Cognitive composites for genetic frontotemporal dementia: GENFI-Cog

Table 3 Sample size per arm for a hypothetical clinical trial using different cognitive outcome measures

Outcome measures	*C9orf72*			*GRN*			*MAPT*
Outcome measures	ES 10%	ES 20%	ES 40%	ES 10%	ES 20%	ES 40%	ES 10%	ES 20%	ES 40%
Cognitive composite scores
Average composite	306	76	19	27	7	2	124	31	8
Weighted composite	214	53	13	53	13	3	90	23	6
Language
Camel and Cactus Test	4946	1237	309	292	73	18	357	89	22
Boston Naming Test	1109	277	69	213	53	13	223	56	14
Category fluency	1584	396	99	781	195	49	400	100	25
Attention and mental processing speed
Digit span forward	13,0210	32,553	8138	2677	669	167	17,773	4443	1111
Trail Making Test – part A	2272	568	142	45	11	3	69	17	4
Digit symbol	254	64	16	925	231	58	80	20	5
D-KEFS CWIT – colour naming	866	216	54	502	126	31	66	17	4
D-KEFS CWIT – word naming	19,224	4806	1202	3310	828	207	150	37	9
Executive functioning
Digit span backward	1724	431	108	840	210	52	26,218	6555	1639
Trail Making Test – part B	1275	319	80	25	6	2	81	20	5
D-KEFS CWIT – ink naming	61	15	4	70	17	4	26	7	2
Phonemic fluency	558	139	35	2229	557	139	161	40	10
Visuoconstruction
Benson figure copy	5911	1478	369	2119	530	132	6,282,036	1,570,509	392,627
Memory
Benson figure recall	1044	261	65	657	164	41	7611	1903	476
FCSRT free recall	1302	326	81	294	74	18	521	130	33
FCSRT total recall	1020	255	64	477	119	30	524	131	33
FCSRT delayed free recall	606	152	38	767	192	48	261	65	16
FCSRT delayed total recall	358	89	22	193	48	12	681	170	43
Social cognition
Facial Emotion Recognition Test	7570	1892	473	7805	1951	488	147	37	9

The sample size per arm was estimated as n = (1 − ρ^2)(2σ^2)/δ^2 f(α,β), where ρ is the correlation between baseline and follow-up measures of the outcome, σ is the standard deviation of the outcome in the CDR® plus NACC-FTLD 0.5 group, δ is the treatment effect (effect size multiplied by the difference in mean between CDR® plus NACC-FTLD 0.5 and 1 group), α is the significance level (0.05), and 1 − β is the power to detect a treatment effect (80%)
Abbreviations: C9orf72 chromosome 9 open reading frame 72, GRN progranulin, MAPT microtubule-associated protein tau, ES effect size as a proportion of the difference between the outcome in the CDR® plus NACC-FTLD 0.5 group and the outcome in the CDR® plus NACC-FTLD 1 group, D-KEFS CWIT Delis-Kaplan Executive Function System Colour-Word Interference Test, FCSRT Free and Cued Selective Reminding Test

ISSN: 1758-9193