Quality of Oral Anticoagulation Control with Warfarin According to Sex: A Cross-Sectional Study

Evidence indicates a difference between men and women in oral anticoagulation control, but the results were discrepant. This study investigated the association of sex with oral anticoagulation control in patients on warfarin assisted by anticoagulation clinics (ACs) in Brazil. The cross-sectional study included patients on warfarin recruited at three public ACs in southeast Brazil (2014–2015). The quality of oral anticoagulation was estimated by the time in therapeutic range (TTR). Univariable and multivariable linear regression models were built to examine the association of sociodemographic, behavior, clinical, and drug therapy variables with TTR. Overall, 801 participants were studied (455; 56.8% women), with a mean age of 65.0 (13.4) years. The female sex was associated with lower TTR than the male sex (Beta (95% CI) = −17.01 (−30.25; −3.76), p = 0.012), however, this difference decreased with increasing age, becoming null after age 60. Smoking patients had a lower TTR than non-smokers (−5.18 (−10.02; −0.34), p = 0.036). The results showed that the association of sex with oral anticoagulation control is dependent on age. Women have lower TTR than men, but this difference is null in older patients. Knowledge of these factors may be useful for developing strategies to improve care for these patients.