CPDIN OBJECTIVES


After completing this module you should: • Understand how DOACs contrast with warfarin. • Have a good understanding of the conditions for which NICE has approved DOACs in prophylaxis and / or treatment


• Appreciate how you can support and advise your patients in maintaining safe and effective anticoagulant therapy.


AUTHOR Roberta Tasker, Community Pharmacist


estimated that, of the 1.36 million AF cases in England, 474,000 of them were undiagnosed.1


A . The prevalence


of AF in Northern Ireland at that time was said to be 1.8% of the population. Across the UK, there are approximately 12,500 strokes each year. AF makes ones risk of stroke five times higher than would otherwise be the case, and an AF stroke is twice as likely to cause death. 2


.


In order to reduce risk of stroke in those diagnosed with AF an assessment of the need for ongoing anticoagulation will be made, using the CHA2DS2-VASc scale.3


. RISK FACTORS


Congestive heart failure Hypertension Age ≥ 75 Age 65-74


Diabetes mellitus


SCORE 1 1 2 1 1


Stroke/TIA/thrombo-embolism 2 Vascular disease Sex Female Your score


1 1 0


If the resultant score is 2 or more, the clinician will discuss with the patient the use of anticoagulants. This discussion can be aided using the Decision Support Tool from NICE. This online tool encourages partnership between patients and healthcare professionals when reaching a decision about the use of


18 - PHARMACY IN FOCUS


FOCUS ANTI-COAGULATION


This module is about anti-coagulation and atrial fibrillation


trial Fibrillation [or AF] is the most common heart rhythm disturbance. In 2017 it was


anticoagulants to reduce the risk of stroke, balanced with the risk of suffering a bleed.4


.


There are five oral anticoagulants licensed for use in the UK: warfarin, apixaban, dabigatran, edoxaban, and rivaroxaban. Warfarin remains as the sole Vitamin K antagonist [VKA] whilst the remaining four agents are referred to as New Oral Anticoagulants [NOACs] or, more recently as Direct Oral Anticoagulants [DOACs]. Any one of the four may be prescribed within their licenced authorization, instead of warfarin for those with AF, in order to prevent stroke. The 2018 European Society of Cardiology guidelines note that DOACs have emerged as the preferred choice, particularly in patients newly started on anticoagulation. 5


.


NICE has also approved the four DOACs for preventing systemic embolism and as options for treatment of Pulmonary Embolism [PE] and deep vein thrombosis [DVTT], and prevention of recurrent DVT and PE in adults after diagnosis of acute DVT. 6


.


In addition, apixaban, dabigatran, and rivaroxaban have been approved by NICE as options for the prophylaxis of venous thromboembolism in adults after elective hip or knee replacement surgery. Rivaroxaban has also been approved as an option for prophylaxis of atherosclerotic events (with aspirin alone, or with aspirin and clopidogrel, or ticlopidine) for people with


coronary heart disease and after an acute coronary syndrome in people with elevated cardiac biomarkers. It is also indicated for people with symptomatic peripheral artery disease at high risk of ischaemic events. 7


.


DOACs have an improved efficacy/safety ratio, a predictable anticoagulant effect without need for routine coagulation monitoring, and fewer food and drug interactions compared with VKAs [warfarin.] 8. This is based on data from randomized control trials [RCT] together with real world evidence [RWD]. That said, individual DOACs have their own unique characteristics which help determine in what circumstances they are prescribed. In terms of mechanism of action, apixaban, edoxaban and rivaroxaban are all factor Xa inhibitors whilst dabigatran is a direct thrombin inhibitor.


Besides the appropriate diagnosis, the other elements for a prescriber to


consider before choosing / recommending an oral anticoagulant, will include: -9


.


• Risk of bleeding [HAS-BLED score] • Renal function, measured as creatinine clearance


• Hepatic function • Active clinically significant bleeding • Current existing medication [eg enzyme inhibitors or inducers]


• Pregnancy or breastfeeding • Age


Unlike warfarin, the DOACs do not need regular INR monitoring. 10


.


However, regular follow-up and monitoring is still required, at least annually, to assess compliance; enquire about the presence of any adverse effect eg bleeding; assess for the presence of thromboembolic events. Eg symptoms of stroke, or breathlessness which might suggest a PE.] 10


.


The most common adverse effect of anticoagulants is bleeding. However, whilst there is an antidote for warfarin in the form of vitamin K, amongst the


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