A number of new biological markers are being studied as predictors of disease or adverse medical events among those who already have a disease. 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. 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. We provide suggestions for those interested in conducting systematic reviews of a prognostic test. The proposed use of the prognostic test should serve as the framework for a systematic review and to help define the key questions. The outcome probabilities or level of risk and other characteristics of prognostic groups are the most salient statistics for review and perhaps meta-analysis. Reclassification tables can help determine how a prognostic test affects the classification of patients into different prognostic groups, hence their treatment. 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.
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Acknowledgments: This work was partially funded by the Agency for Healthcare Research and Quality, U.S. Department of Health and Human Services contract number 290-207-10064 (EPC III) awarded to the Minnesota Evidence-based Practice Center and supported by VA Health Service Research and Development Grant HFP-98-001 for the Minneapolis Health Services Research Center of Excellence, the Center for Chronic Disease Outcomes Research. The authors are responsible for the content. The expressed views are the authors’ and do not necessarily represent the Agency for Healthcare Research and Quality, the U.S. Department of Health and Human Services, or the Department of Veterans Affairs.
- predictive accuracy