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. Author manuscript; available in PMC: 2013 Sep 23.
Published in final edited form as: J Alzheimers Dis. 2013 Jan 1;36(3):475–486. doi: 10.3233/JAD-122212

Figure 2.

Figure 2

Sample sizes required for clinical trials with 80% power to detect a treatment effect on risk of progression to probable AD dementia by Cox regression based on survival curves estimated from the NACC-UDS cohort for all non-demented subjects (A) and CDR 0.5 non-demented subjects only (B) comparing all subjects (dashed line) with those meeting the PPG-defined mid-risk criteria (solid line). Estimates assume 1:1 randomization, one year accrual, two years minimal follow-up, and two-tailed testing at alpha = 0.05.