The following analysis compares the estimated sample sizes necessary to detect change on various outcomes.
The first tab (dataset) provides descriptions of the data.
| Overall | |
|---|---|
| n | 65 |
| days_between_visit (mean (SD)) | 286.34 (82.04) |
| age_at_visit (mean (SD)) | 68.20 (7.42) |
| education (mean (SD)) | 15.69 (2.56) |
| sex_at_birth = M (%) | 37 (56.9) |
| ftldcdr_global (%) | |
| 0 | 1 ( 1.5) |
| 0.5 | 21 (32.3) |
| 1 | 28 (43.1) |
| 2 | 13 (20.0) |
| 3 | 2 ( 3.1) |
| genetic_status (%) | |
| MAPT | 2 ( 3.1) |
| NONE-Research genetic testing completed and no mutation identified | 48 (73.8) |
| OTHER-Variant of unknown significance | 3 ( 4.6) |
| Pending results | 12 (18.5) |
| moca_total (mean (SD)) | 21.32 (4.67) |
| psprs_totalcln (mean (SD)) | 29.64 (12.01) |
| ftldcdr_sob (mean (SD)) | 5.25 (3.88) |
| uds3_ef (mean (SD)) | -2.03 (0.80) |
| flu_animal (mean (SD)) | 11.59 (5.06) |
| flu_veg (mean (SD)) | 7.70 (3.49) |
| flu_fwords (mean (SD)) | 7.17 (4.24) |
| flu_lwords (mean (SD)) | 6.71 (3.71) |
| traila_ratio (mean (SD)) | 3.32 (2.41) |
| trailb_ratio (mean (SD)) | 13.60 (14.74) |
| dig_back_sum (mean (SD)) | 4.36 (1.90) |
| 0 | 0.5 | 1 | 2 | 3 | p | test | |
|---|---|---|---|---|---|---|---|
| n | 1 | 21 | 28 | 13 | 2 | ||
| days_between_visit (mean (SD)) | NaN (NA) | 310.45 (99.82) | 270.92 (69.39) | 261.46 (56.47) | 407.50 (26.16) | 0.038 | |
| age_at_visit (mean (SD)) | 80.00 (NA) | 68.38 (6.89) | 68.04 (6.54) | 70.15 (6.56) | 50.00 (7.07) | NA | |
| education (mean (SD)) | 18.00 (NA) | 15.81 (2.46) | 16.07 (2.43) | 14.46 (2.90) | 16.00 (2.83) | NA | |
| sex_at_birth = M (%) | 1 (100.0) | 11 (52.4) | 18 (64.3) | 6 (46.2) | 1 (50.0) | 0.698 | |
| genetic_status (%) | 0.002 | ||||||
| MAPT | 0 ( 0.0) | 0 ( 0.0) | 1 ( 3.6) | 0 ( 0.0) | 1 (50.0) | ||
| NONE-Research genetic testing completed and no mutation identified | 1 (100.0) | 18 (85.7) | 18 (64.3) | 11 (84.6) | 0 ( 0.0) | ||
| OTHER-Variant of unknown significance | 0 ( 0.0) | 0 ( 0.0) | 2 ( 7.1) | 0 ( 0.0) | 1 (50.0) | ||
| Pending results | 0 ( 0.0) | 3 (14.3) | 7 (25.0) | 2 (15.4) | 0 ( 0.0) | ||
| moca_total (mean (SD)) | 23.00 (NA) | 23.24 (3.46) | 21.70 (3.89) | 18.20 (5.49) | 8.00 (NA) | NA | |
| psprs_totalcln (mean (SD)) | 22.00 (NA) | 23.62 (10.01) | 30.21 (10.23) | 39.50 (8.98) | 50.50 (21.92) | NA | |
| ftldcdr_sob (mean (SD)) | 0.00 (NA) | 2.14 (0.95) | 4.86 (1.52) | 9.50 (2.28) | 18.50 (0.71) | NA | |
| uds3_ef (mean (SD)) | -1.07 (NA) | -1.86 (0.98) | -2.03 (0.72) | -2.32 (0.61) | -2.87 (NA) | NA | |
