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

Anticoagulation control among patients on vitamin K antagonists in nine countries in Sub-Saharan Africa

Vitamin K antagonists (VKA) is the primary anticoagulant in most settings of Sub-Saharan Africa. Understanding the quality of anticoagulation services in the continent is vital in optimising the intended benefits. This study assessed the quality of anticoagulation and associated factors among VKA-treated patients in nine SSA countries. We conducted a retrospective cohort study of randomly selected patients on anticoagulation from 20 clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania, and South Africa. Eligible participants were those on VKAs for at least three months and with at least four international normalised ratios (INR) results in 2019-2021. We report the proportion of INR values in the therapeutic range, time-in-therapeutic range (TTR) using the Rosendaal method, and the proportion of patients with TTR ≥ 65% (optimal anticoagulation). The mean age was 51.1(16.1) years, and 64.2% were women. The most common indications for VKA included venous thromboembolism (29.6%), prosthetic valves (26.7%) and atrial fibrillation/flutter (30.1%). We analysed 6743 INR tests from 1011 participants, and of these, 48.5% were sub-therapeutic, 34.1% therapeutic, and 17.4% were supratherapeutic relative to disease-specific reference ranges. TTR was calculated for 660 patients using 4927 INR measurements. The median (interquartile range [IQR]) TTR was 35.8(15.9,57.2) %. Optimal anticoagulation control was evident in 19.2% of participants, varying from 2.7% in Tanzania to 23.1% in Ethiopia. The proportion of patients with TTR ≥ 65% was 15,4% for prosthetic heart valves, 21.1% for venous thromboembolism and 23.7% for atrial fibrillation or flutter. Countries with universal health coverage had higher odds of optimal anticoagulation control (adjusted odds ratio (aOR) 1.79, 95% confidence interval [CI], 1.15- 2.81, p = 0.01). Patients on VKAs for different therapeutic indications in SSA had suboptimal TTR. Universal health coverage increased the odds of achieving TTR by 79%. The evidence calls for more intensive warfarin management strategies in SSA, including providing VKA services without out-of-pocket payments.

Attainment of Target in Therapeutic Range of International Normalized Ratio and Correlates Among Patients on Warfarin Therapy at Jimma Medical Center, Jimma, Ethiopia

PURPOSE

Warfarin is effective therapy to prevent thromboembolic complications of venous thromboembolism, atrial fibrillation, and cardiac thrombus, among valvular heart diseases, including in patients treated with prostheses and/or repair. Its optimum effect is achieved when the international normalized ratio (INR) is in the target therapeutic range, but a subtherapeutic level increases risk of thromboembolism and complications. This study aimed to assess the attainment of target therapeutic range, proportion, and factors associated with subtherapeutic level of warfarin.

METHODS

A hospital-based cross-sectional study was conducted at Jimma Medical Center in Jimma, Ethiopia, from October 1, 2020 through December 30, 2021. All patients on warfarin and attending Medical Follow-Up Clinics of Jimma Medical Center during the study period were included. Data were collected using structured questionnaires and then analyzed using EpiData Manager software, version 3.1 (EpiData Association). χ2 Tests and logistic regression models were used to assess relationships among variables.

FINDINGS

Of 196 patients on warfarin, ∼60% were taking it for atrial fibrillation, followed by deep venous thrombosis, women accounted for 61.7% of patients, and mean (SD) age was 43 (7) years. Most patients (61.7%) lived in rural areas and 44.9% farmed to earn a living. Most of the study participants (51.5%) had a very low monthly income of less than USD50. Most of the patients (n = 107 [54.6%]) were advised on dietary selections while on warfarin and approximately two-thirds (n = 70 [65.4%]) were adherent to the advice. Most participants (n = 118 [60.2%]) were poorly adherent to warfarin therapy and more than two-thirds of them discontinued warfarin for financial reasons. Mean (SD) duration of warfarin therapy was 15.53 (18.92) months (range 1-90 months). Most of the respondents (n = 109 [55.6%]) had subtherapeutic INR and 21 (10.7%) were in the supratherapeutic range. Although the mean (SD) time in therapeutic range was 25.03% (24.17% [range 0-80%]), in most patients (n = 166 [84.7%]), it was <60%. Poor adherence (adjusted odds ratio = 6.13; 95% CI, 3.31-28.10), shorter duration of warfarin (<12 months; adjusted odds ratio = 0.104; 95% CI, 0.012-0.875), and presence of comorbidity (adjusted odds ratio = 0.035; 95% CI, 0.004-0.323) were significantly associated with subtherapeutic INR.

IMPLICATIONS

Attainment of therapeutic INR among patients on warfarin therapy is suboptimal. This was evidenced by a significant number of patients with low time in therapeutic range, as well as INR. Poor adherence to warfarin therapy, shorter duration since initiation of warfarin, and presence of comorbid illnesses were significantly associated with subtherapeutic INR. This can lead to complications of atrial fibrillation, including thrombus formation and subsequent cardioembolic stroke, venous thromboembolism, and others, leading to morbidity, increased mortality, and poor quality of life. Therefore, providing health education and treatment for comorbidities may improve adherence, which may also improve attainment of therapeutic INR and reduce complications and improve quality of life.

