Influence of Clinical Risk Factors on International Normalized Ratio Control in Patients on Warfarin Therapy: A Systematic Review

Warfarin remains a widely prescribed oral anticoagulant despite its narrow therapeutic index and its association with life-threatening bleeding events.This systematic review examined the impact of clinical risk factors on international normalized ratio (INR) control in patients receiving Warfarin therapy.Following the PRISMA-P guidelines, we searched four electronic databases (PubMed, SCOPUS, Embase, and Web of Science) using Medical Subject Headings to identify eligible cohort studies published between 2016 and 2020.A total of 15 original research articles met the inclusion criteria.The risk of bias was assessed using the Newcastle-Ottawa scale.This review identified several clinical risk factors influencing INR control, including drug interactions with Warfarin, herbal supplements, dietary intake of vitamin K, and multiple comorbidities (anemia, heart failure, chronic kidney disease, psychiatric disorders, prosthetic valve), kidney transplant recipient, hemodialysis, and hypoalbuminemia.These clinical risk factors adversely affect the time in therapeutic range, thereby increasing the risk of adverse outcomes such as thromboembolism, major bleeding, and mortality.Overall, these clinical risk factors compromise Warfarin efficacy by contributing to subtherapeutic or supratherapeutic INR levels.Identifying and addressing these clinical risk factors prior to initiating Warfarin therapy is essential to achieving optimal INR control.