A diagnostic test is used to help determine whether a patient has a disease at the time the test is performed. Step 1: Developing the Review Topic and Frameworkĭeveloping the review topic, which includes the framework for thinking about the relationship between the test and patient outcomes and the key questions, can be fundamentally different for diagnostic and prognostic tests. However, important differences between diagnostic and prognostic tests that should be considered when planning and conducting a review are highlighted here. These steps include: (1) using the population, intervention, comparator, outcomes, timing and setting (PICOTS) typology and an analytic framework to develop the topic and focus the review on the most important key questions (2) conducting a thorough literature search (3) assessing the quality of reported studies (4) extracting and summarizing various types of statistics from clinical trials and observational studies and (5) meta-analyzing study results. Generally speaking, the steps for reviewing evidence for prognostic tests are similar to those used in the review of a diagnostic test and are discussed in other papers in this Medical Test Methods Guide. This paper is meant to complement the Evidence-based Practice Centers’ Methods Guide for Comparative Effectiveness Reviews, and is not a comprehensive or detailed review of methods that could be used to conduct a systematic review of a prognostic test. The questions that are most salient for clinical practice, and hence a systematic review, concern the accuracy of predictions derived from a test or prediction model, and how the results affect patient management and outcomes. Such reviews can serve to summarize available evidence, as well as guide further research regarding the usefulness of the tests. The plethora of potential new prognostic tests and prediction models, like treatments and diagnostic tests, are appropriate topics for systematic reviews. Some of these measures, singly or in combination as a prediction model, can be clinically useful. With increasing frequency, multiple objective measures of normal or pathologic biological processes as well as measures of social, psychological, behavioral, and demographic features are being associated with important patient outcomes. However, review of studies of the association between a potential prognostic test and patient outcomes would have little impact other than to determine whether further development as a prognostic test might be warranted. Reclassification tables can help determine how a prognostic test affects the classification of patients into different prognostic groups, and hence helps determine their treatment. The outcome probabilities or level of risk and other characteristics of prognostic groups are the most salient statistics for review and perhaps meta-analysis. The proposed use of a prognostic test should serve as the framework for a systematic review and help define the key questions. ![]() We provide suggestions for those interested in conducting systematic reviews of a prognostic test. Exemplary reviews of prognostic tests are not widely available, and the methods used to review diagnostic tests do not necessarily address the most important questions about prognostic tests that are used to predict the time-dependent likelihood of future patient outcomes. Systematic reviews of this growing literature can help determine whether the available evidence supports use of a new biomarker as a prognostic test that can more accurately place patients into different prognostic groups to improve treatment decisions and the accuracy of outcome predictions. AbstractĪ number of new biological markers are being studied as predictors of disease or adverse medical events among those who already have a disease. ![]() This is a chapter from AHRQ's Methods Guide for Medical Test Reviews.
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