| BackgroundEvery year approximately 1,000,000 people commit suicide. In China, a total of 287,000 die by suicide per year, accounting for 29% of all deaths in the world. Suicide is the fifth most important cause of death in China, and the first cause of death among 15 to 34 age population. Suicide, particularly youth suicide in rural areas, is a major public health issue and social problem with which our country is currently confronted.Compared to Western countries, there are three unique characteristics of Chinese suicide:1) the male/female suicide ratio was 0.95 in 2000 while in most countries in the world male suicide rates are three-fold to five-fold higher than the female rates; 2) rural suicide rates are two-fold to three-fold greater than the urban suicide rates; 3) there are two peaks in the curve of suicide rate among different ages, 15-34 age group and over 60 age group. The rural/urban suicide ratio is 4 to 5 among population older than 60.Suicide research in China now mainly concerns on risk factors and protective factors for suicide ideation and attempted suicide, but effective suicide prevention and intervention still need deeply explore the characteristics and influential factors of completed suicide. The development and application of Psychological Autopsy offers an effective way to solve difficulties in research of influential factors for completed suicide. Through interviews with "people who know the information of the suicide", Psychological Autopsy is able to effectively reconstruct psychological, social, and environmental factors related to the suicide, and better understand suicide causes and related social environment, therefore it is the most scientific and operational approach for completed suicide research.As to now, through Psychological Autopsy, we have known the following influential factors for completed suicide:mental disorders, negative life events, impulsivity, social support, physical diseases, socio-economic status, interpersonal conflicts, suicide attempt history, family suicide history, cultural factors, and accessibility to lethal methods for suicide.However, Psychological Autopsy is still a relatively new concept in the field of suicide research in our country. There are limited Psychological Autopsy studies carried out in Chinese mainland, while the Psychological Autopsy studies specific to rural youth suicides are even less. Especially for the gender differences in suicide mortality issue, there is little research on the deep comparison of the characteristics of male and female suicides in the international, however, in China there is almost no literature in this field. The study of rural youth suicide plays an important part in guiding suicide prevention work in China. We chose two informants for each target person in case and control groups to conduct Psychological Autopsy, fully and deeply compared the characteristics of suicidal behavior and the risk factors for suicide between male and female suicides. Also, we identified gender-specific cluster characteristics of young suicide decedents in rural areas, with a view of providing a scientific basis for more targeted and effective suicide prevention and intervention in our country.Objectives1. To compare the gender-specific characteristics of suicidal behavior of completed suicides in rural young people.2. To explore risk factors associated with socio-demographic variables, psychological traits, psychosocial stress, and mental disorders for completed suicide in rural young men and women respectively, as well as to compare the gender differences in the exposure rates, scores, and risk degrees of the risk factors with the goal of explaining the gender differences in the mortality of Chinese rural suicides.3. To explore the similarities and differences of the risk factors for completed suicide between rural young men and women, and to identify gender-specific cluster characteristics of high-risk suicide, with a view of providing scientific bases for suicide prevention and intervention in rural communities. Methods1. Subjects and MethodWe randomly selected 16 counties or county-level cities in Liaoning, Hunan, and Shandong provinces, then consecutively sampled rural residents aged 15-34 years who died by suicide during the period from 1st October,2005 to 30th June,2008 in those 16 counties or cities, meanwhile randomly sampled rural living residents at the same age range as controls of those suicides. The list of suicides originated from the cause of death surveillance systems of Centers for Disease Control and Prevention at the county levels. Totally 392 suicides and 416 controls were included in this study.We used case-control psychological autopsy method. All data were selected by face-to-face interviews.2. InstrumentsGeneral information included:personal information including age, gender, educational status, marital status, living arrangement, personal income, status in family, religious belief, health condition; family circumstances including family economic status, family relationships, family suicide history, and pesticides stored at household.Suicidal behavior characteristics of completed suicide investigation included: suicide time, suicide site, suicide method, etc. Beck Suicide Intent Scale was used to measure the intensity of death intent among the suicides.Psychological traits:Beck Hopelessness Scale (BHS), Hamilton Rating Scale for Depression (HAM-D), Center for Epidemiologic Studies Depression Scale (CES-D), State-Trait Anxiety Inventory (STAI), Dickman Impulsivity Inventory (DII), and Coping Response Inventory (CRI).Psychosocial stresses were examined by the Paykel Life Events Scale (IRLE) and the Duke Social Support Index (DSSI).Mental disorders:the Structured Clinical Interview for DSM-IV Axis I Disorders Research Version (SCID-I) was applied. Axis I diagnoses of mental disorders were given by psychiatrists. 