Background

US suicide rates have increased by 30% since 2000, highlighting the need to develop more effective suicide prevention strategies, including identifying novel risk factors. Obesity is associated with multiple medical and mental health co-morbidities. Prior studies assessing the correlation between BMI and risk of suicide death have yielded mixed results, with some showing an inverse relationship, while others failed to show an association or demonstrated a positive correlation. To our knowledge, no studies have looked at the association between suicide death and obesity diagnosis. This study aims to clarify the association between death by suicide and obesity, by looking at the associations between both suicide death and BMI, as well as suicide death and presence of obesity diagnosis in the EHR.

Methods

A case-control study was conducted to investigate the association between risk of suicide death with both BMI and obesity diagnosis (ICD-9:278). This study involved data from the EHRs of 7 Mental Health Research Network affiliated healthcare systems and included a total of 1098 individuals who died by suicide and 5490 controls matched by time period and site.

Results

After adjusting for various covariates, obese individuals, defined by BMI≥ 30.0, had a lower risk of suicide death (OR=0.60,95%CI=0.5-0.72,p<0.0001). Compared with a normal range BMI of 18.5-24.9, adjusted odds ratios for suicide mortality were 0.80 (95%CI=0.66-0.97,p=0.023), 0.66 (0.52-0.84,p= 0.0006), 0.35 (0.24-0.52,p<0.0001), and 0.36 (0.23-0.57,p<0.0001) for BMI values of 25.0-29.9, 30.0-34.9, 35.0-39.9, and ≥ 40.0 respectively. Obesity diagnosis was also associated with a lower risk of suicide death (OR=0.44,95%CI= 0.33-0.59,p<0.0001).

Conclusions

Obesity, defined by both BMI and presence of obesity diagnosis in the EHR, is associated with a lower risk of suicide death. Further research investigating this relationship could provide new insights into methods of suicide prevention.