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Published on: February 26, 2013
Anticoagulation control for nonvalvular atrial fibrillation in a tertiary academic centre in Johannesburg
Vanessa Mogashoa1, Dineo Mpanya1, Nqoba Tsabedze2
1Division of Cardiology, Department of Internal Medicine, School of Clinical Medicine, Faculty of Health Sciences, University of the Witwatersrand, 17 Jubilee Road, Johannesburg, 2193, Gauteng Province, South Africa.
Insights
Optimal anticoagulation control (TTR ≥ 70%) was achieved in only 35.6% of non-valvular atrial fibrillation patients on warfarin in Johannesburg. This highlights challenges in managing atrial fibrillation anticoagulation in this setting.
Area of Science:
- Cardiology
- Pharmacology
- Public Health
Background:
- Atrial fibrillation is a growing health concern in Africa.
- Warfarin is the primary anticoagulant in low- and middle-income countries for non-valvular atrial fibrillation (NVAF).
- Maintaining time in therapeutic range (TTR) on warfarin is crucial for preventing complications.
Purpose of the Study:
- To assess anticoagulation control in NVAF patients on warfarin.
- To determine the proportion of patients achieving optimal TTR.
- To identify factors associated with anticoagulation control.
Main Methods:
- A cross-sectional retrospective study was conducted in Johannesburg, South Africa.
- Data from NVAF patients treated between 2015 and 2019 were analyzed.
- Time in therapeutic range (TTR) was calculated using the Rosendaal method.
Main Results:
- Only 35.6% of 177 NVAF patients achieved an optimal TTR (≥ 70%).
- Patients with poor anticoagulation control had shorter warfarin treatment durations (p=0.0013).
- Warfarin toxicity was observed in 7.3% of patients.
Conclusions:
- Optimal anticoagulation control on warfarin is suboptimal in this South African cohort.
- Further strategies are needed to improve TTR and patient outcomes in NVAF management.
- The study underscores the challenges of anticoagulation therapy in resource-limited settings.
Background:
Atrial fibrillation is a growing epidemic in Africa. Anticoagulation, considered the backbone for non-valvular atrial fibrillation (NVAF) management, is limited to warfarin as the mainstay of available anticoagulation therapy in most low- and middle-income countries (LMIC). The optimal time in the therapeutic range (TTR) while on warfarin is essential to avoid bleeding and thromboembolic complications. This study assessed anticoagulation control in patients with NVAF on warfarin in Johannesburg, South Africa.
Methods:
We conducted a cross-sectional retrospective study on patients with NVAF managed in the Division of Cardiology, at a tertiary-level academic centre in Johannesburg, South Africa, between 1 January 2015 and 31 December 2019. Anticoagulation control for patients with NVAF was assessed by calculating the TTR using the Rosendaal method.
Results:
The study population comprised 177 patients diagnosed with NVAF. The mean age was 65.0 ± 13.1 years. The median TTR among patients with NVAF was 46% [interquartile range (IQR): 8.7-86.0], and 63 (35.6%) patients with NVAF had a TTR ≥ 70% (optimal anticoagulation control). Patients with poor anticoagulation control (TTR < 70%) were on warfarin for a shorter duration compared with those with optimal anticoagulation control [56 days (IQR: 43-84) vs. 70 days (IQR: 56-140), p = 0.0013]. The mean CHA2DS2-VASc score was 4 ± 1.5, and it did not differ between patients with poor or optimal anticoagulation control. Among the 175 patients with available HAS-BLED scores, 21 (12.0%), 112 (64.0%) and 42 (24.0%) were at a low, moderate, and high risk for bleeding, respectively. Of the 21 patients in the HAS BLED low-risk category, only 4 (19.0%) had a TTR < 70% (p < 0.001). Warfarin toxicity was documented in 13 (7.3%) patients.
Conclusion:
In our study, a TTR ≥ 70%, suggesting optimal anticoagulation control, was found in only 35.6% of patients with NVAF on warfarin.
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