Relationship of the High Proportion of Suicidal Acts Involving Ingestion of Pesticides to the Low Male-to-Female Ratio of Suicide Rates in China

Background: The reasons for the low male-to-female ratio of suicide deaths in China remain unknown.   Methods: A prospective registry of suicide attempts treated in all 14 general hospitals in a rural county in China was integrated with population and mortality data from 2009 to 2014. Outcomes: There were 160 suicides and 1010 medically-treated suicidal attempts in the county; 84% of female suicides and 58% of male suicides ingested pesticides while 73% of female attempted suicides and 72% of male attempted suicides ingested pesticides. The suicide rate (per 100,000 person-years of exposure) was 8·4 in females and 9·1 in males (M:F ratio=1·08:1) while the incidence of 'serious suicidal acts' (i.e., those that result in death or receive treatment in a hospital) was 81·5 in females and 47·7 in males (M:F ratio=0·59:1). The case fatality of serious suicidal acts was higher in males than in females (19% vs. 10%), increased with age, was highest for violent methods (92%), intermediate for pesticide ingestion (13%), and lowest for other methods (5%). Interpretation: The low male-to-female ratio of suicide rates in rural China is primarily due to the large proportion of suicidal acts in women involving pesticide ingestion -- which have a higher case fatality than the methods used by women elsewhere. As China and other low- and middle-income countries urbanize it is likely that changes in suicide methods will result in more rapid decreases in female than male suicide rates and corresponding increases in the male-to-female ratio of suicide rates. Funding Statement: The study was funded by a grant from the American Foundation for Suicide Prevention. Dr. Tong was supported in part by a United States Public Health Services grant (PHS No. 5D43TW009101, E.D. Caine, PI), and the Beijing Municipal High Rank Health Researcher Training Program (No. 2015-3-111). Dr. Phillips was supported in part by the National Natural Science Foundation of China (NSFC, No. 81371502 and 81761128031). The funding institutions had no role in the design, conduct, analysis, or write-up of the report. Declaration of Interest: The authors have no financial of other conflicts of interest related to this manuscript. Ethics Approval Statement: The authors state: "that all procedures contributing to this work comply with the ethical standards of the relevant national and institutional committees on human experimentation and with the Helsinki Declaration of 1975, as revised in 2008. "