Relationship of the high proportion of suicidal acts involving ingestion of pesticides to the low male-to-female ratio of suicide rates in China

AIMS: The 2014 World Health Organization report on global suicide identified large differences in the male-to-female ratio of suicide rates between countries: most high-income countries (HICs) report ratios of 3:1 or higher while many low- and middle-income countries (LMICs) – including China and India – report ratios of less than 1.5:1. Most authors suggest that gender-based social-cultural factors lead to higher rates of suicidal behaviour among women in LMICs and, thus, to relatively high female suicide rates. We aim to test an alternative hypothesis: differences in the method and case-fatality of suicidal behaviour – not differences in the rates of suicidal behaviour – are the main determinants of higher female suicide rates in LMICs. METHODS: A prospective registry of suicide attempts treated in all 14 general hospitals in a rural county in China was established and data from the registry were integrated with population and mortality data from the same county from 2009 to 2014. RESULTS: 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 received 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 v. 10%), increased with age, was highest for violent methods (92%), intermediate for pesticide ingestion (13%) and lowest for other methods (5%). CONCLUSIONS: The incidence of medically serious suicidal behaviour among females in rural China was similar to that reported in HICs, but the case-fatality was much higher, primarily because most suicidal acts involved the ingestion of pesticides, which had a higher case-fatality than methods commonly used by women in HICs. These findings do not support sociological explanations for the relatively high female suicide rate in China but, rather, suggest that gender-specific method choice and the case-fatality of different methods are more important determinants of the demographic profile of suicide rates. Further research that involves ongoing monitoring of the changing incidence, demographic profile and case-fatality of different suicidal methods in urban and rural parts of both LMICs and HICs is needed to confirm this hypothesis.