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

ABSTRACT

Background: Oral anticoagulation therapy with warfarin requires frequent monitoring level of anticoagulation by the international normalized ratio (INR). Aim(s) Therefore, this systematic review aimed to systematically summarize anticoagulation control, treatment outcomes, and associated factors in long-term patients receiving warfarin in Africa. Method(s) 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 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 PRISMA guideline. Result(s) 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. The lowest percentage of TTR was 13.7%, while the highest was 57.3% was observed in this review. 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%). 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. The presence of chronic comorbidities, taking more than two drugs, and presence of medications that potentially interact with warfarin was the frequently reported predictors of poor anticoagulation therapy. Conclusion(s) 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 service.