| flu_animal (mean (SD)) | 13.00 (NA) | 14.33 (5.55) | 11.22 (4.17) | 8.00 (3.50) | 3.00 (NA) | NA | |
| flu_veg (mean (SD)) | 10.00 (NA) | 9.42 (3.55) | 7.22 (3.03) | 6.11 (2.93) | 0.00 (NA) | NA | |
| flu_fwords (mean (SD)) | 11.00 (NA) | 8.63 (3.74) | 7.33 (4.33) | 4.45 (3.59) | 1.00 (NA) | NA | |
| flu_lwords (mean (SD)) | 9.00 (NA) | 7.61 (4.19) | 6.67 (3.73) | 5.27 (2.80) | 5.00 (NA) | NA | |
| traila_ratio (mean (SD)) | 0.96 (NA) | 2.85 (1.42) | 3.30 (2.61) | 4.63 (3.19) | NaN (NA) | NA | |
| trailb_ratio (mean (SD)) | 3.29 (NA) | 12.59 (12.88) | 12.94 (13.09) | 18.29 (22.03) | NaN (NA) | NA | |
| dig_back_sum (mean (SD)) | 5.00 (NA) | 4.42 (2.24) | 4.28 (1.67) | 4.67 (1.94) | 2.00 (NA) | NA |
Each analysis below is based on the change over time in the data set described above. A difference score was calculated (Visit 2 score - Visit 1 score). This difference was then annualized: [difference score / days between visits ] * 365. I also created a version of this where the raw scores were converted to Z scores based on baseline distributions. Then that z score was annualized. Therefore we have 3 variables of interest (and SD) based on units:
Raw score units: Difference (Diff SD)
Annualized units: Annualized decline (Ann. SD)
Annualized Z score: Annualized Z-Score Decline (Ann. Z. SD)
I calculated necessary sample size for each measure to detect a hypothetical drug effect that reduced decline by 30%. Power was set at .9 with an alpha of .05. Let me know if you want any other values here.
I completed analyses first in the full sample, then in sub samples that were closer to what would be in the actual trial. The tables below present the estimated sample sizes for:
Raw score units: SampleSize_RawUnits
Annualized units: SampleSize_ann
Annualized Z score: SampleSize_AnnZ
| Variable | Sample Size | Difference | Diff. SD | Annualized Decline | Ann. SD | Annualized Z-score Decline | Ann. Z. SD | SampleSize_rawunits | SampleSize_ann | SampleSize_annZ |
|---|---|---|---|---|---|---|---|---|---|---|
| psprs_totalcln | 43 | 9.302 | 12.118 | 12.996 | 18.728 | 1.034 | 1.490 | 141 | 172 | 172 |
| perscare | 61 | 0.525 | 0.744 | 0.729 | 1.070 | 0.925 | 1.359 | 167 | 179 | 179 |
| ftldcdr_sob | 61 | 1.869 | 3.063 | 2.482 | 4.396 | 0.634 | 1.124 | 223 | 260 | 260 |
| homehobb | 61 | 0.393 | 0.678 | 0.519 | 0.950 | 0.715 | 1.309 | 246 | 278 | 278 |
| memory | 61 | 0.213 | 0.442 | 0.284 | 0.640 | 0.574 | 1.296 | 357 | 422 | 422 |
