Dong Y, et al. – For this meta–analysis, the clinicians aimed to assess the relationship between serum vitamin E and the risk of Alzheimer disease (AD). They concluded that Alzheimer disease was related to a low concentration of serum vitamin E in older people.

Methods

• For the purpose of this investigation, potentially relevant studies were chosen through PubMed, Embase, Wanfang, Chongqing VIP, and China National Knowledge Infrastructure databases by utilizing the core terms Vitamin E/alpha-tocopherol and Alzheime's disease/senile dementia/AD in the titles, abstracts, and keywords of the articles.
• The relationship between serum vitamin E levels and AD was estimated by utilizing the weighted mean difference (WMD) and 95% confidence interval by adopting a random effects model.
• By using Cochran Q test and I2 statistic, heterogeneity was evaluated.
• Forest plot was utilized to show the outcomes graphically from meta-analysis.
• Publication bias was assessed by utilizing funnel plots and Egger test.

Results

• Seventeen studies were identified that met the eligibility criteria.
• The examinations included two thousand fifty seven subjects with 904 AD patients and 1153 controls.
• The findings demonstrated that AD patients had a lower concentration of serum vitamin E compared with healthy controls among older people (WMD = -6.811 μ mol/L, 95% confidence interval -8.998 to -4.625; Z = -6.105, P < .001).
• Publication bias was not identified and sensitivity analysis performed by omitting each study, and calculating the pooled WMD again for the remaining studies showed the outcomes stable.