CHALLENGES IN THE DISEASE BURDEN
SSA is undergoing an epidemiological transition: with increasing life
expectancy the increasing burden of non-communicable disease is
colliding with the pre-existing burden of infectious diseases. In the
context of anticoagulation, this transition is evident in the increasing
prevalence of (non-valvular) atrial fibrillation (AF), adding to the
large number of people requiring anticoagulation for valvular heart
disease (VHD), which in SSA is still mostly caused by rheumatic heart
disease (RHD).[23] This increase in indications for anticoagulation
is occurring amidst an uneven distribution of limited resources. For
example, there were only 57 centres in SSA capable to perform regular
open heart operations in 2011/2012 (one per 15 million population); 35
of these were in South Africa.[24] Figure 1 shows some examples of
SSA anticoagulation studies mentioning resource limitations.
{Figure 1 here}
A recent systematic review suggested that AF prevalence in SSA may be
higher than previously thought,[33] up to 4.3% in one Ethiopian
community-based survey.[34] Patients with AF in SSA have high
prevalence of concomitant stroke risk factors,[33,35] and should
therefore benefit from anticoagulation. However, despite clear
indications for anticoagulation, it is not always implemented in
SSA.[26,36–41] Indeed, in the multiregional RELY-AF
registry,[4] patients in Africa had the second-lowest use of oral
anticoagulation where indicated (19%, second only to China), and the
lowest TTR (33%).
RHD prevalence among school children in SSA is 1.5% to
3.0%.[42–47] In RHD registries, only two-thirds of patients with
an indication for oral anticoagulation received it,[5,37,48] and INR
control was in-range in only 28%.[5]
Venous thromboembolism (VTE) epidemiology in SSA has not been well
described,[49] but HIV infection is a well-established risk factor,
associated with a 1.5-fold increased hazard (95% confidence interval
1.1 to 2.0).[50] As the HIV pandemic epicentre, HIV-associated VTE
is commonly seen in SSA. In all the studies in Table 2, HIV prevalence
was higher among patients presenting with VTE than the background
prevalence. Interestingly, in a Ugandan study 9% of patients on
antiretroviral therapy attending routine outpatient follow-up were found
to have incidental deep venous thrombosis.[51]
{Table 2 here}