Background It is 10 years since the detection of cerebrospinal fluid (CSF) 14-3-3 was included in the diagnostic criteria for sporadic Creutzfeldt–Jakob disease (sCJD) by the WHO. Since that time, other CSF proteins, such as S100b and tau protein, have been proposed as surrogate markers for sCJD. The authors aimed to investigate the diagnostic value of each of these three proteins.

Methods CSF samples collected from patients who were referred to the National CJD Surveillance Unit as suspected cases of sCJD during the period 1997–2007 were analysed for 14-3-3, S100b and tau protein. The sensitivity, specificity, positive predictive value and negative predictive value of each of these markers, either alone or in combination for the diagnosis of sCJD, were assessed. The impact of CSF 14-3-3 analysis on the case classification of sCJD was investigated.

Results and discussion CSF 14-3-3 had the greatest sensitivity (86%) when compared with tau protein (81%) and S100b (65%). The combination of a positive CSF 14-3-3 or an elevated tau protein with a raised S100b had the highest positive predictive power for sCJD. During the study period, 100 patients were classified as probable sCJD solely on the basis of the clinical features and a positive CSF 14-3-3. The most sensitive marker for sCJD was a positive CSF 14-3-3. The analysis of CSF 14-3-3 plays a crucial role in the case classification of sCJD.