Assessment of anticoagulation management in outpatients attending a warfarin clinic in Windhoek, Namibia

Jonkman, Lauren J.; Gwanyanya, Marvelous P.; Kakololo, Monika N.; Verbeeck, Roger K.; Singu, Bonifasius S.

doi:10.1007/s40267-019-00630-y

Cited by 12 publications

(27 citation statements)

References 24 publications

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“…This occurred despite regular INR monitoring. Unfortunately, our findings complement other recent sub-Saharan studies in South Africa, Namibia and Botswana, all reporting poor INR control, with mean/median TTR ranging from 29% to 47% [1,12,13]. It is known that a higher TTR is associated with increased efficacy of warfarin and reduction in bleeding complications [14].…”

Section: Discussionsupporting

confidence: 83%

A cross-sectional evaluation of five warfarin anticoagulation services in Uganda and South Africa

et al. 2020

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Introduction Warfarin is the most commonly prescribed oral anticoagulant in sub-Saharan Africa and requires ongoing monitoring. The burden of both infectious diseases and non-communicable diseases is high and medicines used to treat comorbidities may interact with warfarin. We describe service provision, patient characteristics, and anticoagulation control at selected anticoagulation clinics in Uganda and South Africa. Methods We evaluated two outpatient anticoagulation services in Kampala, Uganda and three in Cape Town, South Africa between 1 January and 31 July 2018. We collected information from key staff members about the clinics' service provision and extracted demographic and clinical data from a sample of patients' clinic records. We calculated time in therapeutic range (TTR) over the most recent 3-month period using the Rosendaal interpolation method. Results We included three tertiary level, one secondary level and one primary level anticoagulation service, seeing between 30 and 800 patients per month. Care was rendered by nurses, medical officers, and specialists. All healthcare facilities had on-site pharmacies; laboratory INR testing was off-site at two. Three clinics used warfarin dose-adjustment protocols; these were not validated for local use. We reviewed 229 patient clinical records. Most common indications for warfarin were venous thrombo-embolism in 112/229 (49%), atrial

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Section: Discussionsupporting

confidence: 83%

A cross-sectional evaluation of five warfarin anticoagulation services in Uganda and South Africa

et al. 2020

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“…At least two different point-of-care (POC) INR monitors have been validated in South African patients, [89][90][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.…”

Section: Challenges Accessing Anticoagulationmentioning

confidence: 99%

“…Where detailed dose adjustment algorithms do not exist, clinicians may make erroneous or even paradoxical dose adjustments. Reviews from Cameroon, [8] Ethiopia, [9,14] and Namibia [19] report dose increases after 4%-17% of supratherapeutic INRs and dose decreases after 4%-15% of subtherapeutic INRs. In addition, dose adjustments are often inappropriately large: While clinical trial evidence has shown that warfarin dose adjustments of 10-15% were associated with better outcomes, [102] the mean warfarin dose increase in one Ethiopian review was 58% in response to an INR of 1.5 to 1.9 against a target of 2.0 to 3.0.…”

Section: {Table 3 Here}mentioning

confidence: 99%

“…[9] In the Namibian example, more than half of patients with an INR >4 were over-corrected so that their subsequent INR was subtherapeutic. [19] Warfarin formulations other than 5mg are frequently not available in SSA, [6,22] making precision dosing difficult. Complicated weekly dosing schedules of alternating daily dosages which often require tablet splitting (sometimes into quarters) are used, potentially compromising the actual dose taken.…”

Section: {Table 3 Here}mentioning

confidence: 99%

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Improving anticoagulation in sub-Saharan Africa -- what are the challenges, and how can we overcome them?

Mouton

Blockman

Wiltshire

et al. 2020

Preprint

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Patients in sub-Saharan Africa generally have poor anticoagulation control. We review the potential reasons for this poor control, as well as the potential solutions. Challenges include the affordability and centralisation of anticoagulation care, problems with access to medicines and INR monitoring, the lack of locally-validated standardized dosing protocols, and low levels of anticoagulation knowledge among health care workers and patients. Increasing numbers of patients will need anticoagulation in the future because of the epidemiological transition in the region. We propose that locally-developed "warfarin care bundles" which address multiple anticoagulation challenges in combination may be the most appropriate solution in this setting currently.

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“…Although still scarce in many countries in this region, heart valve replacement surgery accounts for some need for long term anticoagulation in SSA. 25,26,54 In these patients, warfarin is superior to DOACs since the mechanism by which valve components induce thrombin generation would require much higher DOAC doses than those currently recommended. 55…”

Section: Anticoagulation In Af and Valvular Heart Diseasementioning

confidence: 99%

Anticoagulation in sub‐Saharan Africa: Are direct oral anticoagulants the answer? A review of lessons learnt from warfarin

Semakula

Kisa

Mouton

et al. 2021

Brit J Clinical Pharma

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Warfarin has existed for >7 decades and has been the anticoagulant of choice for many thromboembolic disorders. The recent introduction of direct-acting oral anticoagulants (DOACs) has, however, caused a shift in preference by healthcare professionals all over the world. DOACs have been found to be at least as effective as warfarin in prevention of stroke in patients with atrial fibrillation and in treatment of venous thromboembolism. In sub-Saharan Africa, however, the widespread use of DOACs has been hampered mainly by their higher acquisition costs. As the drugs come off patent, their use in sub-Saharan Africa is likely to increase. However, very few trials have been conducted in African settings, and safety concerns will need to be addressed with further study before widespread adoption into clinical practice.

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Assessment of anticoagulation management in outpatients attending a warfarin clinic in Windhoek, Namibia

Cited by 12 publications

References 24 publications

A cross-sectional evaluation of five warfarin anticoagulation services in Uganda and South Africa

A cross-sectional evaluation of five warfarin anticoagulation services in Uganda and South Africa

Improving anticoagulation in sub-Saharan Africa -- what are the challenges, and how can we overcome them?

Anticoagulation in sub‐Saharan Africa: Are direct oral anticoagulants the answer? A review of lessons learnt from warfarin

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