Patients may be uninformed about risks of warfarin

Warfarin tablets

ATHENS—A study of patients taking warfarin suggests many do not fully understand the risks associated with the drug.

Researchers asked patients to complete a questionnaire on warfarin use and found that, on average, patients answered 64% of the questions correctly.

The patients tended to be the least informed about food and drug interactions and which side effects necessitate a call or visit to the doctor.

Kjersti Oterhals, RN, PhD, of Haukeland University Hospital in Bergen, Norway, and her colleagues presented these findings at EuroHeartCare 2016 (abstract 36).

“The stroke and bleeding complications from warfarin can be fatal,” Dr Oterhals noted. “Worldwide, warfarin causes the most deaths from drug-related side effects. Patients need to know what foods and drugs have an impact on how warfarin works and what to do if they have symptoms of an overdose or underdose.”

Dr Oterhals and her colleagues evaluated warfarin knowledge in 404 patients with aortic stenosis. The patients’ mean age was 68, and 70% were male.

Nearly two-thirds of the patients (63%) were taking warfarin because they had a mechanical valve, and 24% were taking the drug because they had atrial fibrillation. The remaining patients were taking the drug for unknown reasons (6%) or “other” reasons (7%).

The patients received a postal questionnaire with 28 multiple-choice questions about warfarin. On average, patients answered 18 of the 28 questions correctly. However, 22% of patients answered less than half of the questions correctly.

The questions that were most often answered incorrectly were those concerning food and drug interactions and when to call or see a doctor.

For example, patients were asked which of the following foods would interfere with warfarin: celery, carrots, coleslaw, or green beans. Only 25% correctly said coleslaw. Most patients answered green beans.

“Patients often think green vegetables have the most vitamin K, but that’s not true,” Dr Oterhals said. “Brassica vegetables such as cabbage, broccoli, and cauliflower are rich sources.”

“Patients do not have to avoid these foods, but they should eat an equal amount every week because the vitamin K will decrease their INR and put them at increased risk of thrombosis or embolism. Patients who like to eat a lot of vitamin K-containing foods can take a higher warfarin dosage, but they need to be consistent.”

Dr Oterhals and her colleagues also found that 80% of patients knew they should go directly to the emergency room if they had nose bleeding that would not stop. However, only 45% of patients correctly said diarrhea for more than one day necessitates a visit to the doctor.

The study also showed that increased age was associated with a decrease in correct answers.

“We can only speculate why,” Dr Oterhals said. “Younger people tend to seek out information about how to manage their disease, while the older generation wants the doctor to tell them what to do.”

“Motivated patients should be offered an INR testing kit so that they can monitor their levels and adjust the warfarin dose themselves, just as patients with diabetes who use insulin do. It enables patients to travel and try new foods without having to find a clinic to get tested. Patients tell me that hot weather increases their INR, while another found out while in Asia that nori decreased his INR.”

“Warfarin is a life-saving drug but can be deadly if not used carefully. Health professionals have a responsibility to educate patients, but, unfortunately, even cardiac nurses do not know enough. There is an urgent need to improve health professionals’ warfarin knowledge so they can educate patients.”

Warfarin tablets

ATHENS—A study of patients taking warfarin suggests many do not fully understand the risks associated with the drug.

Researchers asked patients to complete a questionnaire on warfarin use and found that, on average, patients answered 64% of the questions correctly.

The patients tended to be the least informed about food and drug interactions and which side effects necessitate a call or visit to the doctor.

Kjersti Oterhals, RN, PhD, of Haukeland University Hospital in Bergen, Norway, and her colleagues presented these findings at EuroHeartCare 2016 (abstract 36).

“The stroke and bleeding complications from warfarin can be fatal,” Dr Oterhals noted. “Worldwide, warfarin causes the most deaths from drug-related side effects. Patients need to know what foods and drugs have an impact on how warfarin works and what to do if they have symptoms of an overdose or underdose.”

Dr Oterhals and her colleagues evaluated warfarin knowledge in 404 patients with aortic stenosis. The patients’ mean age was 68, and 70% were male.

Nearly two-thirds of the patients (63%) were taking warfarin because they had a mechanical valve, and 24% were taking the drug because they had atrial fibrillation. The remaining patients were taking the drug for unknown reasons (6%) or “other” reasons (7%).

The patients received a postal questionnaire with 28 multiple-choice questions about warfarin. On average, patients answered 18 of the 28 questions correctly. However, 22% of patients answered less than half of the questions correctly.

The questions that were most often answered incorrectly were those concerning food and drug interactions and when to call or see a doctor.

