TY  - JOUR
T1  - CSf biomarkers and incipient alzheimer disease in patients with mild cognitive impairment
AU  - Mattsson N, Zetterberg H, Hansson O, et al
Y1  - 2009/07/22
N1  - 10.1001/jama.2009.1064
JO  - JAMA
SP  - 385
EP  - 393
VL  - 302
IS  - 4
N2  - Context 
                  Small single-center studies have shown that cerebrospinal fluid (CSF) biomarkers may be useful to identify incipient Alzheimer disease (AD) in patients with mild cognitive impairment (MCI), but large-scale multicenter studies have not been conducted.Objective 
                  To determine the diagnostic accuracy of CSF β-amyloid1-42 (Aβ42), total tau protein (T-tau), and tau phosphorylated at position threonine 181 (P-tau) for predicting incipient AD in patients with MCI.Design, Setting, and Participants 
                  The study had 2 parts: a cross-sectional study involving patients with AD and controls to identify cut points, followed by a prospective cohort study involving patients with MCI, conducted 1990-2007. A total of 750 individuals with MCI, 529 with AD, and 304 controls were recruited by 12 centers in Europe and the United States. Individuals with MCI were followed up for at least 2 years or until symptoms had progressed to clinical dementia.Main Outcome Measures 
                  Sensitivity, specificity, positive and negative likelihood ratios (LRs) of CSF Aβ42, T-tau, and P-tau for identifying incipient AD.Results 
                  During follow-up, 271 participants with MCI were diagnosed with AD and 59 with other dementias. The Aβ42 assay in particular had considerable intersite variability. Patients who developed AD had lower median Aβ42 (356; range, 96-1075 ng/L) and higher P-tau (81; range, 15-183 ng/L) and T-tau (582; range, 83-2174 ng/L) levels than MCI patients who did not develop AD during follow-up (579; range, 121-1420 ng/L for Aβ42; 53; range, 15-163 ng/L for P-tau; and 294; range, 31-2483 ng/L for T-tau, P < .001). The area under the receiver operating characteristic curve was 0.78 (95% confidence interval [CI], 0.75-0.82) for Aβ42, 0.76 (95% CI, 0.72-0.80) for P-tau, and 0.79 (95% CI, 0.76-0.83) for T-tau. Cut-offs with sensitivity set to 85% were defined in the AD and control groups and tested in the MCI group, where the combination of Aβ42/P-tau ratio and T-tau identified incipient AD with a sensitivity of 83% (95% CI, 78%-88%), specificity 72% (95% CI, 68%-76%), positive LR, 3.0 (95% CI, 2.5-3.4), and negative LR, 0.24 (95% CI, 0.21-0.28). The positive predictive value was 62% and the negative predictive value was 88%.Conclusions 
                  This multicenter study found that CSF Aβ42, T-tau, and P-tau identify incipient AD with good accuracy, but less accurately than reported from single-center studies. Intersite assay variability highlights a need for standardization of analytical techniques and clinical procedures.
SN  - 0098-7484
M3  - doi: 10.1001/jama.2009.1064
UR  - http://dx.doi.org/10.1001/jama.2009.1064
ER  -