| Summary: | 碩士 === 國立臺灣大學 === 臨床藥學研究所 === 93 === Patients with atrial fibrillation (AF, ICD-9 427.31) have a 5 to 17 fold increased risk of stroke when compared with patients without AF. Stroke prevention has become the standard of care. Six large randomized trials of stroke prevention in AF published from 1989 to 1993 had consistenly shown the benefit of warfarin therapy, with a risk reduction of 62%. Despite consensus that warfarin is strongly indicated in most patients with atrial fibrillation, past studies demonstrate that anticoagulation in AF patients is inadequately used.
This study included patients visited National Taiwan University Hospital (NTUH) with a diagnosis of AF, from 2000 Jan 1 to 2004 July 30. We used ACC/AHA/ESC guideline released in 2001 to stratify our patients into 4 levels. We analyzed (1) demographic characteristics, (2) prescribing patterns of antithrombotic agents, (3) warfarin prescribing adherence with practice guidelines, (4) the association between warfarin usage and ischemic stroke or TIA complications, (5) the association between warfarin usage and cerebral or GI bleeding complications, (6) INR levels of stable patients under warfarin treatment, and (7) evaluation of the predictor factors of warfarin prescription.
In our study, we included 5,448 patients, the average age (± SD) was 67 ±14 years (range, 0-92 years). The prevalence was higher in men (1.25 : 1). The most frequent comorbidities in patients with AF were hypertension (54.6%), coronary artery disease (40%), heart failure (26.6%), and diabetes mellitus (21.6%). Based on ACC/AHA/ESC guideline, our patient distribution from lowest risk to highest risk were 9%, 10%, 69%, and 13% respectively.
Among 761 patients with warfarin treatment for atrial fibrillation, 32 hospital admissions with the diagnosis of ischemic stroke (ICD-9 434) or TIA (ICD-9 435). After adjusted age and sex, the odds ratio was 0.33 (95% CI, 0.22-0.47). Since we use person and not episode in our analysis, we might underestimate the incidence of ischemic stroke or TIA. In prescribing behavior, 169 patients were prescribed with warfarin after ischemic stroke or TIA.
Among 991 patients with warfarin treatment for atrial fibrillation, 35 hospital admissions with the diagnosis of cerebral hemorrhage (ICD-9 431) or GI bleeding (ICD-9 578), after adjusted age and sex, the odds ratio was 0.51 (95% CI, 0.36-0.73). When we analyzed GI bleeding alone, the adjusted odds ratio was 0.52 (95% CI, 0.36-0.88). Our findings are unsual in that warfarin usage is decrease the risk of GI bleeding. Several reasons may, in part, explain this finding. There were some confounding factors of GI bleeding, we didn’t exclude patients with peptic ulcers or stress ulcers. Compared with ulcers, warfarin-induced GI bleeding was relatively low. In the other way, we analyse cerebral hemorrhage alone, the adjusted odds ratio was 1.77 (95% CI, 0.43-7.30). Warfarin usage was lack association with cerebral hemorrhage. The incidence of cerebral hemorrhage or GI bleeding increased with age, and most patients had INR level of 3.5 (34%). The INR levels of stable patients under warfarin treatment was 1.6
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