To the Editor: Brandel et al.1 described the effect of different clinical criteria on incidence estimates for sporadic Creutzfeldt–Jakob disease (CJD): accepting either 14-3-3 protein positivity in CSF or an EEG showing periodic complexes as one of the criteria for suspected CJD in either the French or European criteria resulted in a slight increase in estimated incidence. They also compared test performance characteristics of different traditional diagnostic criteria for CJD, but did not compare modifications incorporating 14-3-3 protein results. Therefore, I analyzed the authors’ results to calculate gain in diagnostic certainty and other performance characteristics2,3⇓ attributable to incorporation of 14-3-3 protein results into the French or European criteria for probable CJD (additional information can be found on the Neurology Web site; go to www.neurology.org). Inclusion of 14-3-3 protein results improved sensitivity, without a loss of specificity, for both the French and European criteria. Because the false negative rate decreased markedly, both the predictive value of a negative test and gain in diagnostic certainty for a negative test improved significantly. I evaluated two possible further modifications of the criteria, which differ in the weight given to the 14-3-3 protein results: in one, 14-3-3 protein results are considered to be of equal importance to the combination …