Copenhagen, Denmark—Having the right type of support system can make a significant difference in coagulation control, according to a new study finding that men prescribed warfarin who live alone have more problems than women in the same situation.

The research
was presented at the European Society of Cardiology (ESC) Congress 2019 meeting in Paris.

“‘Ask my wife”’ is a common reply among older men to questions about their medication, disease, and treatment,” said lead author Anders N. Bonde, MB, of Gentofte University Hospital in Copenhagen.

“Our study suggests that when it comes to anticoagulation control, men are more dependent on their partner than women,” Bonde explained. “Women living alone often have better relationships with children or a broader network of people who could help them manage a demanding medication like warfarin. Furthermore, divorces are often more difficult for men than for women, and the largest percentage of patients with diagnoses related to alcohol abuse (which is known to be important for anticoagulation control) was found in men living alone in our study.”

The issue often is that continuous blood monitoring with international normalized ratio (INR) measurements is required for warfarin to be safe and effective, according to the report. Time in therapeutic range (TTR) is used to measure quality of INR control. ESC guidelines recommend that patients remain in the therapeutic range at least 70% of the time.

While previous studies on anticoagulation control have pinpointed clinical variables that predict low TTR, such as depression or cancer, the study team suggests that few studies have evaluated socioeconomic factors. In this study, researchers focused on the effect of cohabitation status on TTR in men and women with atrial fibrillation (AF).

“Factors that predict low TTR on [vitamin K antagonists] could be used to identify patients who might benefit from interventions, or who would be better treated with a non-VKA oral anticoagulant (NOAC),” the authors write. “Patients living alone may have difficulties in taking their medications, managing their diets, or coming to clinic for monitoring.”

Researchers identified all Danish patients with AF who initiated VKA between 1997 and 2012, singling out those who had 6 months of continuous VKA use and INR monitoring. Patients were grouped based on sex and whether they lived alone or with others.

Overall, 4,772 AF patients with 6 months of continuous VKA use and INR monitoring were identified; 15% of them were men living alone. Another 23% were women living alone, 45% were men not living alone, and 17% were women not living alone.

The study measured INR a median of 11 (interquartile range 8-15) times during the 180 days of VKA use and found that men who lived alone had 0.6 (95% CI, 0.2-1.2) fewer INR measurements during the period.

Furthermore, researchers determined that median TTR was lowest among men living alone (57.2%), followed by women living alone (58.8%), women not living alone (61.0%), and men not living alone (62.5%). 

After multivariable adjustment, men who lived alone had a 3.6% (CI, -5.6 to -1.6) lower TTR compared with men not living alone, yet women who lived alone did not have significantly lower TTR (P = 0.80) compared with women not living alone. The study concluded that living alone had significantly greater effect on TTR among men than among women (interaction P = 0.02) and that men living alone also had higher adjusted INR variability (0.2, CI, 0.0-0.4) compared with men not living alone.

Women living alone also had lower TTR than cohabiting women, but after adjustment the difference was very small (0.2%) and nonsignificant.

“We also found a significant interaction between sex and living alone in our model, meaning that cohabitation status was a strong and important predictor for TTR among men, but not among women,” Bonde said, adding, “Men who live on their own may need extra support to use warfarin, such as education, home visits, telephone contacts, or additional follow-up visits. They might also consider using a newer type of drug, a non-vitamin K antagonist oral anticoagulant (NOAC), which is easier to manage and has fewer interactions with food and drugs compared to warfarin.”

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