Category: Professional Posters
Purpose: Qatar has some of the highest rates of metabolic disorders (including obesity) within the region. A recent report indicated that more than 70 percent of Qatar’s population is either overweight or obese. Evidence supporting the effect of body mass index (BMI) on warfarin maintenance doses and anticoagulation control is contradicting.
The purpose of this study was to investigate whether a correlation exists between BMI and weekly warfarin dose required to maintain a stable therapeutic INR and whether an individual's BMI could affect anticoagulation control reflected by mean time in therapeutic range (TTR) and the incidence of thromboembolic and/or bleeding events.
Methods: A retrospective cross sectional study of adult patients (>18 years old) receiving stable doses of warfarin, defined as having a therapeutic INR without a change in warfarin dose for at least 6 weeks, and attending ambulatory anticoagulation clinic in Hamad General Hospital, a tertiary teaching hospital in Qatar, over one year period (July 1st 2016 - June 30th 2017).
Patients with missing data (demographics, target INR), those known to have poor compliance to warfarin and/or clinic visits or those who lost follow up with the clinic were excluded.
Relevant data were collected through electronic chart review. These include, patients’ demographics, indication and duration of warfarin therapy, target INR, comorbidities (e.g., diabetes, hypertension, renal and hepatic dysfunction), tobacco use, the presence of drugs known to significantly interact with warfarin as well as any reported incidents of bleeding (along with type/severity of the bleeding) and thrombosis were collected.
TTR was calculated using Rosendaal method.
BMI, the independent variable, was analyzed as a continuous and categorical variable (six BMI categories: underweight, normal weight, overweight, obese, morbidly, and severely obese) and was then correlated with warfarin dose ( weekly and mg/kg) accordingly.
Results: A total of 159 patients were included (57.9% males). The BMI ranged between 14.3 – 61.8 kg/m2 (median 30.56 kg/m2) and the mean TTR (± standard deviation) was 78 (± 18.2)
Overall, there was a weak positive correlation between BMI and weekly warfarin maintenance dose (Pearson's r 0.186, P=0.019).
When comparing mean TTR across different BMI categories, no differences were observed (P-value =0.61).
There was, however, a weak negative correlation between BMI and weekly mg/kg warfarin dose (Pearson's r -0.22). When compared to normal BMI, morbid and severely obese patients had lower weekly mg/kg warfarin doses requirements (P-value of 0.037 and 0.028 respectively).
Among 159 patients, no thrombotic events were detected. Thirteen incidents of minor bleeding were reported with insignificant differences detected across different BMI categories (P=0.62).
Conclusion: A weak positive correlation exists between BMI and total weekly warfarin dose. No correlation was observed between BMI and anticoagulation control.