Meta-analysis of clinical risk factors for suicide among people presenting to emergency departments and general hospitals with suicidal thoughts and behaviours

Background: Suicidal thoughts and behaviours (STB) are a common reason for presentation to emergency departments and general hospitals. A meta-analysis of the strength of clinical risk factors for subsequent suicide might aid understanding of suicidal behaviour and help suicide prevention. Methods: We conducted a meta-analysis of cohort and controlled studies on clinical risk factors and later suicide among people presenting to emergency departments and general hospitals with STB. Data were extracted from papers meeting inclusion criteria, published in Medline, PsycINFO, and Embase between 1 January 1960 and 10 October 2022 using papers located with the search terms ((suicide*).m_titl AND (emergency* OR accident and emergency OR casualty OR general hospital OR toxicology service).mp) or were indexed in PubMed and had titles located with the search terms (suicide* OR self-harm OR self-harm OR self-injury OR self-injury OR self-poisoning OR self-poisoning OR overdose OR para-suicide OR parasuicide [title/abstract]) AND (Emergency department OR emergency room OR Casualty OR general hospital OR toxicology OR accident and emergency [all fields]). Data about the association between clinical risk factors and suicide extracted from three or more studies were included in a random-effects meta-analysis of the odds of later death by suicide. The study was registered in PROSPERO and conducted according to MOOSE and PRISMA guidelines. Results: Seventy-five studies reported on 741,624 people, of which 19,649 died by suicide (2.65%). Male sex (odds ratio (OR) = 1.99) and age (OR = 2.01) were the most consistently reported risk factors. The strongest associations with subsequent death by suicide related to violent self-harm methods at the hospital presentation, including: unspecified violent method (OR = 4.97), any violent method (OR = 4.57) and the specific violent methods of drowning (OR = 4.32), hanging (OR = 4.26), and use of firearms (OR = 10.08). Patients categorised as higher risk using suicide prediction scales or any other method that combined risk factors had moderately increased odds of suicide (OR = 2.58). Younger age, Black and Hispanic ethnicity, overdose, a diagnosis of adjustment disorder, and the absence of any psychiatric diagnosis were protective against suicide. Conclusions: Most risk factors for suicide among people who have presented with STB are not strongly associated with later suicide. The strongest risk factors relate to self-harm methods. In the absence of clear indicators of future suicide, all people presenting with suicidality warrant a thorough assessment of their needs, and further research is needed before we can meaningfully categorise people with STB according to suicide risk.