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
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.


CONCLUSIONS
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.


BACKGROUND
PROSPERO CRD42014014739 .
Health Research Methodology Graduate Program, McMaster University, 1280 Main Street W, Hamilton, ON, L8S 4L8, Canada. pererasm@mcmaster.ca.|Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. pererasm@mcmaster.ca.
Stefan
S
Perera
MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street W., Hamilton, ON, L8S 4L8, Canada. eisenrb@mcmaster.ca.
Rebecca
R
Eisen
MiNDS Neuroscience Graduate Program, McMaster University, 1280 Main Street W., Hamilton, ON, L8S 4L8, Canada. baworm@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. baworm@mcmaster.ca.
Monica
M
Bawor
Health Research Methodology Graduate Program, McMaster University, 1280 Main Street W, Hamilton, ON, L8S 4L8, Canada. dennisbb@mcmaster.ca.|Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. dennisbb@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. dennisbb@mcmaster.ca.
Brittany
B
Dennis
Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. rdesouz@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. rdesouz@mcmaster.ca.
Russell
R
de Souza
Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. thabanl@mcmaster.ca.|Biostatistics Unit, Centre for Evaluation of Medicine, 25 Main Street W. Suite 2000, Hamilton, ON, L8P 1H1, Canada. thabanl@mcmaster.ca.
Lehana
L
Thabane
Department of Clinical Epidemiology and Biostatistics, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Population Genomics Program, Chanchlani Research Centre, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.|Department of Psychiatry and Behavioural Neurosciences, McMaster University, 1280 Main St. West, Hamilton, ON, L8S 4L8, Canada. samaanz@mcmaster.ca.
Zainab
Z
Samaan
D015992:Body Mass Index; D002985:Clinical Protocols; D006801:Humans; D009765:Obesity / Q000150:complications* / Q000523:psychology; D012107:Research Design; D059020:Suicidal Ideation; D013405:Suicide / Q000523:psychology; D013406:Suicide, Attempted; D000078202:Systematic Reviews as Topic