Table 3.

Sample size per treatment arm needed to obtain 20% reduction in the slope, for α = 0.05 and β = 0.2, estimated via a simulation algorithm in MCI patients with abnormal CSF Aβ 1-42 concentration (MCI ABETA+) or positive to hippocampal atrophy (MCI HIPPO+). In both MCI groups, sample size decreased with increasing follow-up time for all biomarkers, irrespective of biomarker assessment frequency, and MR measures required lowest sample size. For all time sets, sample size was higher in MCI HIPPO+ than in MCI ABETA+ group (all biomarkers but hippocampal volume).

		T0-T6-T12-T18-T24	T0-T6-T12-T18	T0-T6-T12	T0-T12-T24
MCI ABETA+	ADAS-cog	568	>1000	>1000	991
	logPALZ	326	507	>1000	343
	HCI	175	263	512	185
	MetaROI	562	865	>1000	680
	Hipp. volume	102	144	282	112
	KN-BSI	46	54	78	48
MCI HIPPO+	ADAS-cog	>1000	>1000	>1000	>1000
	logPALZ	367	792	>1000	468
	HCI	198	263	532	204
	MetaROI	649	>1000	>1000	969
	Hipp. volume	84	120	188	99
	KN-BSI	77	87	117	85

ADAS-cog=Alzheimer's Disease Assessment Scale-cognitive subscale; logPALZ=log-transformed PMOD Alzheimer score ¹⁶; HCI=hypometabolic convergence index ¹⁷; MetaROI=FDG-PET summary metric based on meta-analitically derived regions of interest reflecting AD hypometabolism pattern ¹⁸; Hipp. volume=hippocampal volume automatically computed by Freesurfer algorithm; KN-BSI=brain atrophy rate measured by KN boundary shift integral technique ²¹; T0=baseline, Tn=n-month follow-up.