The Case for Pre-Emptive Pharmacogenetic Screening in South Africa

Lack of equitable representation of global genetic diversity has hampered the implementation of genomic medicine in under-represented populations, including those on the African continent. Data from the multi-national Pre-emptive Pharmacogenomic Testing for Preventing Adverse Drug Reactions (PREPARE) study suggest that genotype guidance for prescriptions reduced the incidence of clinically relevant adverse drug reactions (ADRs) by 30%. In this study, hospital dispensary trends from a tertiary South African (SA) hospital (Steve Biko Academic Hospital; SBAH) were compared with the drugs monitored in the PREPARE study. Dispensary data on 29 drugs from the PREPARE study accounted for ~10% of total prescriptions and ~9% of the total expenditure at SBAH. VigiLyze data from the South African Health Products Regulatory Authority were interrogated for local ADRs related to these drugs; 27 were listed as being suspected, concomitant, or interacting in ADR reports. Furthermore, a comparison of pharmacogene allele frequencies between African and European populations was used to frame the potential impact of pre-emptive pharmacogenetic screening in SA. Enumerating the benefit of pre-emptive pharmacogenetic screening in SA will only be possible once we initiate its full application. However, regional genomic diversity, disease burden, and first-line treatment options could be harnessed to target stratified PGx today.

Association of sex with major bleeding risks in sub-Saharian anticoagulated patients with mechanical heart valves: A cohort study from the Khartoum Emergency Salam Centre

BACKGROUND

Rheumatic heart disease (RHD) with mechanical heart valve (MHV) replacement is common in Africa. However, MHV requires lifelong anticoagulation that could have a particular impact in women in reproductive age.

METHODS

We report data of a prospective observational cohort study conducted between August 2018 and September 2019 in MHV patients in the Salam Centre for Cardiac Surgery built in Khartoum by Emergency, an Italian Non-Governmental Organization, to evaluate bleeding risk, its associated determinants, and the impact of lifelong anticoagulation in fertile women.

RESULTS

We studied 3647 patients (median age 25.1 years; 53.9% female). During follow-up [median time 1.1 (0.1-1.2) years], we recorded 85 major bleedings (rate 2.16 × 100 pt-years), Major bleedings occurred more frequently among women (64/85 cases, 75.3%; rate 3.0 × 100 pt-years), compared to men (21/85 cases, 24.7%; rate 1.16 × 100 pt-years) (RR 2.6; 95% CI 1.6-4.5; p = 0.0001). Multivariate analysis was performed to identify variables associated with major bleeding, and female sex was the only risk factor significantly associated, whereas aspirin treatment and higher INR target showed a non-significant trend for higher bleeding risk. Thirty-two/85 (37.6%) of major bleedings were metrorrhagias. When we calculate the incidence of major bleedings after the exclusion of gynecological events, no sex differences in the bleeding risk were found (HR 1.3, 95% CI 0.8-2.3; p = 0.3).

CONCLUSIONS

Bleeding risk of young MHV patients on oral anticoagulant therapy is higher among women, mainly due to metrorrhagia. Women in the reproductive life are at high risk for gynecological bleeding when treated with anticoagulants.

The Budget Impact Analysis of Adopting Direct Oral Anticoagulants for Stroke Prevention in Nonvalvular Atrial Fibrillation Patients in Malawi

OBJECTIVES

This study aimed to estimate the budget impact of adopting direct oral anticoagulants (DOACs) for stroke prevention in patients with nonvalvular atrial fibrillation in Malawi after the inclusion of DOACs in the World Health Organization's essential medicine list.

METHODS

A model was developed in Microsoft Excel. An eligible population of 201 491 was adjusted with 0.05 % incidence rate and mortality rates yearly according to the treatments. The model estimated the implication of supplementing rivaroxaban or apixaban to the standard treatment mix (also the comparator), thus warfarin and aspirin. The current market share of 43% aspirin and 57% warfarin was adjusted proportionally with 10% DOAC uptake in the first year and 5% annually over the subsequent 4 years. Clinical events of stroke and major bleeding from the ROCKET-AF and ARISTOTLE trials were used because health outcome indicators affect resource utilization. The analysis was conducted solely from the Malawi Ministry of Health perspective and it considered direct costs over 5 years. The sensitivity analysis involved varying drug costs, population, and care costs from both public and private sectors.

RESULTS

The research suggests that despite potential savings of $6 644 141 to $6 930 812 in stroke care because of fewer stroke events, the total Ministry of Health healthcare budget (approximately $260 400 000) may increase by between $42 488 342 to $101 633 644 in 5 years because drug acquisition costs are greater than savings.

CONCLUSIONS

With a fixed budget and current DOACs prices, Malawi can consider using DOACs in patients at the highest risk while waiting for cheaper generic versions.

