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Clinical Scenario


A 66-year-old man of Chinese ethnicity visits you at your clinic for a periodic health examination. He is a retired professor from a local university, regularly wins games at the local chess club, and is physically active. However, his medical history reveals that he experienced a mild stroke 2 years ago. He still feels some heaviness in his left arm and lower extremities, but his speech has returned to normal and he is independent in his daily activities. He is even able to jog 2 km daily at a slow pace. He has never smoked. He drinks 2 to 3 glasses of wine every day. Further inquiry reveals that he has primary hypertension and type 2 diabetes mellitus and that he was diagnosed as having atrial fibrillation (AF) a year before his stroke.

The physical examination findings are unremarkable except for a blood pressure of 130/90 mm Hg and an irregular heart rate of 64/min. An electrocardiogram confirms that he indeed has AF.

The patient is taking 500 mg of metformin twice a day for his diabetes and 10 mg of ramipril once a day for his hypertension. Both the diabetes and hypertension have been well controlled for the past year. His only drug for stroke prevention is aspirin, 325 mg once a day.

Because the patient has a high risk for a recurrent embolic stroke, you consider prescribing an oral anticoagulant. You have used mostly warfarin in your practice, but in the past year, you have been discussing dabigatran etexilate, a novel anticoagulant recently approved by the US Food and Drug Administration for stroke prevention in AF, with some of your patients. Recently, you have heard concerns about the safety of warfarin among Asians, so you wonder if dabigatran would be a better choice for this patient.

Finding the Evidence

You send the patient for some blood tests and promise to discuss therapeutic options for stroke prevention when he returns. That evening, you decide to get an overview of current best evidence of using dabigatran etexilate in Asian patients with AF. Using the federated search engine ACCESSSS (, you enter the 2 search terms “dabigatran” and “Asia,” which retrieves available evidence from all levels of the pyramid of evidence-based medicine resources (see Chapter 5, Finding Current Best Evidence). Starting with the summaries at the top, you find general chapters in Best Practice and UpToDate but are not satisfied with the applicability of the evidence to Asian patients. On the level of preappraised research, you notice that no sound systematic reviews of studies are found in any resource searched (eg, ACP Journal Club, DARE, Cochrane, or MacPLUS). You then look at the bottom of the pyramid, where nonpreappraised research from PubMed is shown. Under the section filtered for reviews, you find a guideline entitled “Asian Venous Thromboembolism Guidelines: Prevention of Venous Thromboembolism,” published in International Angiology...

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