epidemiology - required reading

epidemiology - required reading - Gordis Epidemiology (4th...

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Gordis – Epidemiology (4 th Edition) pp 131-134 : Randomized Controlled Trials Chapter 7 – Assessing the Efficacy of Preventive and Therapeutic Measures: Randomized Trials All who drink of this treatment recover in a short time, Except those whom it does not help, who all die, It is obvious, therefore, that it fails only in incurable cases. —Galen [1] (129–c. 199 ce) Some ways of quantifying the natural history of disease and of expressing disease prognosis were discussed in Chapter 6 . Our objective, both in public health and in clinical practice, is to modify the natural history of a disease so as to prevent or delay death or disability and to improve the health of the patient or the population. The challenge is to select the best available preventive or therapeutic measures to achieve this goal. To do so, we need to carry out studies that determine the value of these measures. The randomized trial is considered the ideal design for evaluating both the effectiveness and the side effects of new forms of intervention. The notion of using a rigorous methodology to assess the efficacy of new drugs, or of any new modalities of care, is not recent. In 1883, Sir Francis Galton, the British anthropologist, explorer, and eugenicist, who had a strong interest in human intelligence, wrote as follows: It was asserted by some that men possess the faculty of obtaining results over which they have little or no direct personal control, by means of devout and earnest prayer, while others doubt the truth of this assertion. The question regards a matter of fact, that has to be determined by observation and not by authority; and it is one that appears to be a very suitable topic for statistical inquiry. … Are prayers answered or are they not? … Do sick persons, who pray or are prayed for, recover on the average more rapidly than others? [2] As with many pioneering ideas in science and medicine, many years were to pass before this suggestion was actually implemented. In 1965, Joyce and Welldon reported the results of a double- blind clinical trial of the efficacy of prayer. [3] The findings of this study did not indicate that patients who were prayed for derived any benefits from that prayer. A more recent study by Byrd, [4] however, evaluated the effectiveness of intercessory prayer in a coronary care unit population using a randomized double-blind protocol. The findings from this study suggested that prayer had a beneficial therapeutic effect. In this chapter and the one following, we discuss possible study designs that can be used for evaluating new approaches to treatment and prevention, and focus on the randomized trial. Although the term randomized clinical trial is often used together with its acronym, RCT, the randomized trial design also has major applicability to studies outside the clinical setting, such as community-based trials. For this reason, we use the term randomized trial. To facilitate our discussion, reference is generally made to treatments and drugs; the reader should bear in mind that the principles described apply equally to
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epidemiology - required reading - Gordis Epidemiology (4th...

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