Figure 3. Survival Curves Reflecting Time From Positron Emission Tomography (PET) Scan to Mild Cognitive Impairment (MCI) Classification for the 4 Biomarker Groups, Across Cohorts.

The temporal meta–region of interest was used to define tau positivity (T+). Concordance values and SE are reported for the Cox regression models, which included age at the time of tau PET, sex, education, and APOE e4 status as covariates. Hazard ratios (HRs) for the PET biomarker groups are in reference to the amyloid-positive, tau-positive (A+T+) group. Inverted HRs are reported for ease of interpretation (ie, reflecting risk of progression to MCI in the A+T+ group relative to the other groups). The A−T+ group is displayed for visualization purposes but was not included in statistical analysis because of the small sample size. ADRC indicates Alzheimer Disease Research Center; AIBL, Australian Imaging, Biomarker & Lifestyle study; HABS, Harvard Aging Brain Study; PREVENT-AD, Pre-symptomatic Evaluation of Experimental or Novel Treatments for Alzheimer Disease study.

^aP < .05.

^bP < .01.

^cP < .001.