, Department of Biostatistics, University of Texas MD Anderson Cancer Center, Houston, TX, 77230, U. negative: intensive care unit admissions, 0.751 vs. For those with critical illness, maximum SOFA score accuracy at critical illness onset also did not differ by COVID-19 status (AUROC, COVID-19 positive vs. 2015 Nov 04 ĭivision of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN, 55455, U. P 0.15) admissions but was slightly better calibrated in patients who were positive for COVID-19. The small sample properties of the proposed group sequential testing procedures and estimators are evaluated by simulation, and we illustrate our approach in the context of a study to validate a novel biomarker for prostate cancer. We then discuss how our results can be combined with standard group sequential methods to develop group sequential testing procedures and bias-adjusted estimators for the PPV and NPV curve. First, we develop asymptotic theory for the sequential empirical PPV and NPV curves when the prevalence must be estimated, rather than assumed known in a case-control study. A screen positive result means that you are in a group with an increased likelihood of having a baby with an open neural tube defect. In this paper, we consider group sequential testing of the predictive accuracy of a continuous biomarker with unknown prevalence. power due to sequential testing, so that the same level of power (.89) can be achieved by. Previously, we derived the asymptotic properties of the sequential empirical positive predictive value (PPV) and negative predictive value (NPV) curves, which summarize the predictive accuracy of a continuous marker, under case-control sampling.Ī limitation of this approach is that the prevalence cannot be estimated from a case-control study and must be assumed known. The selected DNA concentration cutoff value of 6♰ ng/mL fit the pre-defined test criteria, yielding a negative predictive value of 91 (95 CI 8793 26 of 297 samples), and a positive predictive value of 66 (6075 152 of 232). or predictive power after an interim analysis is very low. Group sequential testing procedures have been proposed as an approach to conserving resources in biomarker validation studies. Group sequential testing of the predictive accuracy of a continuous biomarker with unknown prevalence
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