Garcia-Sempere et al.; Spain; 2019 [38]	Cross-sectional study	22,629	- 53% of women and 49.3% of men had poor INR control with TTR ≤ 65%. - Women, long-term antiplatelet users, use of alcohol and concomitant comorbidities are associated with poor INR control.	Women are with a higher risk of poor INR control.
Jaakkola et al.; Finland; 2017 [3]	Clinical trial	13,618	- Chronic medical conditions such as heart failure, chronic kidney disease, mechanical heart valve prosthesis and active cancer are permanent risk factors of excessive warfarin anticoagulation. - Chemotherapeutic agents, antibiotic and antifungal treatment are temporary risk factors of excessive warfarin anticoagulation - Active smoking and alcohol abuse are risk factors of excessive warfarin anticoagulation.	Identifying these risk factors is helpful in the early detection and prevention of supratherapeutic INR.
Katada et al.; Japan; 2019 [68]	Retrospective observational study	58	- The maximum INR of prothrombin time (PT-INR) and warfarin sensitivity index (WSI) are significantly higher in patients who are fasting during the postoperative period compared to those with no dietary intake reduction.	Postoperative fasting is significantly associated with INR control.
Liang et al.; China; 2019 [24]	Prospective registry study	1895	- Age ≥ 70 years, use of a single drug, bleeding history and lack of assessment of bleeding risk is associated with TTR < 70%. - Peripheral arterial disease, coronary artery disease and diabetes mellitus are associated with increased variability of INR.	Warfarin anticoagulation in Chinese patients with NVAF is associated with lower TTR than in current guidelines and affected by multiple risk factors.
Martin-Perez et al.; Spain; 2019 [35]	Nested case-control study	12,506	- Multiple factors, including low socioeconomic status and residency in rural areas are associated with poor INR control.	Low socioeconomic status and residency in rural areas are associated with poor INR control.
Numao et al.; Japan; 2017 [22]	Cohort study	626	- Older age ≥ 75 years is an independent predictor of high INR variability	Identifying the factors related to high INR variability in AF patients may assist the clinician in identifying patients likely to show unstable INR control.
Ohara et al.; Japan; 2019 [50]	Prospective cohort study	309	- African American patients have 30% lower S-warfarin clearance [CL(S)] compared to Asian and White patients - Half maximal effective concentration (EC50) showed a greater racial difference than CL(S). - Age, weight, sex and African American ethnicity are significant predictors of INR	African American has higher warfarin requirement than Asian and White patients
Praxedes et al.; Brazil; 2019 [54]	Retrospective cohort study	312	- Assistance for warfarin administration, female gender, absenteeism and non-compliance are associated with TTR ≤ 60%	Patient’s behaviour towards treatment influence the TTR.
Prochaska et al.; Germany; 2019 [29]	Cohort study	760	- Female sex and living alone are independent risk factors of INR control - Self-management of warfarin therapy is a protective factor.	Women and living alone patients have a higher risk of low-quality warfarin therapy.
Schaefer et al.; Switzerland; 2016 [80]	Cohort study	15,834	- High intensity of therapeutic range, female sex, intervals of more than 14 days between measurements and management other than PSM are predictors of poor INR control.	Several factors influence poor INR control in PSM cohort.