Review articleBody mass index and risk of suicide: A systematic review and meta-analysis
Introduction
Suicide is defined as intentional deaths and self-inflicted deaths (WorldHealthOrganization, 1993). Accordingly, suicide is the 13th leading cause of death worldwide (Wang et al., 2012). The prevalence of suicide is estimated 11.4 per 100,000 population, which ultimately causes 804,000 suicides mortality around the world (Turecki and Brent, 2016). Compared with suicide mortality, suicide attempts are much more prevalent (Turecki and Brent, 2016). The past year prevalence of suicidal ideation 2.0% and 2.1% and for attempted suicide 0.3% and 0.4% are estimated in developed and developing countries respectively (Borges et al., 2010). One of the factors that could be involved in the suicide is BMI.
Obesity is one of the most prevalent health problem in present time (Finucane et al., 2011, Kelly et al., 2008). Measuring by the BMI, it is estimated that one third of the adult population worldwide is overweight (Lehnert et al., 2013). Over the past decades, the prevalence of obesity has increased dramatically (NCD, 2016), over the course of four decades, age-standardized prevalence of obesity increased from 3.2% in 1975 to 10.8% in 2014 for men and from 6.4% to 14.9% in women(NCD, 2016), and the prevalence of obesity in children and adolescences increased from 1975 to 2016 (NCD, 2017), age-standardized prevalence of obesity increased from 0.7% in 1975 to 5.6% in 2016 for girls and from 0.9% to 7.8% in boys (NCD, 2017). It's well-known that obesity and overweight are associated with disabilities and mortality (Bray and Bellanger, 2006, Lu et al., 2014). High weight has unfavorable consequences and 70% of deaths are associated with cardiovascular disease caused by high BMI (Afshin et al., 2017).
Extensive studies have been conducted to investigate the role of BMI in suicide, but the results of the studies are controversial, some studies have shown that BMI is inversely associated with suicide mortality (Bjerkeset et al., 2008, Carpenter et al., 2000, Kaplan et al., 2007, Magnusson et al., 2006, Mukamal et al., 2007, Mukamal et al., 2010, Zhang, 2006). Other studies also show a positive association among BMI and suicidal ideation (Brunner et al., 2006, Dong et al., 2006, Eaton et al., 2005, Falkner et al., 2001, Kim, 2011, Mather et al., 2009, Swahn et al., 2009, Whetstone et al., 2007). Two meta-analysis studies have also looked at the association between BMI and suicide (Klinitzke et al., 2013, Perera et al., 2016). The researchers showed that there is an inverse relationship between BMI and suicide mortality (Klinitzke et al., 2013, Perera et al., 2016). The study of Perera et al. (2016) includes cross-sectional, case control and cohort studies, therefore, due to the interference of other factors in cross-sectional and case control studies, accurate drawing of the relationship between BMI and suicide is difficult, and on the other hand, in this study, sex specified results were not reported in the relationship between BMI and suicide. In another meta-analysis, only 15 studies were included in meta-analysis (Klinitzke et al., 2013). Critical review of a meta-analysis (Klinitzke et al., 2013) revealed several points: first, in order to achieve a causal relationship, it is necessary to consider prospective studies, but previous meta-analysis (Klinitzke et al., 2013) only included 7 prospective studies in meta-analysis; secondly that, carrying out a meta-analysis on association between obesity and suicide, the relationship between overweight and suicide has been neglected; while in the studies which were done in this regard, the results of the association between overweight and suicide are also reported.
Therefore, the present study seeks to investigate the risk of suicide mortality, suicidal ideation and attempted suicide based on BMI (obesity and overweight). The present study also examines the role of BMI in suicide in both sexes as well as the conducted different subgroups analysis.
Section snippets
Protocol
This research was based on PRISMA (Moher et al., 2009) protocol.
Search strategy
A systematic review was carried out in PubMed, Scopus, PsycInfo and Google Scholar databases, which included the keywords listed in Appendix A. Searching was limited to studies published in English until December 2017.
Selection criteria
The criteria for entering studies into the meta-analysis include: 1) prospective-cohort studies; 2) obesity/overweight as exposure; 3) suicide mortality, attempted suicide and suicidal ideation as outcome; 4)
Study selection
All eligible studies that investigated the association among obesity/overweight and suicide mortality, attempted suicide and suicidal ideation were included in the study. The Flowchart of selected studies is indicated in Fig. 1. A total of 194 potential related studies were identified. Finally 15 studies (Batty et al., 2010, Bjerkeset et al., 2008, Elovainio et al., 2009, Gravseth et al., 2010, Henriksen et al., 2014, Jee et al., 2011, Kaplan et al., 2007, Magnusson et al., 2006, Mukamal
Contributors
Nothing to declare.
Funding
Nothing to declare.
Acknowledgements
Nothing to declare.
Conflict of Interest
None.
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