Table 10.
Comparison of methods for increasing power in clinical trials: sample sizes per arm required to detect a 25% reduction in atrophy with 80% power, 5% significance
| Outcome measure: MCI (AD) | |||||||
|---|---|---|---|---|---|---|---|
| Strategy | ADAS-cog | CDR- SB |
Whole brain |
Ventricular expansion |
Hippocampal volume |
Entorhinal complex |
Reference |
| Subject selection by multiple biomarker classifier |
<40 (<40) |
[86] | |||||
| No baseline adjustments, no aging | 149 (81) | 234 (118) | 201 (88) | [174] | |||
| Best baseline adjustments, no aging | 122 (68) | 167 (84) | 178 (74) | ||||
| No baseline adjustments, with aging | 739 (235) | 944 (254) | 648 (179) | ||||
| Best baseline adjustments, with aging | 605 (197) | 675 (181) | 573 (150) | ||||
| Aβ–42 <192 pg/mL | 141 | 225 | 467 | [160] | |||
| Normal elderly | |||||||
| APOE ε4 carrier | 224 | 222 | 703 | ||||
| Normal elderly | |||||||
| All MCI | 834 | 674 | [172] | ||||
| Screening in, best enrichment | 260* | 191† | |||||
| Screening out, best enrichment | 517* | 351‡ | |||||
| All MCI | 978 | 437 | 181 | 161 | 186 | 140 | [168] |
| APOE ε4 enrichment | 774 | 397 | 135 | 129 | 133 | 100 | |
| Atrophy enrichment | 458 | 191 | 141 | 121 | 107 | 67 | |
| All MCI | 375 | [154] | |||||
| Enrichment with Aβ–42 | 225 | ||||||
| QUARC entorhinal volume vs baseline | 131 (44) | [297] | |||||
| QUARC entorhinal volume vs Aβ negative controls |
293 (74) | ||||||
*
FDG-PET.
†
Hippocampal volume.
‡
11C-PiB-PET.