Quality of anticoagulation with warfarin in rural Chhattisgarh, India

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.

Left Atrial Diameter in the Prediction of Thromboembolic Event and Death in Atrial Fibrillation

Background: This study aimed to determine the predictive value of left atrial diameter (LAD), and the incremental prognostic value of LAD in combination with CHA2DS2-VASc score for predicting thromboembolic event and all-cause death in patients with non-valvular atrial fibrillation (AF). Methods: This is a prospective study from 27 hospitals during 2014−2017. LADi is LAD data indexed by body surface area, and LADi in the 4th quartile (LADi Q4) was considered high. Results: A total of 2251 patients (mean age 67.4 years, 58.6% male) were enrolled. Mean follow-up duration was 32.3 months. Rates of thromboembolic events and all-cause death were significantly higher in LADi Q4 patients than in LADi Q1−3 patients (2.89 vs. 1.11 per 100 person-years, p < 0.001, and 7.52 vs. 3.13 per 100 person-years, p < 0.001, respectively). LADi Q4 is an independent predictor of thromboembolic events and all-cause death with an adjusted hazard ratio and 95% confidence interval of 1.94 (1.24−3.05) and 1.81 (1.38−2.37), respectively. LADi has incremental prognostic value on top of the CHA2DS2-VASc score with the increase in global chi-square for thromboembolism (p = 0.005) and all-cause death (p < 0.001). Conclusions: LADi is an independent predictor of thromboembolic event and has incremental prognostic value in combination with CHA2DS2-VASc score in AF patients.

Development of an interview-based warfarin nomogram predicting the time spent in the therapeutic INR range: a cost-effective, and non-invasive strategy building from a cross sectional study in a low resource setting

A cross-sectional study was conducted to predict time in therapeutic range (TTR) using clinical history, examination, and socioeconomic data. Study included warfarin-receiving patients from outpatient-clinic. In 203 patients studied, mean warfarin start-dose was 2.55 mg/day and maintenance-dose/week was 30.79 mg. Body mass index (BMI) (p = 0.03), warfarin maintenance dose/day (p = 0.02), and comorbidity presence (p = 0.04) were significantly associated with TTR. Occupation (p = 0.53), income (p = 0.83), education (p = 0.55), and socioeconomic score (p = 0.73) showed non-significant association with TTR. A TTR predicting nomogram was built from clinical history and examination findings.

Development and validation of a mobile application based on a machine learning model to aid in predicting dosage of vitamin K antagonists among Indian patients post mechanical heart valve replacement

Patients who undergo heart valve replacements with mechanical valves need to take Vitamin K Antagonists (VKA) drugs (Warfarin, Nicoumalone) which has got a very narrow therapeutic range and needs very close monitoring using PT-INR. Accessibility to physicians to titrate drugs doses is a major problem in low-middle income countries (LMIC) like India. Our work was aimed at predicting the maintenance dosage of these drugs, using the de-identified medical data collected from patients attending an INR Clinic in South India. We used artificial intelligence (AI) - machine learning to develop the algorithm. A Support Vector Machine (SVM) regression model was built to predict the maintenance dosage of warfarin, who have stable INR values between 2.0 and 4.0. We developed a simple user friendly android mobile application for patients to use the algorithm to predict the doses. The algorithm generated drug doses in 1100 patients were compared to cardiologist prescribed doses and found to have an excellent correlation.

Long-term oral anticoagulation for atrial fibrillation in low and middle income countries

With increasing life-expectancy and changing demographics, non-valvular atrial fibrillation (AF) is currently the most common indication for long-term oral anticoagulation (OAC) in low and middle income countries (LMICs). Due to a decreasing trend in the prevalence of rheumatic heart disease (RHD), valve disease as a primary cause of AF now constitutes a small fraction of all people with AF. Moreover, emerging data also indicate that, patients with significant valve disease and AF may have a risk of stroke similar to, if not lower than, those with non-valvular AF. Previous trials of anticoagulation for AF excluded people from LMICs partly because valvular AF constituted a large proportion of those with AF, and it was thought to confer a prohibitively high risk of stroke. Trialists should therefore be less reluctant to include patients with AF from LMICs in general, and those with valve disease in particular, in future trials of anticoagulation. The quality of vitamin K antagonist based oral anticoagulation remains poor in LMICs to a large extent because of poor monitoring. The widespread use of the direct oral anticoagulants (DOAC) presents a practical approach to improve anticoagulation quality. Randomised trials of DOACs in valvular AF are particularlycriticalto bridge the knowledge gap in this area.

Discussions regarding oral anticoagulation (OAC) use in low and middle income countries (LMICs) have historicallybeendominated by severallong-held beliefs. The first is that the quality of vitamin K antagonist (VKA) based anticoagulation is poor in these countries. The veracity of this assumption is supported by a large number of studies documenting both lower prescription of OACs, and a lower proportion of international normalised ratio (INR) values in the therapeutic range.¹The second is that a large proportion of patients receiving OAC in LMICs have atrial fibrillation (AF) related to valvular heart disease, and rheumatic mitral stenosis in particular. This assumption, perhaps valid several decades ago, is no longer supported by the data. Finally, patients with valvular heart disease and AF (specifically those with moderate or severe valve lesions), are thought to be at prohibitively high thromboembolic risk. ² However, recent evidence suggests that this risk may have been overestimated.³⁴Nevertheless, the aforementioned assumptions continue to contribute to the underrepresentation of patients from LMICs in clinical trials of oral anticoagulation. Knowledge of the characteristics of contemporary patients in LMICs who are eligible for long-term OAC, estimates of their stroke risk, and a better understanding of the drivers of poor anticoagulation quality, may help guide research and clinical practice. In this review, we seek to provide an evidence-based perspective on OAC use in patients with AF living in LMICs and China.