A "Bundle of Care" to Improve Anticoagulation Control in Patients Receiving Warfarin in Uganda and South Africa: Protocol for an Implementation Study

BACKGROUND

The quality of warfarin anticoagulation among Sub-Saharan African patients is suboptimal. This is due to several factors, including a lack of standardized dosing algorithms, difficulty in providing timely international normalized ratio (INR) results, a lack of patient feedback on their experiences with treatment, a lack of education on adherence, and inadequate knowledge and training of health care workers. Low quality of warfarin anticoagulation, expressed as time in therapeutic range (TTR), is associated with higher adverse event rates, including bleeding and thrombosis, and ultimately, increased morbidity and mortality. Processes and interventions that improve this situation are urgently needed.

OBJECTIVE

This study aims to evaluate the implementation of the "warfarin bundle," a package of interventions to improve the quality of anticoagulation and thereby clinical outcomes. The primary outcome for this study is TTR over the initial 3 months of warfarin therapy.

METHODS

Patients aged 18 years or older who are newly initiated on warfarin for venous thromboembolism, atrial fibrillation, or valvular heart disease will be enrolled and followed up for 3 months at clinics in Cape Town, South Africa, and Kampala, Uganda, where the warfarin bundle is implemented. A retrospective review of the clinical records of patients on warfarin treatment before implementation (controls) will be used for comparison. This study uses a mixed methods approach of the implementation of patient- and process-centered activities to improve the quality of anticoagulation. Patient-centered activities include the use of clinical dosing algorithms, adherence support, and root cause analysis, whereas process-centered activities include point-of-care INR testing, staff training, and patient education and training. We will assess the impact of these interventions by comparing the TTR and safety outcomes across the 2 groups, as well as the cost-effectiveness and acceptability of the package.

RESULTS

We started recruitment in June 2021 and stopped in August 2022, having recruited 167 participants. We obtained ethics approval from the University of Cape Town Faculty of Health Sciences Human Research Ethics Committee, the Provincial Health Research Committees in South Africa, the Joint Clinical Research Centre Institutional Review Board, Kampala, and the University of Liverpool Research Ethics Committee. As of February 2023, data cleaning and formal analysis are underway. We expect to publish the full results by December 2023.

CONCLUSIONS

We anticipate that the "bundle of care," which includes a clinical algorithm to guide individualized dosing of warfarin, will improve INR control and TTR of patients in Uganda and South Africa. We will use these findings to design a larger, multisite clinical trial across several Sub-Saharan African countries.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/46710.

Warfarin pharmacogenetics in a black Zimbabwean cohort: an observational prospective study

Aim: A prospective observational study was conducted to evaluate the feasibility of implementing clinical guidelines for warfarin dosing in black Zimbabwean patients. Methods: CYP2C9*5, CYP2C9*6, CYP2C9*8 and CYP2C9*11 and VKORC1 c. 1639 G>A variations were observed in 62 study patients. Results & Conclusion: Overall, 39/62 (62.90%) participants did not receive a warfarin starting dose as would have been recommended by Clinical Pharmacogenetics Implementation Consortium guidelines. US FDA and Dutch Pharmacogenetics Working Group guidelines are based on CYP2C9*2 and CYP2C9*3 only, hence, unlikely useful in this cohort, where such variants were not detected. Clinical Pharmacogenetics Implementation Consortium guidelines, on the other hand, have a specific recommendation on the African-specific variants CYP2C9*5, CYP2C9*6 and CYP2C9*11, and are hence suitable for implementation in Zimbabwe and would help optimize warfarin doses in patients in the study cohort.

Integrating Real-World Evidence in Economic Evaluation of Oral Anticoagulants for Stroke Prevention in Non-valvular Atrial Fibrillation in a Developing Country

OBJECTIVE

This study aimed to estimate the cost effectiveness of non-vitamin K oral anticoagulants (NOACs) compared with warfarin for stroke prevention in patients with non-valvular atrial fibrillation (NVAF) in Thailand where suboptimal anticoagulation control is common.

MATERIALS AND METHODS

A hypothetical cohort of 65-year-old patients with NVAF and their disease progression was simulated in the Markov model. The following anticoagulant agents were used: warfarin, dabigatran, rivaroxaban, and apixaban. Warfarin with high, intermediate, and low time in therapeutic ranges (TTR) was used as the three different reference treatments. Baseline clinical events were obtained from a recently published real-world study in Thailand. A lifetime horizon was utilized in this model, and all analyses were performed from societal and healthcare perspectives. The results were reported as incremental cost-effectiveness ratios (ICERs) in 2021 US dollars per quality-adjusted life-year (QALY) gained. The sensitivity analyses were performed to assess the influence of parameter uncertainty.

RESULTS

Apixaban was a cost-effective intervention compared with warfarin with low and intermediate TTR groups. In the low TTR group, the ICERs were $779 and $816 per QALY gained from the societal and healthcare perspectives, respectively, and in the intermediate TTR group, the ICERs were $2038 and $3159 per QALY gained from the societal and healthcare perspectives, respectively. Both ICERs were below the accepted willingness-to-pay threshold ($4806) in the context of Thailand's healthcare.

