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Advances in medical toxicology are achieved through the scientific method using observations, derived from cases of poisoning and nonpoisoning due to xenobiotic exposures, to generate hypotheses. Subsequent research questions are analyzed with epidemiological investigation, and preliminary studies are examined with methodological scrutiny. Initial analytical techniques are improved, and confirmatory studies are performed. Ultimately, models relating cause to effect are formulated.

To optimize patient care, it is useful to grade the quality of available scientific evidence used to justify treatment recommendations. Decisions about how strongly to recommend a medical action will be based on the careful consideration of the risks of leaving a patient untreated, the potential benefits and harms of treatment, the quality of the guiding evidence, a balanced view of resource utilization, and the values of the person to be treated. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group has provided a framework for assessing and communicating levels of scientific evidence (Table 138–1).22 An understanding of basic principles of research design and epidemiology is required to interpret published studies and to lay the groundwork for future investigation in toxicology.

TABLE 138–1.GRADE System for Evaluating Clinical Recommendations


Table 138–2 lists the different study formats discussed below.

TABLE 138–2.Epidemiologic Study Designs: Types, Measurements, and Advantages

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