Association between irritability and suicide-related outcomes across the life-course. Systematic review of both community and clinical studies

Abstract

Background: Irritability is gaining considerable attention as a risk factor for suicide-related outcomes (suicide mortality, attempt, and ideation). However, the evidence of this association is scant. We conducted a systematic review of the evidence regarding the associations between irritability and suicide-related outcomes across the life-course.

Methods: We conducted a systematic search on Medline and PsycINFO (up to January 2018) for original articles published in English investigating the association between irritability and suicide-related outcomes. Two researchers independently screened the articles, assessed the quality of the evidence (New-Castle-Ottawa Scale) and extracted study characteristics.

Results: Thirty-nine studies were retrieved, most were of low/medium quality. Twelve assessed irritability in childhood/adolescence (6 in community samples, 6 in clinical samples) and 27 in adulthood (7 in community samples, 20 in clinical samples). In both childhood/adolescence and adult samples, most community-based studies reported a positive association between irritability and suicidal ideation and/or attempt, while clinical studies reported mixed findings. More specifically, in clinical studies, the association of irritability with suicide-related outcomes (i) was not supported among adult depressed patients, (ii) findings were inconsistent in adult bipolar patients, (iii) for inpatients/outpatients with various psychiatric disorders/conditions, association was observed in adulthood but not in childhood/adolescence.

Limitations: Differences in methodology and definition/measurement of irritability limited the comparability of included studies.

Conclusions: Although irritability has been proposed as a promising transdiagnostic factor associated with suicide-related outcomes, the absence of consensus in the definition of irritability (vs anger or reactive/impulsive aggression), the poor methodological quality, and the lack of developmental considerations mitigate the conclusions.

Keywords: Irritability; Review; Suicidal ideation; Suicide; Suicide attempt.