Therapeutic Anticoagulation Prevalence among Patients of a Cardiology Clinic receiving Warfarin and Association with Overweight

Vitamin K epoxide reductase which is essential for the formation of reduced vitamin K, a co-factor for the hepatic synthesis of the clotting factors II, VII, IX and X [2].The outcome of warfarin therapy varies among individuals due to factors such as genetics, age, ethnicity, diet and weight which have been shown to have varying impact on therapeutic anticoagulation [3][4][5][6][7][8][9][10].Although many studies have reported benefits of the use of these parameters to determine warfarin doses, clinically guided management still relies heavily on monitoring International Normalized Ratio (INR).The primary objective of the study was to examine the prevalence of therapeutic anticoagulation with warfarin among patients registered in a setting where clinically guided management is the only available system for monitoring warfarin efficacy.The secondary objectives of the study include an assessment of the differences between subjects that are within the target INR range (therapeutic anticoagulation) and those subjects outside the target INR (non-therapeutic anticoagulation). MethodsThis was a cross-sectional, observational, convenience sample study of adults (at least 18 years of age) on warfarin maintenance therapy recruited from the University Hospital of the West Indies Cardiology Clinic in the two time periods (January 2014-May 2014 and February 2015 -October 2015).Inclusion criteria also required subjects to be warfarin for more than one month and self-report of good compliance.Informed consent guidelines were followed and all subjects recruited in this study consented to participate.After Informed Consent was obtained, information recorded included daily dose, date of initiation, and indication for warfarin therapy.Also recorded for each subjects was age, weight, height, gender, ethnicity and concomitantly administered drugs. INR assessmentA single sample of one drop (≥ 8µL) of capillary blood from each patient, obtained by pinprick was used to obtain INR Abstract Introduction: Warfarin is the main anticoagulant therapy offered in Jamaica; however, no published data is available evaluating prevalence of therapeutic anticoagulation among this population. Methods:A cross-sectional study conducted at the Cardiology Clinic of the University Hospital of the West Indies from January 2014-May 2014 and February 2015-October 2015 of patients on warfarin therapy for more than one month and a self-report of good compliance.International Normalized Ratio (INR) was obtained by one drop of capillary blood applied to CoaguChek XS Plus monitor; age, ethnicity, gender, warfarin dose were recorded and body mass index (BMI) was calculated.Results: Of the 65 subjects, most were of Afro-Caribbean ethnicity (n=60), predominantly females (44; χ2= 8.1, p=0.004), median age was 59 (range 26-91) years and the median BMI was 26.7(range 18.8-45.0kg/m 2 ).Daily warfarin doses range from 2.5 mg to 10.0 mg.Therapeutic anticoagulation (INR of 2.0-3.0 or 2.0-3.5, dependent on condition) was observed in 17 (26.2%)subjects; significantly more of the subjects, 48 (73.8%), presented with nontherapeutic INR (χ2=14.8;p<0.001).BMI was positively correlated with therapeutic INR (Spearman's rho = 0.28; p=0.027).Subjects within the therapeutic INR had significantly higher median BMI, 30.2 (interquartile range=11.8kg/m 2 ) than subjects with non-therapeutic INR, 26.0 (interquartile range= 7.4 kg/m 2 ) (Mann-Whitney test, p=0.028), however there was no difference in the warfarin dose between groups.Conclusions: There is a high prevalence of non-therapeutic anticoagulation among subjects in this study.Subjects with therapeutic anticoagulation were significantly overweight, suggesting a need to further examine the relationship between overweight and vitamin K status in this population.