Patient education and oral anticoagulant therapy

Abstract

Background and objectives: The stability of oral anticoagulant therapy is affected by an irregular intake of vegetables, interactions with other drugs, intercurrent disease, and compliance. With the aim of investigating whether educating patients could affect anticoagulation stability, we prepared a questionnaire on the basis of some fundamental information given by us to our patients during their first attendance to our clinic. Moreover we sought to determine whether administering the questionnaire would be useful in improving the anticoagulation stability of patients whose anticoagulation was poorly controlled.

Design and methods: The questionnaire was administered to a group of 219 anticoagulated patients attending our Thrombosis Center. All patients were invited to fill in the questionnaire, which was handed out by a nurse, while they were waiting for their blood sampling results. None of the patients refused to fill in the questionnaire, which was completed at once and independently. The answers to the questionnaire were correlated with the time spent by the patients in the therapeutic range.

Results: A significant difference was found between the time spent in the therapeutic range by patients who declared a regular intake of their therapy (91%, 14-100%) and that spent in the range by those who answered they sometimes forgot to take it (75%, 9-100%). The percentage of time spent in the therapeutic range was significantly longer (92%, 36%-100%) in patients who reported regular vegetable intake and in those that never ate vegetables than that observed in patients who admitted occasional intake of vegetables (86%, 5%-100%). In the group of patients below 65 years of age, a significant difference in the time spent in the therapeutic range was observed in the case of regular assumption of oral anticoagulant drugs (95% vs 68%, p<0.01) and in that of regular daily vegetable intake (95% vs 86%, p=0.03). The difference in time spent in the range between patients who knew why they were taking the oral anticoagulant and those who did not was statistically significant only in the older group (89% vs 76%, p=0.04). In women, the time spent in the therapeutic range depended on regular vegetable intake (92% vs 74%, p=0.02), assumption of other drugs (91% vs 72%, p=0.02), and intercurrent disease (92% vs 76%, p=0.04). In men a significant difference was observed in favor of those who knew why they were taking oral anticoagulants (93% vs 83%, p<0.01). Logistic regression analysis showed that the risk of being below the chosen cut-off of the time in range (90%) was 6.0 (C.I. 95%: 2.2-16.3) in those patients who sometimes forgot their daily dose even though they knew why they were taking the oral anticoagulant. Moreover, the risk of being below the cut-off was 3.0 (C.I. 95%: 1.3-6.5) in those who never forgot to take their therapy, but did not know the reason why they were taking oral anticoagulants. Finally we observed a significant improvement in the time spent in the range by patients with poor anticoagulation control when we included the three months before and after the questionnaire in our analysis.

Interpretation and conclusions: In conclusion we believe: 1) that greater emphasis should be given to educational courses for anticoagulated patients especially in consideration of age and gender differences; and 2) on its own, administration of the questionnaire leads to a significant improvement in the time spent by patients in the therapeutic range.