Time in Therapeutic Range of Oral Vitamin K Antagonists in Hospitalized Elderly Patients

Oral vitamin K antagonists (VKAs) are commonly used in older adults. To ensure the efficiency and safety of these drugs, the international normalized ratio (INR) must be monitored. The time in therapeutic range (TTR) is an internationally recommended assessment of the anticoagulation quality.

Our study aimed to assess the TTR of VKAs in a hospitalized geriatric population and identify factors associated with low TTR.

This was a multicenter retrospective study of data from 1899 patients with a mean age of 87 years between 2013 and 2015 in the geriatric units of four French hospitals. The data collection consisted of 2450 VKA prescriptions. We excluded prescriptions with a duration of < 7 days, monitoring with fewer than two INR values and patients with prosthetic heart valves. TTR was assessed using the Rosendaal method. Factors associated with a low TTR (< 50%) were assessed using a non-parametric method.

The mean TTR observed in this population was 42.6%. The TTR was < 50% for 62.5% of the patients included in this study. Significant associations were found between TTR < 50% and aspartate transaminase (AST), alkaline phosphatase (ALT), thyroid-stimulating hormone (TSH), prescription duration, fluconazole instauration, hemoglobin, and C-reactive protein (CRP).

Both our results and those in the literature indicate that TTR in geriatric populations is lower than that in the general population. Most patients had an insufficient TTR, exposing them to an increased risk of thromboembolic and hemorrhagic events. These data provide a perspective on poor-quality anticoagulation and illustrates the difficulty of using VKAs in geriatric patients.