Background: Warfarin has a narrow therapeutic index with INR values between 2.0 - 3.0. According to our clinical experience, control of INR levels during hospitalization is poor.
Objectives: The study aimed to evaluate control of INR levels during hospitalization in the departments of internal medicine, to determine the factors that influence INR levels during hospitalization, and the association between the control of INR levels before and during hospitalization.
Methods: This is a retrospective study, including the data of patients who were admitted to the internal medicine wards at Meir and Rabin Medical Centers, Israel, between May 2011 and May 2013. Inclusion criteria: patients who were treated with warfarin prior and during the index hospitalization and at least 3 INR tests were taken during the hospitalization and the 3 months before it. The collected data included: demographic parameters (age, gender), medical background, cause of admission, relevant medications for INR control, duration of hospitalization and INR values. The INR control during hospitalization and the previous 3 months, the parameters that affect INR levels and the association between control before and during hospitalization were evaluated.
Results: Of 1861 screened patients, only 299 filled the inclusion criteria. Among those patients, 93 (31%) were considered to have well controlled INR rates during the hospitalization. No significant differences were found between the controlled and uncontrolled groups. The risk of a well-controlled patient before admission to be uncontrolled during admission was 63%, whereas the risk of an uncontrolled patient before admission to remain uncontrolled during hospitalization was 73%.
Conclusions: By using a larger study group it might be possible to achieve significant results and to set guidelines for INR control during admission.
Discussion: Most patients are not monitored well enough to estimate their degree of INR control. Most of the patients, who could be evaluated, were uncontrolled.