PDF《MARK》

Jacka et al., 2012;

Kim et al., 2015;

Miki et al., 2015), whereas no signi?cant association was found in other studies (Lehto et al., 2013;

Maserejian et al., 2012;

Vashum et al., 2014). For dietary iron intake, while a signi?cantly association with a decreased risk of depression was reported in two studies (Kim et al., 2015;

Miki et al., 2015), the signi?cant association was not found in one study (Woo et al., 2006). Therefore, we conducted a meta-analysis to systemically evaluate the associations between depression and dietary zinc and iron intake. 2. Materials and methods We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guideline in this meta-analysis (Moher et al., 2009). http://dx.doi.org/10.1016/j.psychres.2017.02.006 Received

17 October 2016;

Received in revised form

22 January 2017;

Accepted

2 February

2017 ? Corresponding author. E-mail addresses: [email protected], [email protected] (D. Zhang). Psychiatry Research

251 (2017) 41C47 Available online

03 February

2017 0165-1781/ ?

2017 Elsevier B.V. All rights reserved. MARK 2.1. Search strategy We searched PubMed, Embase, Web of Science, Chinese National Knowledge Infrastructure (CNKI) and Wanfang databases up to January 2017, with the following search terms '

zinc'

, '

iron'

, and '

depression'

, '

depressive disorder'

, '

depressive symptoms'

without re- strictions. We also reviewed the reference lists from retrieved articles to identify additional studies not captured by our database search. 2.2. Inclusion criteria We included studies that met the following criteria: (1) an observational study (cohort, case-control, cross-sectional) published as an original article;

(2) the exposure of interest was dietary zinc or iron intake;

(3) the outcome of interest was depression;

(4) available relative risk (RR) or odds ratio (OR) with 95% con?dence interval (CI) (or data to calculate these) was provided (we presented all results with RR for simplicity);

and (5) the study was conducted within the general population (postpartum depression, depression in pregnancy, diabetes, hypertension and other related diseases population were excluded). The most recent and complete article was chosen if a study had been published more than once. Two investigators searched articles and reviewed all retrieved studies independently. If the two investigators disagreed about the eligibility of an article, it was resolved by dialogue with a third investigator. 2.3. Data extraction The following data were extracted from each study by two inves- tigators independently: the ?rst author'

s name, publication year, country where the study was performed, study design, age range or mean age at baseline years, sex, sample size, the number of depression cases, dietary zinc or iron intake assessment methods, depression assessment methods, variables adjusted for in studies and the most adjusted RRs with 95% CIs of depression for dietary zinc or iron intake. 2.4. Statistical analysis Pooled measurement was calculated as the inverse variance- weighted mean of the logarithm of study-speci?c RRs to assess the associations between dietary zinc and iron intake and risk of depres- sion. The I2 of Higgins and Thompson was used to assess heterogeneity among studies (Higgins and Thompson, 2002) and I2 values of 0%, 25%, 50%, and 75% represent no, low, moderate, and high hetero- geneity, (Higgins et al., 2003) respectively. The DerSimonian and Laird random e?ects model (REM) was selected as the pooling method (Higgins et al., 2003). Meta-regression analyses were conducted to explore potential sources of heterogeneity. The in?uence analysis was performed with one study removed at a time to assess whether the results could have been a?ected markedly by a single study. Subgroup analyses by the continent, study design, dietary zinc assessment methods, depression assessment methods and adjustment for body mass index (BMI) were conducted. Publication bias was evaluated with visual inspection of the funnel plot and Egger'