3. Statistical AnalysisSPSS 16.0 was used for data analysis. For numerical variables, such as age, income, scores of psychological scales, stimulation amounts of negtive life events etc., t test or Mann-Whitney U test was applied according to the distribution types of data. For categorical variables, such as the distribution, exposure rates, incidence rates of suicide-related factors etc., Chi-Square test, Fisher's exact test or Monte Carlo simulation method was used to estimate the probabilities.The reliability of scale was examined by Cronbach's a coefficient, meanwhile, the consistency between two informants was evaluated by the Intraclass Correlation Coefficient or Kappa consistency test. Rayleigh test was used for testing whether the central tendency existed in suicide date and suicide time. Hierarchical Linear and Nonlinear Modeling (HLM) was applied to explore the gender differences in the risk degrees of the influential factors for completed suicide in rural areas. Multivariate Logistic regression models were established to discuss risk factors for suicide among rural young men and women, respectively. The Classification Tree analysis was used to explore the gender-specific cluster characteristics of rural youth at high risk of suicide.Main Results1. Informants'basic information:In all types of informants, the first informants of the completed suicides were the oldest, and had lowest education level, highest proportion of separated, divorced or widowed, and lowest family annual income. In addition, the CES-D scores of the relatives and friends of the suicides were much higher than those of the controls, especially, the first informants of the completed suicides had the highest degree of depression (CES-D mean score=20.57).2. The gender-specific characteristics of suicidal behavior for completed suicides among rural young people. The peak suicide periods for male suicides were in May, June and mid-July, while for female suicides were in late-June, July, August and late-September. The peak suicide times for male suicides focused on 11:20 a.m. to 4 p.m., while for female suicides were clustered at about 11:00 a.m. to 2:00 p.m. Gender comparisons of suicide sites, methods of suicide, and suicide ideations showed that female suicides were more likely to commit suicide indoor (P=0.002), using a moderate method "ingestion of poison" for suicide (P=0.007), and having significantly lower preparation of pre-suicidal behavior than that of male suicides (P=0.038).3. Comparison results of the exposure rates, scores, and risk degrees of the risk factors for completed suicide between rural young men and women.1) Basic information:comparing to female suicides, male suicides had significantly less proportion of married (P<0.001) and higher personal income (P=0.001), but the proportion of female. suicides who believed in afterlife was significantly higher (P=0.007). Gender differences in family conditions showed that male suicides had significantly less family annual income (P=0.023) and worse relationships with spouse and parents (P<0.001;P=0.025). However, the exposure rates of most socio-demographic variables had no significant gender differences, and the OR values of these factors were similar between rural young men and women.2) Psychological traits:male suicides had relatively higher level of hopelessness, depression and trait anxiety (P values were 0.002,0.018,0.001, respectively). There was no significant gender differences in the total scores of impulsivity and coping skills, but as for the negtive coping skills, the mean socre of "acception or abandonment" subscale was significantly higher in male suicides (P=0.046), while the mean score of "emotions release" subscale of female suicides was significantly higher (P=0.013). The gender comparison of OR values of the psychological factors found that coping abilities of "problem solving" and "seeking compensation" significantly reduced suicide risks among rural young women (male/female OR ratios were 1.04 and 1.03, respectively; P values were 0.032 and 0.019, respectively), however, two kinds of negative coping styles "cognitive evading" and "emotions release" significantly increased suicide risks among rural young men (male/female OR ratios were 1.03 and 1.06, respectively; P values were 0.038 and 0.002, respectively). With regards to the OR values of other suicide risk factors in this respect, there was no significant gender difference.3) Psychosocial stresses:there was an average of 3.6 negative life events occurred in male suicides, and the number was significantly higher than that occurred in female suicides (P=0.033), which was an average of 3.1 negative life events. Male suicides had more possibilities to expose to negative life events. The incidence rates of six events were significantly higher among male suicides, there were "extremely family economic difficulties,""loss of face, suffered discrimination or being misunderstood by others,""decline in revenue," "laid-off or unemployed (more than a month)," "once be in prison or be arrested," and "be involved in legal disputes."