CONCLUSIONS

In a developing country where suboptimal anticoagulation control is common, apixaban was the cost-effective alternative to warfarin for patients with both low and intermediate TTR control.

Anticoagulation control, outcomes, and associated factors in long-term-care patients receiving warfarin in Africa: a systematic review

Background

Oral anticoagulation therapy with warfarin requires frequent monitoring level of anticoagulation by the international normalized ratio (INR). In Africa, studies that explore anticoagulation control, treatment outcomes, and associated factors are reported in various ways in long-term patients receiving warfarin therapy to generate concrete scientific evidence.

Methods

The literature search was conducted in PubMed, Cochrane Library, African Journal of Online databases, Google Scholar, and Google. An advanced search strategy was computed to retrieve relevant studies related to anticoagulation control and outcomes. Duplication, title and abstract screening, and full-text assessment were conducted in Covidence software. Study quality was assessed using the Joanna Briggs Institute Critical appraisal quality assessment tool. The systematic review is registered in PROSPERO (CRD42021260772) and performed based on the Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guideline.

Results

Out of 298 identified articles, 18 articles were eligible for the final review and analysis. The mean of 39.4 ± 8.4% time in therapeutic range (TTR) (29.4 to 57.3%), 36.7 ± 11.5% TTR (range 25.2–49.7%) and 46% TTR (43.5–48.5%) was computed from studies that determined TTR by Rosendaal, direct and cross-section-of-the-files methods, respectively. In this review, the lowest percentage of TTR was 13.7%, while the highest was 57.3%. The highest percentage of patients (32.25%) who had TTR ≥ 65% was reported in Tunisia, but the lowest percentages were in Namibia (10%, TTR ≥ 65%) and Kenya (10.4%, TTR ≥ 70%). Most of the included studies (11 out of 18) used Rosendaal’s method while the direct method was employed by three studies. Generally, 10.4–32.3% of study participants achieved desired optimal anticoagulation level. Regarding secondary outcomes, 1.6–7.5% and 0.006–59% of patients experienced thromboembolic complications and bleeding events, respectively. Having chronic comorbidities, taking more than two drugs, and presence of medications that potentially interact with warfarin, and patient-related factors (patients aged < 50 years old, female gender, lower education level, smoking history) were the frequently reported predictors of poor anticoagulation therapy.

Conclusions

Oral anticoagulation control was suboptimal in patients taking warfarin as evidenced by low TTR in Africa. Therefore, there is an urgent need for further improving oral anticoagulation management services.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00416-9.

Oral anticoagulant management of patients with mechanical heart valves at the Salam Centre of Khartoum: Observations on quality of anticoagulation and thrombotic risk

INTRODUCTION

Rheumatic heart disease with mechanical heart valve (MHV) replacement is common in Africa. However, MHV requires long-life anticoagulation and managing this can be challenging.

METHODS AND RESULTS

We report data of a prospective observational study conducted between August 2018 and September 2019 in MHV patients in the Salam Centre for Cardiac Surgery built in Khartoum, by Emergency, an Italian Non-Governmental Organization, to evaluate the quality of anticoagulation control and the risk of thrombotic complications.

RESULTS

We studied 3647 patients (median age 25.1 years; 53.9 % female). Median Time in Therapeutic Range (TTR) was 53 % (interquartile range 37 % to 67 %) and 70 thrombotic events (rate 1.8 × 100 pt-years [95 % CI 1.38-2.23]) were recorded. Among patients in the first quartile of TTR (≤37 %), we recorded 34/70 (48.6 %) of all thrombotic events (rate 3.7 × 100 pt-years [95 % CI 2.5-5.1]), with a high mortality rate (2.2 × 100 pt-years [95 % CI 1.3-3.3]). In patients with guideline-recommended TTR (≥65 %) the event rate was 0.8 × 100 pt-years for thrombotic events [95 % CI 0.3-1.5] and 0.4 × 100 pt-years for mortality [95 % CI 0.1-0.9]. Multivariable analysis showed that having a TTR in the lowest quartile (≤37 %) and being noncompliant are significantly associated with increased thrombotic risk. Aspirin use or different valve type did not influence the thrombotic risk. Almost 40 % of all thromboembolic complications could have been potentially prevented by further improving VKA management to obtain a TTR > 37 %.

CONCLUSION

The thrombotic risk of MHV patients on VKAs living in a low-income country like Sudan is associated with low quality of anticoagulation control. Efforts should be made to decrease the number of non-compliant patients and to reach a guideline-recommended TTR of ≥65 %.

Assessment of knowledge and practice of cardiovascular nurses regarding warfarin

BACKGROUND

Despite new anticoagulants' developments, warfarin is still one of the most commonly used medicines, particularly in the cardiovascular system. One of the significant challenges with warfarin is the prevalence of dangerous side effects such as bleeding and drug and food interactions, which can negatively affect patients if not adequately controlled. As health-care team members, nurses have a crucial role in prescribing this medicine and educating patients. In this regard, this study was conducted to determine the knowledge and practice of nurses working in the cardiovascular wards regarding warfarin.

