Critical reviews in food science and nutrition
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Crit Rev Food Sci Nutr · Jan 2010
Overview of the epidemiology methods and applications: strengths and limitations of observational study designs.
The impact of study design on the results of medical research has long been an area of both substantial debate and a smaller body of empirical research. Examples come from many disciplines within clinical and public health research. Among the early major contributions in the 1970s was work by Mosteller and colleagues (Gilbert et al., 1997), who noted that innovations in surgery and anesthesia showed greater gains than standard therapy when nonrandomized, controlled trials were evaluated compared with the gains reported in randomized, controlled trials. ⋯ In contrast with the prospective analysis in which no relationship between dietary fat and breast cancer was observed, the retrospective analysis yielded a positive relationship for total fat and saturated fat (Giovannucci et al., 1993). By comparing the top quintile versus the bottom quintile of reported intake, the retrospective assessment yielded odds ratios of 1.43 for total fat and 1.38 for saturated fat. Therefore, the magnitude of bias was sufficient to distort evaluation of the diet-disease relationship. (ABSTRACT TRUNCATED)