CHALLENGES ACCESSING ANTICOAGULATION
Vitamin K antagonists appear on most SSA countries’ essential medicine
lists.[64] Warfarin is the most commonly used, followed by
acenocoumarol.[64,65] Warfarin is cheap: a 5mg tablet cost 8 US
cents in rural Zambia[28] or 14 US cents in Uganda.[66] However,
being essential and cheap do not necessarily make medicines available or
accessible.[67] Essential medicines’ availability ranged from 25%
in public facilities to 49% in private facilities in Cameroon,[68]
and from 49% in public facilities to 71% in retail pharmacies in
Malawi.[69] Anecdotally, frequent stock-outs of warfarin have been
mentioned in some SSA studies.[22,29,70] To our knowledge, the only
study to systematically evaluate warfarin availability in SSA was
conducted in Uganda in 2017,[66] and showed that warfarin was
available on the survey day at 75/100 private pharmacies, 15/23 (65%)
private hospitals, and only 4/22 (18%) public hospitals, all randomly
sampled.[66]
DOACs were only available in 14/33 African countries surveyed in
2018,[71] and are often beyond the means of patients and public
health services. In South Africa, which has statutory private sector
medicine ceiling prices, one month’s supply of dabigatran, apixaban, or
rivaroxaban costs the equivalent of approximately 60 hours’ minimum
wage.[72] To our knowledge, no DOAC has yet been shown to be
cost-effective in any SSA country’s public health sector.[73]
A weak medicines regulatory environment in much of SSA means that
substandard and falsified medicines may be found on the market.[74]
We are not aware of any SSA data on the quality of warfarin on the
market, but in a medicines quality assessment across ten West and
Central African countries, there was fortunately no evidence of poor
quality acenocoumarol.[75]
Dedicated anticoagulation clinics (ACCs) using standardized approaches
may achieve better anticoagulation control than routine models of care,
where anticoagulation patients are seen as part of the general patient
mix.[76–81] Such ACCs are however not common in SSA;
anticoagulation is often managed in outpatient cardiology,
cardio-thoracic surgery, and haemato-oncology clinics[20,32,82] or
by individual health care workers who may not use standardized
approaches.[27,83] Prescribers of anticoagulation are often junior
with limited practice experience.[83]
A few studies investigated SSA health care workers’ knowledge,
attitudes, and beliefs about anticoagulation. In one such study 164
doctors and pharmacists at an Ethiopian tertiary hospital completed a
self-administered questionnaire.[84] Participants’ mean score on the
warfarin knowledge section was 10/15 correct answers, yet only 7%
identified their own lack of knowledge on warfarin as a barrier to
effective patient counselling.[84] Specific knowledge gaps
identified included drug-drug interactions, and the target INR range
appropriate to specific indications.[84] In a second study at the
same hospital, investigators directly observed the counselling
pharmacists provided during warfarin dispensing and found that only 10%
of patients were told what to do when they missed a dose, while
interactions and side effects were discussed in only 9% and 3% of
encounters, respectively.[85] In addition, just 24% of patients
were given an opportunity to ask questions at the dispensing encounter,
and only 40% of warfarin containers were labelled.[85] At a South
African academic hospital, in 86% of admissions for
over-anticoagulation with warfarin the cause of toxicity was not
identified by attending clinicians.[86] Drug-drug interactions with
warfarin, which went unrecognised by the attending clinicians, were
retrospectively identified by study investigators in 77% of these
patients.[86]
INR testing in centralised laboratories is the norm across SSA. As a
result, people living in rural settings often have no access to INR
monitoring. However, centralisation can even bypass people in urban
settings, as illustrated in some of the examples in Figure 1.
Centralised laboratory INR testing also means that results are delivered
with a long turn-around time,[27] and that patients may be required
to attend separate blood sampling and INR monitoring visits,[22,87]
driving up the expenses they incur.
The cost of INR testing has been identified as a barrier to
anticoagulation therapy in Zambian[88] and Ethiopian
reports.[29] We are aware of only one study systematically
investigating the availability and cost of coagulation profile testing
in SSA, conducted in Uganda in 2017.[66] At randomly sampled
facilities, coagulation profile testing was available at 13/22 (59%)
private hospitals, and 3/22 (14%) public hospitals,[66] at a median
price of US$8.30.
At least two different point-of-care (POC) INR monitors have been
validated in South African patients,[89–91] and there have been
reports of using POC INR monitors in ACCs in Namibia,[19]
Kenya,[7,70,92,93] and Nigeria.[87] Considering only the cost
per test, POC testing is more expensive than laboratory monitoring;
however, it may be cost-effective in some settings.[94] In SSA, most
sites that reported using POC testing received the monitors and test
strips through donations, and offered POC tests at a subsidised cost to
patients.[7,87,93]