Factors affecting warfarin control in patients attending the warfarin clinic in the cardiac surgical center in Ahmed Ghasim hospital (2010)

Abstract

Background Warfarin is a commonly used medication with a narrow therapeutic index. The initiation of warfarin requires consideration of a variety of factors, which include reviewing the indications and contraindications for this agent, performing a thorough clinical assessment along with a riskbenefit analysis for anticoagulation, consideration of warfarin pharmacology, developing strategies to monitor the intensity of anticoagulation and for the detection of adverse events, and education of the patient. Design: Descriptive prospective cross sectional study. Setting: This study held at the cardiac surgery and renal transplant center in Ahmed Ghasim Hospital. Objectives: The different factors which affect proper warfarin control the level of knowledge,and the degree of control in one hundred patient were assessed Methodology: Patient knowledge about the warfarin dose, the time of administration, the effect of diet, drug interaction with warfarin and the incidence of complication were studied using a direct questionnaire and the last INR was measured to identify the level of control. Results: The results were compared to the results of a similar Sudanese study which was conducted at 2000 in the same hospital in the same number IV of patients. In our study 38% of the patients were properly controlled having an INR within the therapeutic range, in contrast to the previous study when the number is 34%, 20% of our patients had good level of education regarding warfarin, compared to 16% in the previous study .60% of our patients did not received any education programme about warfarin, 71.4% of them were educated after starting the therapy. 60% of the patients were taking different medication with different interaction with warfarin.88% of the patients knew the different interaction of warfarin with different types of diet.70% of the population studied live far from the center outside Khartoum state. Only 2 of our patients were provided with the warfarin booklets, and they obtained it from another hospital, in the previous study 12 of the patients had the booklet and they obtained it from abroad. 36% of our patients suffered from bleeding, the commonest site was epistaxis, 36.2% from them had bleeding for several times, compared to12% in the previous study this reflects the bad control as 33% of our patients had prolonged INR, compared to one patient in the previous study. Only 2 of our patients suffered from one attack of cerebral thrombosis in the form of cerebrovascular accident. School education did not seem to affect warfarin control since in both educated and illiterate patients, the percentage of those who had controlled INR are similar. The optimum maintainace dose was found to be 3-5mg. Conclusion: From this study it was concluded after 10 years that more than half of the patients were not well controlled having an INR outside the therapeutic range, the most significant causes of poor control were lack of full education about the drug and the far residence from hospital and laboratories and the high cost of the INR investigation. Bleeding endangered a large number of our patients life. Thrombosis still seemed to be a rare complication.