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Figure 4. Risk difference in all-cause mortality for randomized, controlled trials of vitamin E supplementation and pooled results for low-dosage (<400 IU/d) and high-dosage ( 400 IU/d) vitamin E trials on the basis of 4-way analyses of trials that used a factorial design. The area of each square is proportional to the inverse of the study variance in the analysis. Horizontal lines represent 95% CIs. We restricted data from factorial trials to participants who were not exposed to the second factorial intervention, except for the Heart Outcomes Prevention Evaluation (HOPE) study (44) and the Medical Research Council/British Heart Foundation Heart Protection Study (MRC/BHF HPS) (49) (in which no disaggregated data were available) and for the Linxian A (36) trial (which used a fractional factorial design). For these trials and the trials that did not use a factorial design, we kept the results from 2-way analyses. ADCS = Alzheimer's Disease Cooperative Study; AREDS = Age-Related Eye Diseases Study; ATBC = Alpha-Tocopherol, Beta Carotene Cancer Prevention Study Group; CHAOS = Cambridge Heart Antioxidant Study; DATATOP = Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism; GISSI-Prevenzione = Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarcto Miocardio Prevenzione; MIN.VIT.AOX = The Geriatrie/MINéraux, VITamines, et AntiOXydants Network; PPP = Primary Prevention Project; PPS = Polyp Prevention Study; REACT = Roche European American Cataract Trial; SPACE = Secondary Prevention with Antioxidants of Cardiovascular disease in Endstage renal disease; SU.VI.MAX = SUpplementation en VItamines et Minéraux AntioXydants; VECAT = Vitamin E, Cataracts, and Age-Related Maculopathy; WAVE = Women's Angiographic Vitamin and Estrogen.
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