Suicidal ideation link to suicide strong in schizophrenia spectrum disorders

By Laura Cowen, medwireNews Reporter

The association between suicidal ideation and later suicide is much stronger in patients with schizophrenia spectrum psychosis than in those with mood disorders, show results of a systematic meta-analysis.

However, the researchers caution that their findings should be interpreted with care because studies with stronger research methods reported weaker associations than those with less strong methods.

Matthew Large (Prince of Wales Hospital, Randwick, New South Wales, Australia) and colleagues reviewed the strength of the association between suicidal ideation and later suicide using data from 14 studies of patients with schizophrenia spectrum psychosis, including 567 suicides, and 11 studies of patients with mood disorders, including 860 suicides.

They found that suicidal ideation was strongly associated with suicide among patients with schizophrenia spectrum psychosis, defined as schizophrenia, schizophreniform disorder or delusional disorder, at a statistically significant odds ratio (OR) of 6.49.

By contrast, the association between suicidal ideation and suicide among patients with mood disorders, defined as major depression, dysthymia or bipolar disorder, was weak and nonsignificant, at an OR of 1.49.

The researchers note that there was high heterogeneity across the studies, but this was partly explained by diagnostic group, “indicating that suicidal ideation is significantly more strongly associated with suicide in patients with schizophrenia spectrum psychosis than among patients with mood disorders.”

Writing in Acta Psychiatrica Scandinavica, Large et al add that this finding is consistent with their hypothesis that “the modest overall association between suicidal ideation and suicide in previous research might have obscured clinically meaningful variation in the extent of this association according to diagnosis.”

The strength of reporting also contributed to study heterogeneity, whereby a weaker association between suicidal ideation and later suicide was observed in studies with stronger methods (strength of reporting score ?5 on a 12-point scale).

Further meta-regression analyses indicated that suicidal ideation was weakly but significantly associated with suicide in studies of patients with mood disorders with follow-up periods of less than 10 years, at an OR of 1.87.

This might be because “[m]ood disorders can be time limited and commonly fluctuate, whereas schizophrenia spectrum disorders are frequently chronic disorders”, the researchers suggest.

Large and co-authors conclude: “Prospective cohort studies of patients drawn from the same population, with standardised methods for eliciting suicidal ideation applied equally to patients with different diagnoses could help define the utility of suicidal ideation as a marker for suicide risk in patients with different psychiatric conditions.”

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