MATERIALS AND METHODS

In this cross-sectional, descriptive study, knowledge and practice of 239 nurses working in the cardiovascular wards of teaching hospitals affiliated to Iran University of Medical Sciences have been investigated using European Cardiovascular Nurses Knowledge questionnaire on anticoagulants and the checklist for high-risk drugs safety instructions. The sampling was performed through the stratified sampling method with proportional allocation. Data were analyzed using the SPSS software version 16 through descriptive and inferential statistics (independent t-test, one-way analysis of variance, and Pearson correlation coefficient) (Inc., Chicago, IL, USA).

RESULTS

The mean scores of knowledge (18.51 ± 3.87) and practice (10.53 ± 2.12) were slightly higher than the median, and the lowest mean score was related to knowledge on drug interactions (7.62). The practice had a statistically significant relationship with knowledge (P < 0.001). Regarding demographic variables, there was a statistically significant relationship between nurses' knowledge and the education level (P = 0.009) and nurses' practice and age (P = 0.022), work experience (P = 0.032), and work experience in cardiovascular wards (P = 0.036).

CONCLUSIONS

Based on the findings of this study, the knowledge of nurses working in the cardiovascular wards about warfarin was not sufficient, and their practice was of poor quality. Nurses' lack of knowledge and improper practice can jeopardize drug safety in patients and cause serious side effects such as bleeding. Proper training of nursing students and nurses about warfarin as a high-risk drug, its side effects, and drug-food interactions, and the emphasis on patient education in patients receiving this medicine can effectively reduce the incidence of side effects.

Economic evaluation of direct oral anticoagulants (DOACs) versus vitamin K antagonists (VKAs) for stroke prevention in patients with atrial fibrillation: a systematic review and meta-analysis

OBJECTIVES

To assess cost-effectiveness of direct oral anticoagulants (DOACs) compared with vitamin K antagonists (VKAs) for stroke prevention in atrial fibrillation (AF) by pooling incremental net benefits (INBs).

DESIGN

Systematic review and meta-analysis.

SETTING

We searched PubMed, Scopus and Centre for Evaluation of Value and Risks in Health Registry from inception to December 2019.

PARTICIPANTS

Patients with AF.

MAIN OUTCOME MEASURES

The INB was defined as a difference of incremental effectiveness multiplied by willing to pay threshold minus the incremental cost; a positive INB indicated favour treatment. These INBs were pooled (stratified by level of country income, perspective, time-horizon, model types) with a random-effects model if heterogeneity existed, otherwise a fixed effects model was applied. Heterogeneity was assessed using Q test and I² statistic. Risk of bias was assessed using the economic evaluations bias (ECOBIAS) checklist.

RESULTS

A total of 100 eligible economic evaluation studies (224 comparisons) were included. For high-income countries (HICs) from a third-party payer (TPP) perspective, the pooled INBs for DOAC versus VKA pairs were significantly cost-effective with INBs (95% CI) of $6632 ($2961.67 to $10 303.72; I²=59.9%), $6353.24 ($4076.03 to $8630.45; I²=0%), $7664.58 ($2979.79 to $12 349.37; I²=0%) and $8573.07 ($1877.05 to $15 269.09; I²=0%) for dabigatran, apixaban, rivaroxaban and edoxaban relative to VKA, respectively but only dabigatran was significantly cost-effective from societal perspective (SP) with an INB of $11 746.96 ($2429.34 to $21 064.59; I²=52.4%). The pooled INBs of all comparisons for upper-middle income countries (UMICs) were not significantly cost-effective. The ECOBIAS checklist indicated that risk of bias was mostly low for most items with the exception of five items which should be less influenced on pooling INBs.

CONCLUSIONS

Our meta-analysis provides comprehensive economic evidence that allows policy makers to generalise cost-effectiveness data to their local context. All DOACs may be cost-effective compared with VKA in HICs with TPP perspective. The pooling results produced moderate to high heterogeneity particularly in UMICs. Further studies are required to inform UMICs with SP.

PROSPERO REGISTERATION NUMBER

CRD 42019146610.

[Time in therapeutic range and incidence of warfarin complications in a 20-year retrospective cohort]

Objetivo

Caracterizar el tiempo en rango terapéutico (TTR) y estimar la tasa de incidencia de complicaciones (PTIRc) en adultos con protocolo de warfarina.

Diseño

Cohorte retrospectiva basada en registros médicos de pacientes mayores de 18 años entre 1996 a 2016 y seguidos al menos tres meses.

Emplazamiento

Unidad de Hematología de un centro especializado cardiovascular venezolano.

Participantes

Registros médicos electrónicos.

Mediciones principales

TTR y PTIRc. Las variables fueron: sexo, analfabetismo funcional, ocupación, international normalized ratio (INR) y tiempo de seguimiento, que fueron analizados con TTR and PTIRc mediante modelos de logística binomial y regresión de Poisson, respectivamente.

