Anticoagulation quality through time in therapeutic range in Sub-Saharan Africa: a systematic review and meta-analysis

Background: The quality of anticoagulation with warfarin is often assessed through the time in therapeutic range (TTR). However, achieving optimal TTR and maintaining therapeutic INR levels presents significant challenges in Sub-Saharan Africa. This review aims to summarize the existing evidence on the quality of warfarin anticoagulation among patients in Sub-Saharan Africa.

Method: We searched MEDLINE via Ovid, PubMed, Embase via Ovid, and Scopus, and citation analysis from Google Scholar. The review’s primary focus was therapeutic INR and TTR ≥ 65. Meta-analysis was conducted using R version 4.3.3. A mixed-effects meta-regression model was used to examine the influence of moderators, with heterogeneity estimated using I2 and prediction intervals (PI), and publication bias assessed through funnel plots and Egger’s test, with p < 0.05 indicating potential bias. The robustness of pooled proportions was tested using a leave-one-out sensitivity analysis. The preparation of this review adhered to the guidelines outlined in the PRISMA.

Results: We identified 15 observational studies for inclusion in this systematic review and meta-analysis. Egger’s test confirmed an absence of publication bias across these studies. Sensitivity analyses showed consistency in individual therapeutic INR (pooled estimate: 0.37; range: 0.37–0.40) and TTR (pooled estimate: 0.16; range: 0.15–0.17), closely aligning with pooled proportions. Meta-analysis of high-quality TTR measurements yielded a pooled prevalence of 17% (I2 = 89%), with study-specific values ranging from 10 to 29% and predicted effect sizes between 0.05 and 0.34. The therapeutic INR was observed at a pooled prevalence of 40% (I2 = 86%; prediction interval: 0.16, 0.67).

Conclusion: Warfarin therapy is associated with very low percentage of TTR suggests poor quality of anticoagulation management. Sensitivity analyses confirmed the robustness of these findings.