Article; Study country; Year of Publication [Reference no] | Type of study | Sample size | Main Findings | Conclusion |
Abohelaika et al.; UK; 2016 [21] | Longitudinal study | 2094 | - Warfarin dose changes and INR monitoring frequency decrease until the age of 67 and increases as they get older - TTR according to age was significantly lower - Females have a higher probability of TTR ≤ 65% compared to male - Patients under domiciliary service have a higher probability of TTR ≤ 65% compared to those in general practice and hospital-based clinics | Anticoagulation control is influenced by age, gender and physical dependence |
Al-Momany et al.; Jordan; 2019 [58] | Cohort study | 2788 | - Factors such as concurrent medication use (46.9%), smoking cigarettes and shisha (17%), non-balanced vitamin K dietary intake (16.88%) lower the INR value - Herbal supplements (Hawthorn and Ginseng) are associated with supratherapeutic INR value. | Smoking shisha and cigarettes, concurrent medication use, herbal use and increased vitamin K consumption are associated with non-therapeutic INR value. |
Bernaitis et al.; Australia, Singapore; 2017 [20] | Retrospective cohort study | 4366 | - Mean TTR is significantly higher in Australia than Singapore - Anemia and age < 60 years influence the INR control in Australia - The INR control in Singapore is influenced by factors such as vascular disease, concurrent platelet inhibitor therapy and CHA₂DS₂-VASc score of 6 | Multiple patient factors influence the INR control in both these countries |
Bjorck et al.; Sweden; 2019 [62] | Retrospective cohort study | 28,011 | - The prevalence of excessive alcohol consumption is higher in patients with iTTR < 60% - Concomitant comorbidities are associated with poor INR control - Patients with previous stroke have iTTR > 70% | Excessive alcohol consumption is the most significant predictor of poor INR control. Concomitant disorders are associated with poor INR control. |
Bourgeois et al.; UK; 2016 [59] | Prospective cohort study | 711 | - CYP2C9 and VKORC1 are the major genetic determinants of warfarin dosing - Age, height, weight, alcohol consumption and concomitant drugs influence the warfarin dosing and initial response to warfarin. | Genetic and other multiple factors such as age, height, weight, concomitant drugs use, and alcohol consumption are important determinants of warfarin dosing. |
Chalachew et al.; Ethiopia; 2019 [53] | Cross-sectional study | 73 | - Educational level of less or equal to primary school, decrease in check-up visit frequency, distance of more than 300km from the follow-up medical facility and public health institution as a source of free warfarin supply are associated with subtherapeutic INR control. | Distance from follow-up facility, educational level, follow-up visits number and source of warfarin supply are significantly associated with subtherapeutic INR control. |
Cohen et al.; USA; 2019 [17] | Retrospective cohort study | 4556 | - Peripheral vascular disease, chronic obstructive pulmonary disease (COPD), non-black race, mild liver disease, no statin use and low weight are associated with supratherapeutic INR value. - The prevalence of INR overshoot in older adults on newly initiated warfarin therapy during acute hospitalization is 8%. - Patients with INR overshoot experienced a significantly higher rate of mortality, bleeding events and length of stay in hospital. | Peripheral vascular disease, chronic obstructive pulmonary disease (COPD), non-black race, mild liver disease, no statin use and low weight are sensitivity markers of INR overshoot. |