Resultados

Un total de 2.770 pacientes fueron seguidos durante 1.201.380 días; el 42,3% tuvieron un TTR < 65% y el 3,5% tuvieron indicación de INR 2,5-3,5. El 61,8% presentaron complicaciones. La PTIRc fue de 6,84/100 personas-mes (IC 95%: 6,56-7,15). TTR < 65% mostró OR ajustadas significativas con analfabetismo funcional e INR 2,5-3,5, mientras que para la mayor PTIRc se encontró un RR significativo en los dos factores mencionados, menor tiempo de seguimiento, TTR < 65% y en mujeres.

Conclusiones

A pesar de nuevos tratamientos anticoagulantes, la warfarina es útil. A medida que aumentó el tiempo de seguimiento el control fue mejor y la velocidad de aparición de complicaciones disminuyó; sin embargo, las condiciones que mostraron menor TTR y mayor velocidad de aparición de complicaciones requieren una profunda revisión del seguimiento, de manera especial en pacientes con analfabetismo funcional.

Relationship Amongst Vitamin K Status, Vitamin K Antagonist Use and Osteoarthritis: A Review

Vitamin K is essential for the carboxylation of the vitamin K-dependent proteins that are responsible for the suppression of matrix calcification. The use of vitamin K antagonists (VKAs) in patients with cardiovascular diseases could affect protein carboxylation and lead to the development of osteoarthritis (OA). This review aims to summarise the current evidence for the relationship between VKAs and OA. The literature search revealed that in observation studies, good vitamin K status, as reflected by the circulating level or protein carboxylation status of vitamin K, is associated positively with improved joint structural and functional indices and negatively associated with OA incidence. By contrast, in limited retrospective and prospective studies, the use of VKAs is associated positively with OA occurrence and knee/hip replacement. Pharmacological interactions between VKAs and various OA therapeutic agents exist and require careful monitoring and dosing. In conclusion, further epidemiological studies are warranted to verify the relationship between VKA use and OA to strengthen the evidence. Given that VKA use exerts potentially negative effects on joint health, intervention is required to protect the quality of life and mobility of patients.

Prevalence and factors associated with psychological distress among patients on warfarin at the Uganda Heart Institute, Mulago Hospital

INTRODUCTION

Cardiovascular diseases (CVD) are the leading cause of mortality worldwide and are significantly associated with multiple comorbid disorders including mental disorders such as psychological distress (PD). At increased risk of PD are CVD patient sub-categories that not only require chronic therapy but also need follow up with continuous blood tests and dose adjustments (like the patients on warfarin). However, not much has been done to ascertain the burden of PD among patients on warfarin in Uganda.

OBJECTIVE

To determine the prevalence and factors associated with PD among patients on anticoagulation with warfarin at the Uganda Heart Institute (UHI).

METHODS

In this analytical cross-sectional study, 197 participants were sampled from adults on warfarin attending the Uganda Heart Institute (UHI) out patient clinic. The Self Reporting Questionnaire (SRQ-20), a tool with a total maximum score of 20 and cutoff for PD at ≥6 was used to determine the presence of PD among participants, and a socio-demographic questionnaire to document the socio-demographic characteristics of the subjects. Additional questions including the underlying CVD diagnosis, medications used (besides warfarin) and presence of chronic illnesess were also assessed. Bi-variable and multi-variabe logistic regression analysis techniques were used to examine the associations between the dependent and independent variables.

RESULTS

The prevalence of PD was 32%. The unemployed participants were 4.5 times more likely to have PD (adjusted odds ratio [aOR]4.56, 95% confidence interval [CI]: 1.12-18.62, p = 0.04). Participants who had experienced social stressors were more likely to have PD (aOR: 11.38, CI: 3.60-36.04, p < 0.01). Other factors associated with a higher likelihood of having PD included: presence of other chronic comorbidities (aOR: 3.69, CI: 1.24-11.02, p = 0.02) and concomitant use of loop diuretics (aOR: 4.13, CI: 1.67-10.19,p < 0.01). A shorter length of time on warfarin (7-24 months) lowered the likelihood of PD (aOR: 0.23, CI: 0.07-0.74, p = 0.01).

CONCLUSION

The prevalence of PD was high among patients on warfarin in this low income setting and there is a need to characterize the specific psychiatric disorders in patients with CVD. Interventions that address the high burden of PD are urgently needed in this setting.

