Background: We conducted a systematic review and meta-analysis to determine the association between serum lipid levels and suicidality, as evidence from previous studies has been inconsistent. Methods: We identified relevant studies by searching Medline, Web of Science, EMBASE, and the Cochrane Database of Systematic Reviews (1980 to Dec. 5, 2014). Studies assessing the association between serum total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and/or triglycerides (TG) levels and suicidality were included. We used a random-effects model to take into account heterogeneity among studies. Results: We included 65 studies with a total of 510 392 participants in our analysis. Compared with the nonsuicidal patients, suicidal patients had significantly lower serum TC (weighted mean difference [WMD] −22.35, 95% confidence interval [CI] −27.95 to −16.75), LDL-C (WMD −19.56, 95% CI −26.13 to −12.99) and TG (WMD −23.40, 95% CI −32.38 to −14.42) levels, while compared with the healthy controls, suicidal patients had significantly lower TC (WMD −24.75, 95% CI −27.71 to −21.78), HDL-C (WMD −1.75, 95% CI −3.01 to −0.48) and LDL-C (WMD −3.85, 95% CI −7.45 to −0.26) levels. Furthermore, compared with the highest serum TC level category, a lower serum TC level was associated with a 112% (95% CI 40%–220%) higher risk of suicidality, including a 123% (95% CI 24%–302%) higher risk of suicide attempt and an 85% (95 CI 7%–221%) higher risk of suicide completion. The cut-off values for low and high serum TC level were in compliance with the categories reported in the original studies. Limitations: A major limitation of our study is the potential heterogeneity in most of the analyses. In addition, the suicidal behaviour was examined using different scales or methods across studies, which may further explain heterogeneity among the studies. Conclusion: We identified an inverse association between serum lipid levels and suicidality. More mechanistic studies are needed to further explain this association.

Studies that investigated the association between socio-economic position (SEP) and obesity in children suggest inconsistent results. The aim of this study is to summarize and quantify the current evidence on SEP and risks of overweight and obesity in children aged 0–15 years. Relevant studies published between 1990 to Sep 4, 2014 were searched in Medline, Web of Science, Embase and the Cochrane Database of Systematic Reviews. Risk estimates from individual studies were pooled using random-effects models, according to lowest vs the highest SEP category. A total of 62 articles were included in the meta-analysis. The odds of both overweight risk and obesity risk were higher in the children with lowest SEP than in those with highest SEP (OR, 1.10, 95% CI: 1.03–1.17 and OR, 1.41, 95% CI: 1.29–1.55, respectively). Sub-group analyses showed that the inverse relationships between SEP and childhood overweight and obesity were only found in high-income countries and in more economic developed areas. In conclusion, our study suggests that children with lower SEP had higher risks of overweight and obesity and the increased risks were independent of the income levels of countries.