| moca_total | 49 | -1.857 | 4.021 | -2.299 | 5.402 | -0.504 | 1.183 | 388 | 457 | 457 |
| traila_ratio | 42 | 1.477 | 3.679 | 1.969 | 4.875 | 1.091 | 2.700 | 514 | 508 | 508 |
| cdrlang | 61 | 0.254 | 0.681 | 0.328 | 0.973 | 0.596 | 1.767 | 595 | 727 | 727 |
| commun | 61 | 0.221 | 0.595 | 0.274 | 0.804 | 0.397 | 1.165 | 599 | 712 | 712 |
| flu_animal | 47 | -1.383 | 4.163 | -1.613 | 5.602 | -0.337 | 1.172 | 750 | 999 | 999 |
| judgment | 61 | 0.123 | 0.435 | 0.173 | 0.593 | 0.266 | 0.913 | 1034 | 978 | 978 |
| flu_veg | 49 | -0.714 | 2.630 | -0.918 | 3.764 | -0.267 | 1.093 | 1123 | 1393 | 1393 |
| trailb_ratio | 31 | 2.191 | 8.352 | 2.662 | 11.102 | 0.193 | 0.804 | 1204 | 1441 | 1441 |
| flu_fwords | 50 | -0.880 | 3.420 | -1.121 | 4.730 | -0.264 | 1.112 | 1251 | 1473 | 1473 |
| orient | 61 | 0.123 | 0.489 | 0.170 | 0.693 | 0.377 | 1.539 | 1308 | 1377 | 1377 |
| uds3_ef | 51 | -0.132 | 0.551 | -0.161 | 0.754 | -0.204 | 0.954 | 1444 | 1807 | 1807 |
| dig_back_sum | 47 | -0.404 | 1.861 | -0.601 | 2.534 | -0.302 | 1.275 | 1755 | 1474 | 1474 |
| flu_lwords | 49 | -0.612 | 2.971 | -0.550 | 4.649 | -0.145 | 1.222 | 1950 | 5917 | 5917 |
| comport | 61 | 0.016 | 0.619 | 0.006 | 0.993 | 0.008 | 1.422 | 118019 | 2345235 | 2345235 |
| Variable | Sample Size | Difference | Diff. SD | Annualized Decline | Ann. SD | Annualized Z-score Decline | Ann. Z. SD | SampleSize_rawunits | SampleSize_ann | SampleSize_annZ |
|---|---|---|---|---|---|---|---|---|---|---|
| psprs_totalcln | 36 | 9.889 | 12.547 | 13.922 | 19.248 | 1.275 | 1.763 | 133 | 158 | 158 |
| ftldcdr_sob | 46 | 2.120 | 3.072 | 2.809 | 4.361 | 1.489 | 2.311 | 174 | 200 | 200 |
| perscare | 46 | 0.543 | 0.808 | 0.742 | 1.153 | 1.766 | 2.746 | 183 | 200 | 200 |
| homehobb | 46 | 0.446 | 0.677 | 0.574 | 0.965 | 1.551 | 2.610 | 191 | 235 | 235 |
| memory | 46 | 0.217 | 0.360 | 0.291 | 0.550 | 0.849 | 1.601 | 227 | 295 | 295 |
| commun | 46 | 0.293 | 0.602 | 0.380 | 0.807 | 1.030 | 2.188 | 348 | 374 | 374 |
| trailb_ratio | 27 | 3.273 | 7.056 | 4.315 | 8.768 | 0.564 | 1.147 | 385 | 342 | 342 |
| moca_total | 39 | -1.974 | 4.264 | -2.417 | 5.732 | -0.738 | 1.750 | 386 | 466 | 466 |
| cdrlang | 46 | 0.293 | 0.663 | 0.372 | 0.879 | 0.876 | 2.071 | 423 | 463 | 463 |
| judgment | 46 | 0.174 | 0.411 | 0.242 | 0.563 | 0.546 | 1.271 | 463 | 449 | 449 |
| traila_ratio | 37 | 1.413 | 3.577 | 1.719 | 4.121 | 0.942 | 2.258 | 531 | 476 | 476 |
| flu_animal | 39 | -1.410 | 4.399 | -1.508 | 5.828 | -0.324 | 1.250 | 806 | 1236 | 1236 |
