-major (CRNM) bleeding event occurred in 388 (9.4%) patients treated with rivaroxaban compared with 412 patients (10.0%) in the standard-therapy group (heparin combined with vitamin K antagonists) (hazard ratio 0.93).3 Furthermore, the use of warfarin is associated with several drug and food interactions that could either increase or decrease its metabolism, and its use requires frequent monitoring of INR, which is both costly and cumbersome. The introduction of the new oral anticoagulants (NOACs) has revolutionised the treatment of both VTE and atrial fibrillation. These agents have a wider therapeutic window, a reduced need for monitoring and fewer interactions. Several phase 3 trials have highlighted the benefit of using NOACs versus warfarin4 for the treatment of VTE. Data on real-life patients in sub-Saharan Africa are anecdotal. Bleeding complications, although fewer compared to warfarin, still occur and are associated with high morbidity and mortality rates. The NOACs apixaban, dabigatran, edoxaban and rivaroxaban were efficacious in phase 3 randomised trials for acute and long-term treatment of venous thromboembolism.3,5,6 In the RE-COVER and RE-COVER II trials, dabigatran etexilate 150 mg had comparable efficacy to dose-adjusted Department of Medicine, Faculty of Health Sciences, Aga Khan University Medical College of East Africa, Nairobi, Kenya Antonina Obayo, MD, MMed, nzebby@gmail.com Mzee Ngunga, MD, MMed Jasmit Shah, PhD Ahmed Sokwala, MD, MMed Department of Medicine, Glostrup Hospital, University of Copenhagen, Copenhagen, Denmark Anders Barasa, MD, PhD
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