For example, patients were asked which of the following foods would interfere with warfarin: celery, carrots, coleslaw, or green beans. Only 25% correctly said coleslaw. Most patients answered green beans.

“Patients often think green vegetables have the most vitamin K, but that’s not true,” Dr Oterhals said. “Brassica vegetables such as cabbage, broccoli, and cauliflower are rich sources.”

“Patients do not have to avoid these foods, but they should eat an equal amount every week because the vitamin K will decrease their INR and put them at increased risk of thrombosis or embolism. Patients who like to eat a lot of vitamin K-containing foods can take a higher warfarin dosage, but they need to be consistent.”

Dr Oterhals and her colleagues also found that 80% of patients knew they should go directly to the emergency room if they had nose bleeding that would not stop. However, only 45% of patients correctly said diarrhea for more than one day necessitates a visit to the doctor.

The study also showed that increased age was associated with a decrease in correct answers.

“We can only speculate why,” Dr Oterhals said. “Younger people tend to seek out information about how to manage their disease, while the older generation wants the doctor to tell them what to do.”

“Motivated patients should be offered an INR testing kit so that they can monitor their levels and adjust the warfarin dose themselves, just as patients with diabetes who use insulin do. It enables patients to travel and try new foods without having to find a clinic to get tested. Patients tell me that hot weather increases their INR, while another found out while in Asia that nori decreased his INR.”

“Warfarin is a life-saving drug but can be deadly if not used carefully. Health professionals have a responsibility to educate patients, but, unfortunately, even cardiac nurses do not know enough. There is an urgent need to improve health professionals’ warfarin knowledge so they can educate patients.”

Warfarin tablets

ATHENS—A study of patients taking warfarin suggests many do not fully understand the risks associated with the drug.

Researchers asked patients to complete a questionnaire on warfarin use and found that, on average, patients answered 64% of the questions correctly.

The patients tended to be the least informed about food and drug interactions and which side effects necessitate a call or visit to the doctor.

Kjersti Oterhals, RN, PhD, of Haukeland University Hospital in Bergen, Norway, and her colleagues presented these findings at EuroHeartCare 2016 (abstract 36).

“The stroke and bleeding complications from warfarin can be fatal,” Dr Oterhals noted. “Worldwide, warfarin causes the most deaths from drug-related side effects. Patients need to know what foods and drugs have an impact on how warfarin works and what to do if they have symptoms of an overdose or underdose.”

Dr Oterhals and her colleagues evaluated warfarin knowledge in 404 patients with aortic stenosis. The patients’ mean age was 68, and 70% were male.

Nearly two-thirds of the patients (63%) were taking warfarin because they had a mechanical valve, and 24% were taking the drug because they had atrial fibrillation. The remaining patients were taking the drug for unknown reasons (6%) or “other” reasons (7%).

The patients received a postal questionnaire with 28 multiple-choice questions about warfarin. On average, patients answered 18 of the 28 questions correctly. However, 22% of patients answered less than half of the questions correctly.

The questions that were most often answered incorrectly were those concerning food and drug interactions and when to call or see a doctor.

For example, patients were asked which of the following foods would interfere with warfarin: celery, carrots, coleslaw, or green beans. Only 25% correctly said coleslaw. Most patients answered green beans.

“Patients often think green vegetables have the most vitamin K, but that’s not true,” Dr Oterhals said. “Brassica vegetables such as cabbage, broccoli, and cauliflower are rich sources.”

“Patients do not have to avoid these foods, but they should eat an equal amount every week because the vitamin K will decrease their INR and put them at increased risk of thrombosis or embolism. Patients who like to eat a lot of vitamin K-containing foods can take a higher warfarin dosage, but they need to be consistent.”

Dr Oterhals and her colleagues also found that 80% of patients knew they should go directly to the emergency room if they had nose bleeding that would not stop. However, only 45% of patients correctly said diarrhea for more than one day necessitates a visit to the doctor.

The study also showed that increased age was associated with a decrease in correct answers.

“We can only speculate why,” Dr Oterhals said. “Younger people tend to seek out information about how to manage their disease, while the older generation wants the doctor to tell them what to do.”

“Motivated patients should be offered an INR testing kit so that they can monitor their levels and adjust the warfarin dose themselves, just as patients with diabetes who use insulin do. It enables patients to travel and try new foods without having to find a clinic to get tested. Patients tell me that hot weather increases their INR, while another found out while in Asia that nori decreased his INR.”

“Warfarin is a life-saving drug but can be deadly if not used carefully. Health professionals have a responsibility to educate patients, but, unfortunately, even cardiac nurses do not know enough. There is an urgent need to improve health professionals’ warfarin knowledge so they can educate patients.”