Sensitivity to change and prediction of global change for the Alzheimer’s Questionnaire

Table 2 Sensitivity to change comparison for the AQ, FAQ, and MMSE in amnestic mild cognitive impairment, Alzheimer’s disease, and cognitively normal cases

Group	Instrument	Mean change	SD of mean change	95% CI of mean change	Pooled SD	ES	Reliability	d	Required sample size ^a
aMCI
	AQ	1.66	4.96	(0.40, 2.92)	6.10	0.27	0.65	0.33	251
	FAQ	2.05	5.79	(0.54, 3.56)	3.29	0.30	0.63	0.35	224
	MMSE	-0.55	2.54	(-1.19, 0.10)	2.47	0.22	0.56	0.24	597
AD
	AQ	2.49	4.77	(0.94, 4.03)	6.75	0.37	0.64	0.43	232
	FAQ	3.59	4.91	(2.00, 5.18)	5.36	0.52	0.81	0.84	119
	MMSE	-2.13	3.35	(-3.23, -1.03)	6.34	0.34	0.79	0.52	157
CN
	AQ	0.47	2.73	(-0.07, 1.00)	3.37	0.14	0.69	0.18	340
	FAQ	0.33	1.80	(-0.03, 0.69)	3.29	0.11	0.73	0.15	300
	MMSE	0.05	1.71	(-0.29, 0.39)	2.47	0.02	0.41	0.02	660

^aNumber of subjects per arm based on a 25% treatment effect of the mean change at 80% power with a two-tailed significance level of 0.05; sample size estimates are based on a two-year study for AD, a three-year study for aMCI, and five-year study for CN; for AQ and FAQ positive mean change scores represent increased impairment over time and negative mean change scores for MMSE also represent increased impairment over time. Effect size values are reported in absolute values and represent the magnitude of the difference for Year 2 scores subtracted from Year 1 scores. AD, Alzheimer’s disease; aMCI, amnestic mild cognitive impairment; AQ, Alzheimer’s Questionnaire; 95% CI, 95% confidence interval; CN, cognitively normal; d, effect size corrected for reliability; ES; effect size using pooled standard deviation; FAQ, Functional Activities Questionnaire; MMSE, Mini Mental State Exam; SD, standard deviation.

ISSN: 1758-9193