Identifying Potential Predictors of High-Quality Oral Anticoagulation Assessed by Time in Therapeutic International Normalized Ratio Range: A Prospective, Long-Term, Single-Center, Observational Study

Abstract Background The efficacy and risks of oral anticoagulation are largely associated with maintaining the quality of anticoagulation control. Nevertheless, few studies have addressed which factors, if any, are associated with this control. Objective This study aimed to identify predictors of high-quality oral anticoagulation. Methods A prospective observational study enrolled all adult patients on intended long-term oral anticoagulation attending a public anticoagulation clinic. Patients with high-quality anticoagulation, defined as percentage of time in therapeutic international normalized ratio (INR) range (TTR) ≥66%, were compared with those with poor anticoagulation control (TTR Results Participation was requested from all 233 patients followed up at the anticoagulation clinic. Eighty-six did not meet the inclusion criteria (49 due to intended anticoagulation duration 2 months (OR = 3.23; 95% CI, 1.25–8.36); presence of family support (OR = 3.32; 95% CI, 1.16–9.48); functional and cognitive ability to take medications as prescribed, defined as good medication management capacity (MMC; as assed using the Drug Regimen Unassisted Grading Scale) (OR = 4.18; 95% CI, 1.63–10.68); and no regular use of alcohol (OR = 8.59; 95% CI, 1.45–51.09). Conclusions The data suggest that independent predictors of high-quality oral anticoagulation included regular vitamin K intake, male sex, duration of anticoagulation treatment >2 months, presence of family support, good MMC, and no regular alcohol use. These findings may help clinicians to decide whether to start anticoagulation in intermediate-risk patients, to identify patients who will require closer attention on their anticoagulation management, and to direct their efforts to improve the quality of oral anticoagulation.