Association between body mass index and suicidal behaviors: a systematic review protocol

BACKGROUND: Suicide is among the leading causes of death worldwide. Suicide attempts and suicidal ideation are more common than completed suicide and are associated with psychological distress. These behaviors are considered risk factors of completed suicide. Considering the psychosocial stigma and medical comorbidities associated with obesity, an accumulating body of studies have investigated body mass index (BMI) as a potential risk factor of suicide. However, several cohort studies have demonstrated an inverse relationship between BMI and completed suicide, suggesting a protective effect of increasing BMI against completed suicide. The association between BMI and attempted suicide is more equivocal, with several studies reporting both positive and negative relationships between BMI and attempted suicide. The primary objective of this study is to systematically review the literature to determine the association between BMI and suicidal behavior (including completed suicide, attempted suicide, suicidal ideation) in an adult population (18 years and older). The secondary objective is to explore whether sex, age, and the method used in suicide modify the relationship between BMI and suicidal behavior. METHODS/DESIGN: An electronic search will be conducted using PubMed/MEDLINE, PsycINFO, CINAHL, and EMBASE using a predefined search strategy; databases will be searched from their inception. Two authors (SP and RE) will independently screen articles using predefined inclusion and exclusion criteria and will extract pertinent data using a pilot tested extraction form. At all levels of screening, discrepancies between the two authors will be resolved by consensus, and in the case of disagreement, by consulting a third author (ZS). The primary outcomes include the association between BMI and completed suicide, attempted suicide, and suicidal ideation. If appropriate, a meta-analysis will be conducted. Risk of bias and quality of evidence will be assessed. DISCUSSION: The results of this systematic review will inform health care professionals and researchers about whether BMI has a significant role in suicidal behavior and psychological well-being. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42014014739. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13643-015-0038-y) contains supplementary material, which is available to authorized users.