Abstract:
Background: Warfarin is a highly effective therapy to prevent thromboembolic complications of
venous thromboembolism (VTE), atrial fibrillation (AF), cardiac thrombus and valvular heart
disease. While its optimum effect is achieved when international normalized ratio (INR) is in
target, Sub therapeutic level increases both the risk and severity of thromboembolism. Despite
thrombotic consequences of Sub therapeutic INR, little is known about its prevalence.
Objective: This study assessed the proportion and factor associated with Sub therapeutic INR
among patients on warfarin at Jimma medical center (JMC).
Method- Institution based prospective Cross-sectional study was done from October 1, 2021-
December 30, 2021 among 196 patients on warfarin following chronic follow up at Jimma
Medical Center. The collected data was entered into a computer by EpiData software version 3.1
and analyzed using statistical package for the social sciences (SPSS) software version 25. A
descriptive statistics was used to describe categorical variables as frequencies and percentages
while continuous data was described using mean, median, standard deviation. Binary and
multivariate logistic regression was used to identify statistical significance at p value of <0.05.
Result: The Majority (84.7%) of the respondents has Time in therapeutic range (TTR) below
sixty percent. In this study, poor adherence to warfarin, presence of comorbidity and shorter
duration of warfarin were significantly associated with sub therapeutic INR at P-value less than
0.05. Additionally, the independent predictors of sub-therapeutic INR were non adherence to
warfarin (AOR 6.13 (95% CI ((3.31-28.10), being widowed and divorced (AOR 2.95 (95% CI
(1.50-56.60).
Conclusion and Recommendation: Proportion of Sub therapeutic INR among patients on
warfarin at Jimma Medical center is very high as reflected by low TTR and high level of low
INR. Poor adherence to warfarin, presence of comorbidity and shorter duration of warfarin were
significantly associated with sub therapeutic INR. Therefore, we recommend the physician to
give proper warfarin adherence advice and management of comorbidity.