| flu_fwords | 41 | -1.098 | 3.639 | -1.425 | 5.029 | -0.348 | 1.228 | 910 | 1032 | 1032 |
| flu_veg | 41 | -0.707 | 2.695 | -0.878 | 3.688 | -0.258 | 1.082 | 1202 | 1461 | 1461 |
| uds3_ef | 41 | -0.129 | 0.582 | -0.153 | 0.806 | -0.187 | 0.981 | 1677 | 2284 | 2284 |
| orient | 46 | 0.098 | 0.442 | 0.151 | 0.670 | 0.603 | 2.672 | 1694 | 1627 | 1627 |
| flu_lwords | 40 | -0.675 | 3.214 | -0.482 | 5.004 | -0.123 | 1.278 | 1877 | 8930 | 8930 |
| dig_back_sum | 39 | -0.231 | 1.898 | -0.350 | 2.528 | -0.176 | 1.267 | 5602 | 4312 | 4312 |
| comport | 46 | 0.054 | 0.529 | 0.058 | 0.852 | 0.125 | 1.830 | 7858 | 17633 | 17633 |
| Variable | Sample Size | Difference | Diff. SD | Annualized Decline | Ann. SD | Annualized Z-score Decline | Ann. Z. SD | SampleSize_rawunits | SampleSize_ann | SampleSize_annZ |
|---|---|---|---|---|---|---|---|---|---|---|
| psprs_totalcln | 14 | 11.357 | 10.846 | 15.271 | 16.048 | 3.531 | 3.710 | 14 | 17 | 17 |
| ftldcdr_sob | 18 | 1.472 | 1.898 | 1.696 | 2.058 | 1.044 | 1.266 | 25 | 23 | 23 |
| memory | 18 | 0.167 | 0.243 | 0.207 | 0.318 | 0.697 | 1.071 | 32 | 36 | 36 |
| homehobb | 18 | 0.306 | 0.518 | 0.341 | 0.740 | 0.867 | 1.883 | 44 | 72 | 72 |
| perscare | 18 | 0.333 | 0.594 | 0.413 | 0.740 | 1.279 | 2.290 | 48 | 49 | 49 |
| judgment | 18 | 0.194 | 0.389 | 0.230 | 0.455 | 0.601 | 1.186 | 61 | 59 | 59 |
| flu_animal | 15 | -2.067 | 4.728 | -1.685 | 6.066 | -0.330 | 1.187 | 80 | 197 | 197 |
| commun | 18 | 0.222 | 0.521 | 0.276 | 0.623 | 0.754 | 1.702 | 84 | 78 | 78 |
| cdrlang | 18 | 0.167 | 0.454 | 0.127 | 0.486 | 0.334 | 1.281 | 113 | 224 | 224 |
| traila_ratio | 15 | 0.525 | 1.497 | 0.526 | 1.614 | 0.380 | 1.167 | 124 | 143 | 143 |
| trailb_ratio | 11 | 1.683 | 7.251 | 2.078 | 7.712 | 0.654 | 2.427 | 282 | 210 | 210 |
| flu_lwords | 16 | 0.688 | 3.497 | 1.574 | 5.479 | 0.344 | 1.198 | 394 | 184 | 184 |
| comport | 18 | 0.056 | 0.379 | 0.098 | 0.527 | 0.251 | 1.355 | 709 | 443 | 443 |
| orient | 18 | 0.028 | 0.208 | 0.004 | 0.273 | 0.018 | 1.183 | 854 | 65393 | 65393 |
| flu_veg | 16 | -0.312 | 2.575 | -0.237 | 3.477 | -0.072 | 1.059 | 1032 | 3262 | 3262 |
| dig_back_sum | 16 | 0.188 | 1.870 | 0.359 | 2.197 | 0.155 | 0.952 | 1512 | 571 | 571 |
| moca_total | 14 | -0.214 | 3.926 | -0.553 | 5.275 | -0.136 | 1.295 | 5105 | 1386 | 1386 |
| flu_fwords | 16 | -0.188 | 4.262 | -0.086 | 5.459 | -0.019 | 1.217 | 7857 | 61810 | 61810 |
| uds3_ef | 16 | -0.023 | 0.752 | 0.064 | 0.957 | 0.062 | 0.935 | 16168 | 3454 | 3454 |