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]