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.