(P values were <0.001,0.001,0.001,0.013,0.018,0.034, respectively). Moreover, the total stimulation amounts of family life events, work and study events, and law or other related events were significantly higher in male suicides (P values were 0.008, <0.001, 0.014, respectively). However, the incidence rate of "educating children difficulties" and the acute stimulation amount of family life events were significantly higher in female suicides (P values were 0.014 and 0.050, respectively). Besides, female suicides had higher social support than male suicides (P=0.014). The impacts of negative life events, perceived social support and instrumental support on suicide were similar between rural young men and women, but social interaction support significantly reduced the suicide risks in rural young women (male/female OR ratios=1.06, P=0.012).4) Mental disorders:55.1% of male suicides and 39.3% of the female suicides had at least one diagnosis of mental illness. The total prevalence of mental disorders, as well as of major depression, dysthymic disorder, and alcohol use disorder were significantly higher in male suicides (P values were 0.002,0.021,0.025, <0.001, respectively). The suicides with mental disorders had significantly higher levels of hopelessness, depression, and trait anxiety than those in the suicides without mental disorders. Furthermore, the suicides with mental disorders had relatively lower positive coping skills. Among young female suicides, the score of non-functional impulsivity of those without any mental disorder was significantly higher than those with mental disorders (P=0.047). However, there was no such difference in young male suicides.4. Multivariate analysis results of risk factors for suicide among rural young people. For rural young men, higher education level, married status, high scores of "seeking instruction and support" and "seeking compensation" subscales, reduced risks of suicide, while high scores of "future expectation" and "acception or abandonment" subscales, acute negtive life events, and mental disordors, increased risks of suicide. For rural young women, joining Communist Party or Communist Youth League, and high score of "seeking instruction and support" subscale reduced risks of suicide, while living alone, having a pesticide stored at household, depression, high scores of "feeling about the future" and "acception or abandonment" subscales, acute and chronic negtive life events, increased risks of suicide.Cluster characteristics of rural youth at high risk of suicide mainly were:1) young men, severe despair, with or without mental disorders; 2) young women, severe despair, with or without negative life events; 3) young women, low despair, but have a pesticide stored at household.Conclusions1. Characteristics of suicidal behavior:comparing to rural young male suicides, female suicides were less prepared before suicidal behavior, besides the suicidal behavior of young women with lower hopelessness and without mental disorders in rural areas was related to impulsive personality and the stresses caused by negative life events, showing that more women than men engage in low-intent and impulsive suicidal behavior.2. Risk factors for suicide:comparing to rural young male suicides, female suicides had lower level of hopelessness, depression, trait anxiety, and lower exposure rate of negative life events. The OR values of most risk factors for suicide were basicly no significant gender differences. However, the coping abilities of "problem solving" and "seeking compensation" as well as social interaction support significantly reduced suicide risks among rural young women, while two kinds of negative coping styles "cognitive evading" and "emotions release" significantly increased suicide risks among rural young men. We could not identify the key characteristics which effect on the higher mortality of female suicide.3. Influential factors for suicide among rural young men:high level of education, married stutas, high abilities of "seeking instruction and support" and "seeking compensation" were protective factors for suicide; mental disorder, high hopelessness score of "future expectation", negative life events, and "acception or abandonment" coping style were risk factors for suicide.4. Influential factors for suicide among rural young women:joining Communist Party or Communist Youth League, and high ability of "seeking instruction and support" were protective factors for suicide; living alone, having a pesticide stored at household, high hopelessness score of "feeling about the future", depression, negative life events, and "acception or abandonment" coping style were risk factors for suicide.Significance and InnovationIt's the first time in the domestic to systematically compare the gender-specific characteristics of suicidal behavior and risk factors for suicide between rural male suicides and female suicides, and explored the gender differences in the mortality of Chinese rural suicides. This study also took the lead on the comparison of differences and similarities of risk factors for suicide between rural young men and women, and the exploration on the gender-specific cluster characteristics of high-risk suicide, therefore provided a useful reference for making more targeted suicide prevention and intervention strategies for our country. Furthermore, during the gender comparison study of risk factors for suicide, two-level nonlinear model was used to explore the gender differences in the risk degrees of the risk factors, comprehensivly evaluating the influential effects of risk factors for suicide on different gender populations.
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