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Table 2 Sample size calculation based on the observed mean decline of the sum score within 1 year

From: A language-based sum score for the course and therapeutic intervention in primary progressive aphasia

Treatment effect All PPA nfvPPA svPPA lvPPA
Mean decline N per group Mean decline N per group Mean decline N per group Mean decline N per group
Balanced sum score
 10% –4.35 690 –5.82 712 –3.4 1815 –3.48 709
 20% –8.7 173 –11.63 178 –6.8 454 –6.97 178
 30% –13.04 77 –17.45 80 –10.19 202 –10.45 79
 40% –17.39 44 –23.26 45 –13.59 114 –13.94 45
 50% –21.74 28 –29.08 29 –16.99 73 –17.42 29
 60% –26.09 20 –34.9 20 –20.39 51 –20.9 20
 70% –30.44 15 –40.71 15 –23.79 38 –24.39 15
 80% –34.78 11 –46.53 12 –27.18 29 –27.87 12
 90% –39.13 9 –52.34 9 –30.58 23 –31.36 9
 100% –43.48 7 –58.16 8 –33.98 19 –34.84 8
Unbalanced sum score
 10% –2.66 1110 –3.53 913 –2.14 1674 –2.32 963
 20% –5.33 278 –7.06 229 –4.28 419 –4.64 241
 30% –7.99 124 –10.59 102 –6.42 186 –6.96 107
 40% –10.66 70 –14.12 58 –8.56 105 –9.28 61
 50% –13.32 45 –17.65 37 –10.71 67 –11.61 39
 60% –15.98 31 –21.17 26 –12.85 47 –13.93 27
 70% –18.65 23 –24.7 19 –14.99 35 –16.25 20
 80% –21.31 18 –28.23 15 –17.13 27 –18.57 16
 90% –23.98 14 –31.76 12 –19.27 21 –20.89 12
 100% –26.64 12 –35.29 10 –21.41 17 –23.21 10
  1. Percent values indicate a reduction in cognitive decline, the required number of cases per group (N per group) corresponds to verum and placebo
  2. The power was set to 80%, and the alpha error level to 5% for the use of a unpaired t test
  3. nfvPPA (N = 27), svPPA (N = 16), lvPPA (N = 12)
  4. lvPPA logopenic variant primary progressive aphasia, nfvPPA nonfluent variant primary progressive aphasia, svPPA semantic variant primary progressive aphasia