In recent years, much attention has been given to suicide prevention in China. Since 1999, suicide prevention has been listed as a mental health priority of the Ministry of Health in China [33
]. We systematically reviewed a range of risk factors of suicidal behaviors in China. Given that there is a large body of literature on the associations between numerous factors and suicidal behaviors, our meta-analysis only provides a review of the strongest and most consistently reported factors.
In Western countries, males have a higher risk of completed suicide than females [52
]. In China, based on the studies included in our meta-analysis, the opposite pattern was identified; females had a 2.35-fold higher risk of completed suicide than males. In the subgroup analysis, when we excluded the study [7
] with data covering 2005–2008, the pooled results of studies with pre-2000 data indicated that women had an even higher risk (3.03-fold) of suicide, which hinted that the impact of gender on suicide in China is gradually decreasing. This result is consistent with that of [Zhang et al. 5
], who found that the female suicide rate decreased more than the male suicide rate during the period between 1987 and −2008 (20.4 to 6.2/100,000 vs. 14.9 to 7.0/100,000, respectively) [5
],which is due to the economic development over the past decades resulting in increase of female social status in China, particularly in rural areas [5
]. Our meta-analysis indicated that people living in rural areas and those with less education have a higher risk of completed suicide (pooled OR
2.86 and 2.33, respectively). These results may explain the high suicide rates in rural areas of China [5
Socio-family environmental factors, such as personal relationships, family violence, social and family conflicts and a sense of isolation, were significantly associated with a higher risk of completed suicide [52
]. Previous reviews also report that multiple social and interpersonal factors, such as parent/family and peer relationships, are important for our understanding of adolescent suicidality [57
]. The present meta-analysis also indicated that being in a special family (single or remarried parent), poor academic achievement and study pressure increase the risk of developing suicide ideation among adolescents and college students (pooled OR
1.50, 1.25 and 1.27, respectively). These factors may influence the development of personality or psychological disorders among youth and adolescents [58
]. Our results highlight the importance of establishing harmonious family and social environments for suicide prevention. School factors should also be considered for student suicide prevention.
As for the psychiatric/psychological factors, it has been reported that mental disorders, mood disorders (severe depression, anxiety, sadness, and so on), and personality disorders are major risk factors for suicidality worldwide, particularly in Western countries [52
]. However, Zhang et al. pointed out that in China, although still important, psychiatric factors are not the main factors associated with suicide [5
]. Our meta-analysis similarly found that people with a mood disorder had 2.48-, 3.44- and 20.31-fold higher risk of suicide ideation, suicide attempt and completed suicide in China, respectively. However, the included studies qualitatively described psychiatric/psychological factors using with/without sadness, depression, and despair, rather than quantitatively measured it with a standard instruments, which may result in different criteria implemented in different studies to decide with or without these mood disorders. Therefore, a standard scale in the future studies is needed for measuring mood disorders in order to compare between studies.
Negative/stressful life events influence health in many respects. Previous studies have reported that stressful life events are associated with suicide. For example, poor physical health, disabilities, history of suicide attempts, life events, and suicide of others are significant suicide risk factors [54
]. An earlier study also reported that the presence of legal/disciplinary problems, potentially fatal illnesses, persistent stress, previous self-harm, and family history of suicide are risk factors for suicidal behaviors [52
]. Our meta-analysis indicated that people who had experienced a negative/stressful life event or a recent change in life, and those who had previously attempted suicide or had relatives/friends who had committed suicide had a higher risk of completed suicide. We also found that poor physical health and exposure to the suicide of a family member were risk factors for suicide ideation and suicide attempt. Indeed, a negative life event can trigger suicide or suicidal behavior because negative life events are associated with psychological disorders [66
Earlier studies have identified alcohol, smoking and drug disorders as being suicide risk factors [37
]. Misuse of alcohol or drugs was also a risk factor for suicide ideation and suicide attempt [55
]. Our meta-analysis similarly found that among youth, smoking, alcohol use, and drug use were risk factors for suicide ideation (pooled OR
= 1.67, 1.96 and 1.97, respectively), and smoking and alcohol use were risk factors for suicide attempt (pooled OR
2.03 and 2.50, respectively). It has long been recognized that substance abuse (alcohol and drug use) is frequently correlated with psychiatric disorders [71
], and that smoking in youth is associated with psychiatric disorders (depression and anxiety) [73
], which may explain how these unhealthy lifestyle behaviors increased the risk of suicidal behaviors.
Our meta-analysis also indicated that being an only child, pesticides being stored at home, a poor economy, lower social support, and seeking psychological help in hospitals were risk factors for suicide in China. However, further study is needed to confirm these risk factors because there were only a few studies of these factors included in our meta-analysis, all with small sample sizes.
This review provides a relatively comprehensive picture of risk factors for suicidality in China. However, our meta-analysis has some limitations. First, biases have been introduced because non-published data, papers without full text and papers published in languages other than English or Chinese were not included. Second, there was a lack of uniform measurement of complex socio-psycho-behavioral factors among the included studies, and they covered widely different population groups, producing heterogeneity between the studies even with a subgroup analysis. Third, it is possible that the studies included in this review underestimated the association between the risk factors and suicide behaviors. Participants of studies on sensitive topics such as suicide often underreport behavior to avoid embarrassment or possible stigma [75
]. Fourth, the vast majority of the included studies were cross-sectional and did not allow for inferences on cause-effect mechanisms.
Our study identified four implications for the future. First, to draw comparisons between studies of different populations and regions, it is important to emphasize the use of standardized measures of socio-psychological factors and to place adequate focus on very specific population groups in any future studies. Second, risk assessment is more necessary to identify modifiable or treatable high-risk factors and available protective factors in order to take effective countermeasures Third, most of the present studies were cross-sectional studies, therefore the future researches designed with case–control or cohort studies are needed in order to make reliable inferences on cause-effect mechanisms. Fourth, there is an urgent need to emphasize further study of interventions to prevent suicide. Intervention programs in China that simultaneously address multiple factors associated with suicide would be most appropriate since suicide is multi-factorial health problem [76