Table 3.

Characteristics and efficacy results of meta-analyses included

Study	Studies included	Number of patients	Selection criteria	Efficacy results; n (95% CI)	p-value
Zhou et al²³	Two clinical trials: Simons 2002; Sparks 2005	107	Patients with dementia or AD; randomised controlled trials	ADAS-Cog: 1.84 (–1.58, 5.27)	0.055
Gizachew et al²⁴	Four clinical trials	1,153	Clinical trials and subjects with a history or risk of AD	ADAS-Cog: –0.57 (–1.39, 0.25)	0.17
				MMSE: 0.57 (–0.36, 1.50)	0.23
				NPI: –0.77 (–1.59, 0.06)	0.07
	Six observational studies	21,819	Patients diagnosed with AD or at risk for the disease	HR: 0.69 (0.542, 0.882)	0.003
				OR: 0.447 (0.229, 0.668)	<0.001
Sun et al²⁵	Two clinical trials: Sparks 2005; Feldman 2010	710	Patients with probable AD; randomised placebo-controlled clinical trials. Sparks 2005: single-centre study; Feldman 2010: multi-centre study	ADAS-Cog: 1.05 (–3.06, 6.05)	0.52
				MMSE: 0.77 (–0.57, 2.10)	0.26
				CGIC: 0.13 (–0.15, 0.40)	0.38
				NPI: 2.07 (–1.59, 5.73)	0.27
Pandey et al²⁶	Five clinical trials: PROSPER 2002; Simons 2002; Sparks 2005; Feldman 2008; Sano 2011	6,958	Randomised clinical trials; subjects with a history or risk of AD	ADAS-Cog: –0.18 (–1.03, 0.66)	ns
				MMSE: –0.921 (–1.84, 0.0055)	<0.05
				CGIC: –0.26 (–3.11, 2.58)	ns
Richardson et al²⁷	14 AD studies		Patients; randomised controlled trials
	10 cohort studies	759,553	Cohort study	RR: 0.79 (0.63, 0.99)
	Three case-control studies	5,758	Case-control study	OR: 0.56 (0.41, 0.78)
	One cross-sectional study	57,104	Cross-sectional study	OR: 0.45 (0.35, 0.58)
McGuiness et al²⁸	Four clinical trials: Sparks 2005; Feldman 2010; Simons 2002; Sano 2011	1154	Patients with probable AD; clinical trials placebo controlled, randomised, double blind	ADAS Cog: –0.26 (–1.05, 0.52)	0.51
				MMSE: –0.32 (–0.71, 0.06)	0.099
				CGIC: –0.02 (–0.14, 0.10)	0.74
				NPI: –0.84 (–1.64, –0.05)	0.034

AD = Alzheimer's disease; ADAS-Cog = Alzheimer's disease assessment scale-cognitive; CGIC = Clinical Global Impressions of Change; CI = confidence interval; HR = hazard ratio; MMSE = mini-mental state examination; NPI = neuropsychiatric inventory; ns = non-significant; OR = odds ratio; RR = relative risk