Case-control study of the relationship of depressive symptoms to suicide in a community-based sample of individuals with schizophrenia in China.

backgroundSuicide is the leading cause of premature death among people with schizophrenia. Most studies on suicide and schizophrenia report an associated depression history, but they are based on clinical samples from mostly western countries.

methodsWe conducted a secondary analysis of 74 suicides (cases) and 24 accidental deaths (controls) among persons with schizophrenia identified in a national psychological autopsy study in mainland China using the Chinese version of the Structured Clinical Interview for DSM-IV. A 'depression symptom severity score' based on number, severity, and persistence of depressive symptoms 2 weeks before death was derived from psychiatric interviews with 2 informants; determination of a 'dysfunction due to depressive symptoms score' was based on informants' reports about effects of depressive symptoms on decedents' functioning in the month before death. In addition, the mean number of negative life events was determined along with the effect of the events on the decedent. Comparison of the measures made for cases and controls were made by univariate analysis followed by adjustments using the False Discovery Rate.

resultsCompared to persons with schizophrenia who died by accident, those who died by suicide were more likely to have a recent DSM IV diagnosis of major depression, the symptom of depressed mood, thoughts of death and a prior suicide attempt. In addition, those who died by suicide were more likely to have a higher overall depression severity score and greater dysfunction due to depressive symptoms. DISCUSSION: This community-based study of individuals with DSM-IV schizophrenia who died by suicide in a non-western culture extends findings from clinical studies in western cultures providing data on the importance of depressive symptoms as risk factors for suicide in schizophrenia in a low income rural setting. These findings underline the importance of routine screening for depressive symptoms among patients with schizophrenia.