A Prospective Observational Study of Coagulation Profiles in Patients on Common Antithrombotic Therapies and Their Correlation with Bleeding Risk

ABSTRACT:

Antithrombotic therapies including warfarin and antiplatelet agents require careful monitoring to balance thrombotic protection against bleeding risk. This is particularly challenging in resource-limited settings where access to specialized coagulation testing is often restricted. A prospective observational study was conducted from January to December 2023 at three tertiary care hospitals in Nigeria. We enrolled 450 patients on stable antithrombotic therapy (150 on warfarin, 150 on aspirin, 150 on clopidogrel) and followed them for six months. Prothrombin time/international normalized ratio (PT/INR), activated partial thromboplastin time (aPTT), and bleeding events were monitored monthly. Among warfarin patients, only 42.7% maintained therapeutic INR ranges (2.0-3.0) across all measurements, while 34.0% showed subtherapeutic and 23.3% supratherapeutic values. The incidence of major bleeding was significantly higher in patients with INR >3.5 (18.9% vs. 2.3% in therapeutic range, p<0.001). Antiplatelet therapy patients demonstrated minimal changes in conventional coagulation parameters despite clinically significant bleeding events. Multivariate analysis identified age >65 years (OR: 3.2, 95% CI: 1.8-5.7), renal impairment (OR: 2.8, 95% CI: 1.5-5.2), and concomitant NSAID use (OR: 2.4, 95% CI: 1.3-4.4) as independent predictors of bleeding Basic coagulation tests effectively stratify bleeding risk in warfarin-treated patients but have limited utility for monitoring antiplatelet therapies. Simplified risk assessment tools incorporating clinical factors and basic laboratory parameters can optimize antithrombotic management in settings with limited resources.

Keywords: Antithrombotic, Antiplatelet agents, Bleeding risk, Coagulation profiles, INR monitoring, Resource-limited settings, Warfarin