INTRODUCTION
Anticoagulation is used to treat and prevent venous thrombosis and to
prevent intracardiac thrombosis due to some structural heart diseases or
dysrhythmias. Depending on the indication, treatment may be lifelong.
Over-anticoagulation may result in bleeding and under-coagulation in
thrombotic complications, including stroke. With the advent of direct
oral anticoagulants (DOACs), there is increased choice of drugs
available. However, vitamin K antagonists such as warfarin remain the
most widely used oral anticoagulants, and form the focus of this
article.
When using vitamin K antagonists, the degree of anticoagulation is
measured by the international normalised ratio (INR), and a patient’s
longitudinal anticoagulation control can be described by the proportion
of INRs which fall in the therapeutic range (PTR), or by the proportion
of time spent in the therapeutic range (TTR), interpolating INR results
for the time between actual INR measurements. Patients in sub-Saharan
Africa (SSA) have poor anticoagulation control as measured by their
PTR/TTR, which is evident from trials,[1–3] large multisite
registries,[4,5] and smaller observational studies (Table 1).
{Table 1 here}
In this review, we explore potential reasons for this poor
anticoagulation control.