Association between body mass index and suicide, and suicide attempt among British adults: the health improvement network database.

Abstract

To examine the associations between body mass index (BMI) and incidence rate (IR) of suicide attempt and suicide. 849,434 British adults were identified from The Health Improvement Network (THIN) database between January 2000 and October 2007. BMI was categorized into six levels: <18.5 (underweight), 18.5-24.9 (normal weight), 25.0-29.9 (overweight), 30.0-34.9, 35.0-39.9, and ≥40 (obese levels I-III). We identified 3,111 suicide attempts by Read codes and 75 suicides with medical records. The overall IR of suicide attempt was 82.2 cases per 100,000 person-years. The IR decreased with BMI in men with depression (471.3-166.0 cases per 100,000 person-years, P for trend = 0.02) and in men without depression (241.5-58.0 cases per 100,000 person-years, P for trend < 0.0001). In women with depression, an L-shaped relationship was observed, that is, a higher rate in underweight group when compared with reference group (503.2 vs. 282.7 per 100,000 person-years) and no significant differences in others (231.8-195.5 cases per 100,000 person-years). In women without depression, the IR was U-shaped with BMI (125.2 in underweight, 68.6 in reference, and 48.5-79.9 cases in overweight and obese I-III groups per 100,000 person-years, P for trend < 0.0001). The above trends remained after adjustment for the covariates. Regarding suicide, the overall IR was 2.0 cases per 100,000 person-years, which tended to decrease with BMI (P = 0.14). We concluded an inverse linear association between BMI and suicide attempt among men, an L-shaped association in nondepressive women, and a U-shaped association in depressive women were observed. The study also suggested an inverse linear tendency between BMI and suicide.