International journal of technology assessment in health care
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Int J Technol Assess Health Care · Jan 1989
Review Comparative StudyPragmatic versus explanatory trials.
This article considers the distinction between "explanatory" and "pragmatic" aims in clinical trials--the distinction between testing a biological hypothesis and providing evidence to permit a choice between alternative treatment policies. The choice of treatments to compare, the selection of patients for the trial, the study size, and how the treatment comparison should be made are among the matters discussed. In general, where explanatory and pragmatic aims conflict, the pragmatic aim will often take priority.
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Int J Technol Assess Health Care · Jan 1989
Review Randomized Controlled Trial Clinical TrialNonexperimental data systems in surgery.
This article reviews nonexperimental data bases, emphasizing the present uses and future opportunities of routinely collected information. Data bases are discussed in terms of appropriate research designs. Possibilities for expanding available information through new data collection and through record linkage are stressed. The relationship of nonexperimental data systems to randomized trials and to clinical decision-making is examined.
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When it is well conducted, a randomized clinical trial provides the strongest evidence available for evaluating the comparative effectiveness of the interventions tested. Over the last two generations, we have learned much about various devices for strengthening them and about methods of avoiding pitfalls in their design, execution, analysis, and reporting. ⋯ Because the controlled trial depends on an argument based on exclusion (i.e., no other causes or differences affected the experimental groups), we strengthen its inference by taking steps to exclude any such differences. This article discusses a number of issues that deserve consideration: problems and generalizability, devices for strengthening trials, issues of power and sample size, the relationship between study design and reported gains, when to undertake a trial, the role of collaborative trials, and ways to make trials more feasible in clinical settings.
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At present there is no definitive test for appendicitis and no clear set of signs and symptoms, so that diagnosis is uncertain and probabilistic. A computer model for analyzing clinical data can improve physician accuracy in diagnosing appendicitis by assessing the outcome probabilities associated with the treatment options. Should a definitive test become available, the computer model will aid clinicians in determining when to test. Once our proposed model has been validated, it will not only improve physician decision-making, but also provide quality assurance feedback, generate reports for documentation, and compile a data base of many cases for study and reference.
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Int J Technol Assess Health Care · Jan 1989
Test of a noninvasive instrument for measuring hemoglobin concentration.
A colorimetric instrument for the noninvasive quantification of hemoglobin, designed using color shades resembling those observed in the conjunctiva, was tested. The instrument's colors are contrasted against the color of the conjunctiva to measure hemoglobin content. Sensitivity, specificity, negative predictive value, and false-negative value were estimated to test the instrument's accuracy; kappa coefficients were used to estimate inter- and intraobserver variability. ⋯ The interobserver kappa coefficients for three pairs of readers were good to excellent for the same hemoglobin screening value. Statistically significant differences were noted, however, between observers during the reliability test. The instrument can be used by unskilled personnel to improve their decision-making about whom to send for further care or for supplementation with iron.