Table 2

Sample size estimations

Total number scanned for amyloid=316
Number randomised=88
Number of completers=75 (=88×0.86)
Power estimate* assuming tau PET mean annual change (SD) of 0.05 (0.04)† when untreatedPower estimate* assuming tau PET mean annual change (SD) of 2.01 (2.97)‡ when untreated
One-year change from baseline in mean tau accumulation with semaglutideAlpha 0.05Alpha 0.10Alpha 0.05Alpha 0.10
20% lower compared with placebo. Effect differences of 0.01 and 0.402, respectively19.7%29.9%9.2%16.0%
30% lower compared with placebo. Effect differences of 0.015 and 0.603, respectively38.1%50.8%14.6%23.4%
40% lower compared with placebo. Effect differences of 0.02 and 0.804, respectively59.8%71.6%22.3%33.0%
  • 316 individuals need to be screened to randomise 88 participants, with 75 participants completing the study, assuming a 14% dropout rate.

  • *Power calculation is based on a two-sample t-test assuming equal variance.

  • †Hanseeuw, BJ et al.32 2019 PMID: 31157827.

  • ‡Whittington A, Gunn R.33 2021 PMID: 33517326.