In this study, we used consecutive sampling to enroll suicide victims in 16 randomly selected counties in three provinces in China. Because there is no comprehensive vital reporting system in China, we relied mainly on village doctors and local CDC health professionals to identify eligible cases. To minimize false classifications or missed suicide cases, we trained village doctors in reliable determinations of manner of death and, where the case was ambiguous, arrived at consensus based on consideration of additional information from multiple resources, including village heads and village treasurers. Using these techniques, we identified 392 suicide victims over the 2.5-year study period.
Although suicide rates for women have been reported to be higher than those for men in rural China (3
), a more recent estimate showed that the rural male-to-female ratio for suicide increased from 0.77 in 1991 to 0.94 in 2000 (2
). Our study indicated that the suicide rate for men was slightly higher than that for women in this population. With the continuing improvement in quality of life in rural areas and increased opportunities for rural young women, including easier rural-urban migration in China, the male-to-female ratio for suicide may become closer to that in the West, although it would still be much lower.
The epidemiological assumption is that comparison subjects are representative of the general population in terms of probability of exposure (22
). To optimize validity, we did not use accidental deaths for our comparison group because they might be biased in certain ways (e.g., a higher likelihood of substance misuse or impulsive, risk-taking behavior). The fact that proxy informants for comparison subjects were not affected by bereavement must, however, be taken into consideration in interpreting the results.
There was no significant difference in age or gender distributions between the comparison group and 2005 Chinese national census data, supporting the representativeness of comparison subjects in our study. Our results on the prevalences of mood disorders and psychotic disorders in our comparison group were comparable to those of previous studies in China, while the prevalences of alcohol use disorders and anxiety disorders were lower. For example, in a survey of 5,201 adults in Beijing and Shanghai, the authors reported a 1-year prevalence of 2.2% for mood disorders, 2.7% for any anxiety disorders, and 1.6% for alcohol abuse and dependence (23
). In a large study (N=24,992), Hao and colleagues (24
) reported a prevalence of current alcohol dependence of 3.8% in China. Our primary explanations for the lower prevalence of alcohol use disorders and anxiety disorders in our comparison group are the lower prevalence of alcohol use disorders in the younger population in China (25
) and the limitations of the psychological autopsy method in detecting these disorders (27
The prevalence of mental illness among our suicide victims was 48.0%, lower than previously reported prevalences of suicides among all age groups in China (10
) but similar to the prevalence (44.7%) reported in a recent study of suicide victims in the 15- to 24-year-old age group (28
). We compared our results to those of a systematic review of psychiatric diagnoses in suicide victims under 30 years of age (29
), a meta-analysis that reviewed 13 reports, most from the West. The prevalence of all psychiatric diagnoses is not comparable with our data because we did not include personality disorders or disruptive behavior disorders, which were highly prevalent in younger suicide victims in the West. Compared to the meta-analysis, our results indicated a moderately lower rate of mood disorders (34.9% compared with 42.1%), a substantially lower rate of substance-related disorders (6.4% compared with 40.8%), and a slightly higher rate of psychotic disorders (11.2% compared with 7.2%). Studies in China have shown that substance-related disorders are less common than in the West (30
) and that Chinese young people have a lower risk of alcohol use disorders (25
) and are less likely to engage in heavy drinking (31
). Thus, this lower prevalence of substance use disorders among suicide victims probably does not reflect different relationships between substance use and suicide in the East and West.
Because the prevalence of mental disorders in both suicide victims and comparison subjects in our study was lower than rates reported for samples from the West, we also compared odds ratios for mental disorders among suicide victims. A systematic review that included 24 psychological autopsy case-control studies reported a crude odds ratio of 5.24 for substance-related disorders and 13.42 for mood disorders (33
). These ratios are similar to or lower than those in our study, which suggests that the lower prevalence of mental illness we observed in young Chinese rural suicide victims may be due to the difference in prevalence of mental illness in the general population in China.
The prevalence of mental illness was significantly higher in male than in females suicide victims, and the difference remained significant after controlling for other characteristics. This result is consistent with that of a study on suicide victims 15–24 years of age in China (28
). No alcohol- or substance-related disorders were diagnosed in female suicide victims, which is consistent with the previously reported low prevalence of alcohol use disorder (0.2%) among women in China (24
). After stratification by gender, the odds ratio for having a mental disorder diagnosis was substantially higher among males than among females. This finding suggests that specific suicide prevention and intervention programs targeting Chinese rural females other than identification and treatment of mental illness are needed.
Consistent with previous reports (10
), we found that stressful life events and lower levels of social support were important risk factors. Our findings indicate that besides mental illness as a major risk factor for suicide among young people in rural China, other psychological, social, and cultural factors must play important roles, particularly in women. Future studies should explore the effects of constructs such as social integration (34
), cultural values and norms such as face and impulsivity (35
), and psychological strain (36
) on Chinese suicide.
The lower prevalence of mental illness among Chinese suicide victims provides a unique opportunity to explore possible interactions between mental disorders and other risk factors in suicide. Additive interactions were found between mental illness and lower levels of social support, but not with recent or long-term life events. Mental illness may increase an individual’s vulnerability through damage to the ability to maintain existing social relationships, to develop new relationships, or to utilize social support.
One of the limitations of this study was size of the living comparison sample. The total number of living comparison subjects was too small for a detailed examination of the association between suicide and certain categories of mental disorders. For instance, only two comparison subjects were diagnosed as having schizophrenia. This is probably also a major challenge in other psychological autopsy studies of suicide. In a recent similar study in Pakistan, only six of 100 living comparison subjects were diagnosed as having mental illness (38
). Our suggestion for future studies would be to enroll multiple living comparison subjects for each suicide victim (e.g., using a 1:2 or 1:3 case-control design) to increase the number of comparison subjects with mental disorders.
Second, there are several methodological concerns in a case-control psychological autopsy study. The use of proxy informants, the retrospective data collection, the lack of blinding regarding case and comparison subjects, and the potential impact of bereavement and stigma against suicide and mental illness on reporting may have an impact on the reliability of the data. Also, our strategy of scheduling interviews with proxy informants for suicide victims 2 to 6 months after suicide clearly differed from our strategy with informants for living comparison subjects and could increase the risk of recall bias.
Third, because different groups of interviewers and psychiatrists had been working on data collection and diagnoses of mental disorder separately at various research sites for more than 2 years, the reliability of diagnoses across investigators, time, and location was a major challenge. However, the diagnoses made in this study are very likely reliable because of the efforts we put into training for all interviewers and psychiatrists, the excellent interrater reliability of diagnoses, and the fact that the prevalence of mental illness among suicide victims and comparison subjects did not differ significantly across research sites and across time.