Clinical characteristics and overdose risk factors of patients hospitalized due to warfarin overdose

Abstract

Objectives: This study aims to investigate the relationship between overdose and patient characteristics by specifying characteristics such as age, gender, comorbidity, laboratory, diet, and treatment in patients hospitalized due to warfarin overdose. Materials and methods: A total of 167 (91 males, 76 females, mean age 77±12 years; range 26 to 94 years) consecutive patients hospitalized at the Göztepe Training and Research Hospital Internal Medicine Clinic between May 2015 and May 2016 with International Normalized Ratio (INR) >3.50 were included in the study. Demographic data, comorbidity states, warfarin indications, thromboembolic risk scoring (CHA2DS2-VASc), bleeding risk score (HASBLED), laboratory parameters and previous hospitalizations for the same cause, current medications, diet, and bleeding origin of patients were documented. Results: The most common warfarin indication was atrial fibrillation and the most common comorbidity was hypertension. Mean warfarin dosage was 30.8±8.7 mg/week. Mean CHADS2-VASC was 4.2±1.2, mean HASBLED was 3.6±0.9, mean INR was 8.0±3.6, and mean Time in Therapeutic Range (TTR) was 28.7±22.6%. The most common drug with warfarin interaction were proton pump inhibitor. A total of 68.9% of patients were found to be using over five medications and %21.6 of patients consuming food with possible warfarin interaction. Rate of rehospitalization due to warfarin overdose was %28.7. Bleeding frequency was %58.1. Mean INR and HASBLED was higher and mean TTR (p=0.04) was lower in patients with bleeding compared to non-bleeding patients (p=0.007, p<0.001). Male gender (p=0.007) and high HASBLED score (p<0.001) were independent risk factors for bleeding. Conclusion: In inpatients hospitalized due to warfarin overdose, medications, and consumption of foods interacting with warfarin were found to be frequent; almost one third of patient were rehospitalized due to warfarin overdose, and high HASBLED score, and low TTR was associated with higher bleeding risk.