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}