[Usefulness of the 14-3-3 test for the diagnosis of sCJD evaluated by a Spanish reference center]

The performance of the 14-3-3 protein test has been shown to be adequate for sporadic Creutzfeldt-Jakob disease (sCJD) diagnosis in selected populations, but its routine validity has been questioned.

One thousand and sixty-eight patients with clinically suspected sCJD were analyzed in a Spanish reference center. In order to explore the influence of the clinical context on the performance of the immunoassay, the patients were classified at sample reception according to the World Health Organization (WHO) diagnostic criteria excluding the 14-3-3 test results. The yield of the immunoassay was evaluated in each subgroup with criteria of probable, possible sCJD or non-sCJD.

In the set of patients with suspicion of sCJD the inclusion of the 14-3-3 test produces a significant increase in the diagnosis certainty (positive likelihood ratio: 10.1) compared to the WHO's criteria, excluding the 14-3-3 test. For patients classified at sample reception as probable sCJD (n=166), possible sCJD (n=129) and non-sCJD (n=773), the positive predictive values for the test were 98.4%, 97.5% and 31%, and the negative predictive values were 22.2%, 73.4% and 100%, respectively.

The predictive values of the assay vary according to the previous diagnostic certainty. Therefore, in order to interpret correctly the test, it is necessary to evaluate the degree of initial clinical suspicion of the patient at the moment of the cerebrospinal fluid (CSF) extraction. This study offers up-to-date information, referenced to the Spanish population, and in useful format, and it is intended to serve as a guideline for 14-3-3 test results interpretation to the clinicians in our community.