TABLE 3.

Sample size estimation for detecting intervention effects based on unselected MCI-Aβ+ subject or on SVR selection of at-risk subjects (defined as falling above the median of SVR scores)

		Main effect of time on cognitive changes in MCI-Aβ+				Required N per arm to detect an intervention effect of
Cognitive test	Group selection	β	T	P	Partial R2	10%	20%	30%	40%	% Reduction of required N
1-year follow-up
ADNI-MEM	No selection	−0.052	−4.021	<0.0001	0.010	18984	4301	1737	892	NA
	G-risk	−0.084	−4.703	<0.0001	0.028	6937	1572	635	327	63%
	AG-risk	−0.090	−5.170	<0.0001	0.033	5742	1301	526	271	70%
	AGC-risk	−0.095	−5.574	<0.0001	0.037	4940	1120	458	233	74%
	AFGC-risk	−0.109	−6.744	<0.0001	0.053	3375	765	310	159	82%
ADAS13	No selection	0.037	1.764	0.0792	0.002	94800	21475	8672	4453	NA
	G-risk	0.070	2.317	0.0224	0.008	27638	6261	2529	1299	71%
	AG-risk	0.073	2.326	0.0219	0.009	27392	6205	2506	1287	71%
	AGC-risk	0.089	2.933	0.0041	0.013	17335	3927	1586	815	82%
	AFGC-risk	0.100	3.149	0.0021	0.016	15086	3418	1381	709	84%
2-year follow-up
ADNI-MEM	No selection	−0.076	−6.425	<0.0001	0.026	9166	2077	839	431	NA
	G-risk	−0.131	−8.071	<0.0001	0.080	2741	622	252	130	70%
	AG-risk	−0.136	−8.372	<0.0001	0.085	2574	584	236	122	72%
	AGC-risk	−0.140	−8.862	<0.0001	0.095	2370	538	218	112	74%
	AFGC-risk	−0.144	−8.850	<0.0001	0.097	2293	520	211	109	75%
ADAS13	No selection	0.122	6.421	<0.0001	0.031	8748	1982	801	412	NA
	G-risk	0.178	6.208	<0.0001	0.060	4360	988	400	206	50%
	AG-risk	0.178	6.137	<0.0001	0.060	4545	1030	417	214	48%
	AGC-risk	0.199	6.957	<0.0001	0.075	3526	799	323	166	60%
	AFGC-risk	0.209	7.160	<0.0001	0.081	3410	773	313	161	61%
4-year follow-up
ADNI-MEM	No selection	−0.173	−10.755	<0.0001	0.107	3857	874	354	182	NA
	G-risk	−0.264	−12.331	<0.0001	0.250	1348	306	124	64	65%
	AG-risk	−0.291	−14.188	<0.0001	0.307	905	206	84	43	76%
	AGC-risk	−0.294	−14.303	<0.0001	0.318	900	205	83	43	76%
	AFGC-risk	−0.264	−12.694	<0.0001	0.256	1295	294	119	62	66%
ADAS13	No selection	0.239	10.750	<0.0001	0.118	3818	866	350	180	NA
	G-risk	0.325	10.943	<0.0001	0.222	1778	404	163	84	53%
	AG-risk	0.356	11.921	<0.0001	0.348	1462	332	135	69	62%
	AGC-risk	0.369	11.919	<0.0001	0.262	1441	327	133	68	62%
	AFGC-risk	0.338	11.302	<0.0001	0.235	1728	392	159	82	54%