Ethnic Diversity and Warfarin Pharmacogenomics

Warfarin has remained the most commonly prescribed vitamin K oral anticoagulant worldwide since its approval in 1954. Dosing challenges including having a narrow therapeutic window and a wide interpatient variability in dosing requirements have contributed to making it the most studied drug in terms of genotype-phenotype relationships. However, most of these studies have been conducted in Whites or Asians which means the current pharmacogenomics evidence-base does not reflect ethnic diversity. Due to differences in minor allele frequencies of key genetic variants, studies conducted in Whites/Asians may not be applicable to underrepresented populations such as Blacks, Hispanics/Latinos, American Indians/Alaska Natives and Native Hawaiians/other Pacific Islanders. This may exacerbate health inequalities when Whites/Asians have better anticoagulation profiles due to the existence of validated pharmacogenomic dosing algorithms which fail to perform similarly in the underrepresented populations. To examine the extent to which individual races/ethnicities are represented in the existing body of pharmacogenomic evidence, we review evidence pertaining to published pharmacogenomic dosing algorithms, including clinical utility studies, cost-effectiveness studies and clinical implementation guidelines that have been published in the warfarin field.

Micro-mechanical blood clot testing using smartphones

Frequent prothrombin time (PT) and international normalized ratio (INR) testing is critical for millions of people on lifelong anticoagulation with warfarin. Currently, testing is performed in hospital laboratories or with expensive point-of-care devices limiting the ability to test frequently and affordably. We report a proof-of-concept PT/INR testing system that uses the vibration motor and camera on smartphones to track micro-mechanical movements of a copper particle. The smartphone system computed the PT/INR with inter-class correlation coefficients of 0.963 and 0.966, compared to a clinical-grade coagulation analyzer for 140 plasma samples and demonstrated similar results for 80 whole blood samples using a single drop of blood (10 μl). When tested with 79 blood samples with coagulopathic conditions, the smartphone system demonstrated a correlation of 0.974 for both PT/INR. Given the ubiquity of smartphones in the global setting, this proof-of-concept technology may provide affordable and effective PT and INR testing in low-resource environments.

Therapy with anticoagulants requires frequent monitoring. Here the authors describe a proof-of-concept study of a simple and affordable blood clot test that uses a smartphone’s vibration motor and camera to track micro-movements in a single drop of blood.

Vitamin K-dependent anticoagulant use and level of anticoagulation control in sub-Saharan Africa: protocol for a retrospective cohort study

BACKGROUND

Given that vitamin K-dependent anticoagulants (VKAs) will continue to be the primary anticoagulant in Africa for a long time, understanding the quality of anticoagulation services in the continent is vital for optimising the intended benefits. Notably, a few small studies have assessed the quality of anticoagulation in sub-Saharan Africa (SSA) countries. This study will describe the current VKA use and anticoagulation control among patients in selected SSA countries.

METHODS AND ANALYSIS

We plan to review the 2019 anticoagulation data of a cohort of 800 random patients from 19 selected clinics in Botswana, the Democratic Republic of Congo, Ethiopia, Gambia, Ghana, Mozambique, Nigeria, Tanzania and South Africa. We expect at least one participating site to enrol 100 participants in each country. Eligible participants will be those on VKAs for at least 3 months and with at least four international normalised ratio (INR) results. We will document the indications, type and duration of VKA use, sociodemographic factors, coexisting medical conditions, concurrent use of drugs that interact with warfarin and alcohol and tobacco products. The level of anticoagulation control will be determined by calculating the time-in-therapeutic range (TTR) using the Rosendaal and the Percent of INR in TTR methods. A TTR of less than 65% will define a suboptimal anticoagulation control.

ETHICS AND DISSEMINATION

This study was approved by the Ministry of Health and Wellness Ethics Committee (HPDME13/8/1) in Botswana and local research ethics committees or institutional review boards of all participating sites. As the study collects data from existing records, sites applied for waivers of consent. We will disseminate research findings through peer-reviewed scientific publications.

Evaluation of patients' knowledge of warfarin at Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia

Objective

The study was to assess the knowledge of warfarin in patients using the validated anticoagulation knowledge assessment questionnaire and to evaluate the predictors of the level of knowledge among outpatients receiving warfarin at the Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia.

Methods

It was a prospective cross-sectional study carried out from October 2019–January 2020. During the study period a total 401 of them were included in the study. Anticoagulation Knowledge Assessment questionnaire has 29 question items, a single patient should answer at least 21 of the question to be considered as knowledgeable about his/her medication. The data was exported into SPSS version 25 and a one way ANOVA and post hoc were conducted.

Results

The mean age of the study participants were 36 years old (SD ± 11.83), which was ranges from 18 to 82 and majority of the participants were females (69.6%). Almost in one-third of the participants (35.7%), the reasons for warfarin therapy were Chronic Rheumatic Valvular Heart Disease. The overall AKA mean ± SD score of the respondents was 7.4 (±2.6) that ranges from 2 to 22. From those only (4.2%) of the study participants had succeeds the passing score. Educational level and the duration of warfarin therapy were independent predictors towards patient’s warfarin knowledge.

Conclusion

The overall patient’s knowledge about warfarin treatment was poor when it was compared to most other studies. The longer duration of warfarin therapy and advanced educational level showed favored relationship towards better warfarin knowledge of the study participants.

