Randomized trials of warfarin for atrial fibrillation.
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Biomedical subjects
Publications and source records attributed to D E Singer.
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PURPOSE: To determine the appropriate patients, methods, and timing for screening for diabetic retinopathy. DATA SOURCES: Relevant articles were identified through prominent review articles, the authors' files, recommendations from experts, and a MEDLINE search (1986 to the present); additional references were selected from the bibliographies of identified articles. STUDY SELECTION: Selection of articles on the natural history of retinopathy was limited to large clinical series and formal epidemiologic studies of defined populations. Selection of articles on the therapeutic effect of photocoagulation and of glycemic control was limited to randomized trials. Sources bearing on the accuracy of screening modalities were necessarily more varied. DATA EXTRACTION: For important variables, individual estimates from multiple studies are presented rather than a single meta-analytic summary estimate. RESULTS: Screening for retinopathy is justifiable if early detection leads to less vision loss at an acceptable cost. The evidence shows that 1) laser therapy reduces the rate of vision loss by 50% among patients with proliferative retinopathy and macular edema, conditions that are often asymptomatic; 2) duration of diabetes is the main risk factor for retinopathy; and 3) standard ophthalmoscopic examination has only moderate sensitivity (about 80% in research settings) and specificity (greater than 90% for proliferative retinopathy but lower for macular edema), making seven-field stereophotography a more accurate method. Estimates of cost effectiveness indicate that screening for retinopathy not only saves years of vision but may be cost saving from a societal perspective. CONCLUSIONS: Screening for retinopathy in patients with diabetes, and subsequent photocoagulation therapy for those who have high risk macular edema or proliferative retinopathy, is clearly beneficial.
Recent randomized trials have consistently demonstrated the marked efficacy of warfarin in reducing the risk of stroke caused by nonrheumatic atrial fibrillation. These trials have provided conflicting evidence on the effect of aspirin. We report the aspirin analysis from the BAATAF study, a trial in which control patients could choose to take aspirin. There we two strokes in 446 person-years with warfarin (annual rate of 0.45%); eight strokes in 206 person-years with aspirin, most at 325 mg per day (annual rate of 3.9%); and five strokes in 271 person-years among patients taking neither aspirin nor warfarin (annual rate of 1.8%). Simultaneously controlling for the other significant determinants of stroke in the BAATAF study (age, mitral annular calcification, and clinical heart disease), the relative rates (95% confidence interval) of stroke were: (1) warfarin/aspirin = 0.135 (0.029 to 0.64); (2) aspirin/(no aspirin and no warfarin) = 1.95 (0.64 to 5.97); and (3) warfarin/(no aspirin and no warfarin) = 0.263 (0.051 to 1.36). Our "treatment received" analysis argues that warfarin is strikingly more effective than aspirin in preventing stroke in nonrheumatic atrial fibrillation.
We studied the cross-sectional relationship between HbA1c and cardiovascular disease (CVD) in the survivors of the original cohort of the Framingham Heart Study (n = 1045). HbA1c was significantly related to prevalent CVD among women but not men. HbA1c was also related to hypertension and to the ratio of total to high-density lipoprotein cholesterol levels. In regression analyses that controlled for these and other potential risk factors, HbA1c remained significantly related to CVD among women. The relative odds of CVD increased 1.39-fold (95% confidence interval 1.06-1.83) for increases in HbA1c of 1% (e.g., for HbA1c from 5 to 6%). The relationship was not weakened when known diabetic subjects or subjects taking beta-blocker or thiazide medications were excluded from analysis. In contrast, there was no significant relationship between "casual" blood glucose and prevalent CVD. Our results reveal a strong, significant, independent association between hyperglycemia, measured by HbA1c, and CVD among older women.
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