Drug Res (Stuttg) 2020; 70(12): 570-575
DOI: 10.1055/a-1228-5033
Original Article

Evaluation of Stable Doses of Warfarin in a Patient Cohort

1   Department of Pharmacology & Therapeutics, College of Medicine and Medical Sciences, Arabian Gulf University, Manama, Kingdom of Bahrain
Rashed Al Banny
2   Department of Cardiology, Salmaniya Medical Complex, Ministry of Health, Manama, Kingdom of Bahrain
Aysha Husain
2   Department of Cardiology, Salmaniya Medical Complex, Ministry of Health, Manama, Kingdom of Bahrain
3   RCSI-Bahrain, Manama, Kingdom of Bahrain
› Author Affiliations
Funding: This study was part of the research project supported by AGU RCSI 2019-2 grant.


Background Definitions for stable dose of warfarin varies in the reported studies. International warfarin pharmacogenetic consortium (IWPC) algorithm was generated from the data based on these definitions.

Objective In the present study, we primarily evaluated whether any significant differences exist between the definitions for stable warfarin dose.

Methods A prospective cross-sectional study in adults receiving warfarin for at least 3 months was carried out. Stable doses of warfarin as defined in previous studies were compared with the standard definition. Bland-Altman plots, Pearson’s correlation and intra-class coefficients (ICC) were used to assess the correlation, reliability and agreements between the doses.

Results Sixty-four patients were recruited. Twenty definitions were obtained from the previous studies. We observed that all but one showed very high or high positive correlations; and either excellent or good ICC. No significant differences between the doses initiated and predicted by IWPC algorithm.

Conclusion We observed similar stable doses between the definitions except for one. Hence, IWPC algorithm may not have any bias associated with inclusion of any studies with variable definitions for stable warfarin dose.

Supporting Information

Publication History

Received: 15 June 2020

Accepted: 25 July 2020

Article published online:
20 August 2020

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