Screening for Atrial Fibrillation in Sub-Saharan Africa: A Health Economic Evaluation to Assess the Feasibility in Nigeria

Background:

Cardiovascular disease reflects a major burden of non-communicable disease in Sub-Saharan Africa (SSA). Early detection and treatment of atrial fibrillation (AF), as a preventive measure against stroke, is currently not in the scope of the World Health Organization recommendation to reduce cardiovascular disease.

Objective:

We hypothesized that screening for AF would be an important approach to determine the true AF prevalence in the general population in African countries and to identify asymptomatic AF patients at risk for stroke to optimize prevention.

Methods:

A decision analytic model was developed to study the health-economic impact of AF screening in Nigeria over a life-time horizon. The patient population explored in the model was a population of newly detected AF cases that would be diagnosed with a one-time systematic screening for AF with a single lead ECG device in community health centres across Nigeria.

Conclusions:

The health gain per newly detected AF patient (N = 31,687) was 0.41 QALY at a cost of $5,205 per patient with 100% NOAC use, leading to an ICER of $12,587 per QALY gained. The intervention was cost-effective with a 99.9% warfarin use with an ICER of $1,363 per QALY gained. The total cost of a single screening session was $7.3 million for the total screened population in Nigeria or $1.60 per patient screened. Screening for AF to detect AF patients in need for stroke prevention can be a cost-effective intervention in the Sub-Saharan region, depending on type of anticoagulant used and drug costs.

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

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 international normalised ratio monitoring, the lack of locally validated standardized dosing protocols, and low levels of anticoagulation knowledge among healthcare workers and patients. Increasing numbers of patients will need anticoagulation in the future because of the increasing burden of noncommunicable disease 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.

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

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.

Developing and Validating a Clinical Warfarin Dose-Initiation Model for Black-African Patients in South Africa and Uganda

Warfarin remains the oral anticoagulant of choice in sub-Saharan Africa. However, dosing is challenging due to a highly variable clinical response for a given dose. This study aimed to develop and validate a clinical warfarin dose-initiation model in sub-Saharan Black-African patients. For the development cohort, we used data from 364 patients who were recruited from 8 outpatient clinics and hospital departments in Uganda and South Africa (June 2018-July 2019). Validation was undertaken using the International Warfarin Pharmacogenetics Consortium (IWPC) dataset (690 black patients). Four predictors (age, weight, target International Normalized Ratio range, and HIV status) were included in the final model, which achieved mean absolute errors (MAEs; mean of absolute differences between true dose and dose predicted by the model) of 11.6 (95% confidence interval (CI) 10.4-12.8) and 12.5 (95% CI 11.6-13.4) mg/week in the development and validation cohorts, respectively. Two other clinical models, IWPC and Gage, respectively, obtained MAEs of 12.5 (95% CI 11.3-13.7) and 12.7 (95% CI 11.5-13.8) mg/week in the development cohort, and 12.1 (95% CI 11.2-13.0) and 12.2 (95% CI 11.4-13.1) mg/week in the validation cohort. Compared with fixed dose-initiation, our model decreased the percentage of patients at high risk of suboptimal anticoagulation by 7.5% (1.5-13.7%) and 11.9% (7.1-16.8%) in the development and validation cohorts, respectively. The clinical utility of this model will be tested in a prospective study. Study Highlights WHAT IS THE CURRENT KNOWLEDGE ON THE TOPIC? ☑ Warfarin dosing remains challenging due to a highly variable clinical response for a given dose. WHAT QUESTION DID THIS STUDY ADDRESS? ☑ Can a clinical dose-initiation model be developed and validated for sub-Saharan Black-African patients? WHAT DOES THIS STUDY ADD TO OUR KNOWLEDGE? ☑ We have developed the first warfarin dose-initiation clinical model for Black-African patients in Uganda and South Africa. HOW MIGHT THIS CHANGE CLINICAL PHARMACOLOGY OR TRANSLATIONAL SCIENCE? ☑ We will be implementing and validating this model in a prospective cohort to inform future large-scale implementation. More optimized dosing should improve the quality of warfarin anticoagulation in these two developing countries.

Evaluation of Stable Doses of Warfarin in a Patient Cohort

BACKGROUND

Definitions for stable dose of warfarin varies in the reported studies. International warfarin pharmacogenetic consortium (IWPC) algorithm was generated from the data based on these definitions.

OBJECTIVE

In the present study, we primarily evaluated whether any significant differences exist between the definitions for stable warfarin dose.

METHODS

A prospective cross-sectional study in adults receiving warfarin for at least 3 months was carried out. Stable doses of warfarin as defined in previous studies were compared with the standard definition. Bland-Altman plots, Pearson's correlation and intra-class coefficients (ICC) were used to assess the correlation, reliability and agreements between the doses.

RESULTS

Sixty-four patients were recruited. Twenty definitions were obtained from the previous studies. We observed that all but one showed very high or high positive correlations; and either excellent or good ICC. No significant differences between the doses initiated and predicted by IWPC algorithm.

CONCLUSION

We observed similar stable doses between the definitions except for one. Hence, IWPC algorithm may not have any bias associated with inclusion of any studies with variable definitions for stable warfarin dose.