Risk factors for suicide over a lifetime — systematic review

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A review of previous studies into suicide worldwide by Oxford University and the Karolinska Institutet identifies the effects of individual and environmental risk factors, as well as of the effectiveness of assessment and treatment approaches, over the different stages of a lifetime.

The researchers found that among individual risk factors for suicide, depression, bipolar disorder, schizophrenia-spectrum disorders, substance use disorders, epilepsy, and traumatic brain injury each increases the odds of completed suicide by a factor of more than 3 during the course of a lifetime.

The researchers looked at the effectiveness of interventions at a population level to target high-risk groups or individuals, such as restricting access to poisons or firearms, but found that these measures vary in effectiveness by country and culture.

Professor Seena Fazel of Oxford University’s department of psychiatry, said: “This is the first evidence synthesis to look at suicide at a population-wide level and through the course of peoples’ lives, which is particularly useful because many risk factors contribute differentially in childhood, adolescence, and adulthood, and we have attempted to identify both replicated factors and their strength.

“Preventing suicide involves understanding the full picture of contributing factors throughout a lifetime, and there is no simple solution or fix. What we wanted to do in this review was to provide an overview of the latest evidence of how to identify higher risk individuals, and one that could be used in any country.”

The researchers concluded that when assessing and treating suicide risk: a person who presents with suicidal thoughts may be at risk for suicide even if there are few overt symptoms of a psychiatric disorder; suicide risk should be assessed by considering predisposing and precipitating factors; the risk of suicide should be managed through regular follow-up and brief psychological therapy; for persons with symptoms of mental illness, pharmacologic treatment should also be considered; the suicidal person, family members, and those who provide care should all take part in ensuring a safe environment, with removal of the means of suicide such as guns or certain medications; if the risk of suicide is considered to be high or uncertain, the person should be referred immediately to mental health services, and the use of risk-assessment tools should be considered to aid risk stratification and communication among services.

Another study has found that nearly half of deployed soldiers thinking about suicide show no obvious signs that would help mental health professionals identify them. Researchers pored through data on 3,957 soldiers serving in Afghanistan in 2012 and found that 11.7% reported ever having suicidal ideation during their lives, while 3% reported suicidal ideation in the past year and 1.9% reported suicidal ideation in the past 30 days.

The researchers found that 40% of those who said they had contemplated suicide in the past 30 days had not been diagnosed with a major mental health problem and did not show any other signs that would help health providers identify them as being at risk.

“These soldiers wouldn’t have been picked up if they were just screened for mental health disorders,” said co-author Dr Robert Ursano, director of The Centre for the Study of Traumatic Stress at the Uniformed Services University.

As for the other 60% who reported recent suicidal ideation, there were predictors, Ursano said. The biggest was a history of major depressive disorder. Also important was a history of non-combat related trauma, which could include being in a motor vehicle accident, being sexually assaulted, experiencing a tornado or being mugged, Ursano said.

Combat trauma wasn’t predictive, Ursano said. “In the theatre, they’re all being exposed to combat trauma,” he explained. “So, it didn’t distinguish who was at risk.”

To take a closer look at what factors might help health care providers figure out who might be most at risk, Ursano and his colleagues turned to a questionnaire that had been filled out in July 2012 by soldiers deployed to Afghanistan. The researchers focused on a sample of 3,957 who were representative of the 87,032 serving in Afghanistan at the time. The researchers also had information from military administrative records on gender, age, race/ethnicity, education and marital status.
Also in the analysis were lifetime and past-12-month exposures to traumatic and stressful events.

The soldiers were asked about combat-related traumas, such as whether they had taken enemy fire, whether they had been wounded or whether a unit member had been wounded or killed. They were asked about lifetime stressors, including serious physical assault, sexual assault, murder of a close friend or relative, and involvement in disasters.

When the researchers analysed factors that could affect the likelihood a soldier might start thinking about suicide, they found several: Being white raised the risk threefold, experiencing noncombat trauma raised the risk twofold, major depression prior to the past 30 days raised the risk nearly five-fold, and major depression in the past 30 days raised the risk 31-fold.

Among the soldiers who had thought about suicide in the past 30 days, five (6%) attempted suicide in the 18 months after filling out the questionnaire. Among the soldiers who had not experienced suicidal ideation, six (0.14%) attempted suicide. “This is a very important study,” said Nadine Melhem, director for the programme of neurobiology of stress response and suicide at the University of Pittsburgh, who wasn’t involved in the study. “It suggests we can look for predictors before deployment to see if they are at risk of suicidal ideation in order to help them.”

The study shows that suicidal ideation in soldiers is triggered by similar factors to those leading civilians to think about suicide, said Dr Paul Nestadt, an assistant professor in the department of psychiatry and behavioural sciences at the Johns Hopkins School of Medicine in Baltimore, who also wasn’t involved in the research.

What the study can’t say is who is likely to attempt suicide in the next 30 days, Nestadt noted. “That is what I want to know,” he added.

Importance: Understanding suicide ideation (SI) during combat deployment can inform prevention and treatment during and after deployment.
Objective: To examine associations of sociodemographic characteristics, lifetime and past-year stressors, and mental disorders with 30-day SI among a representative sample of US Army soldiers deployed in Afghanistan.
Design, Setting, and Participants: In this survey study, soldiers deployed to Afghanistan completed self-administered questionnaires in July 2012. The sample was weighted to represent all 87 032 soldiers serving in Afghanistan. Prevalence of lifetime, past-year, and 30-day SI and mental disorders was determined. Logistic regression analyses examined risk factors associated with SI. Data analyses for this study were conducted between August 2018 and August 2019.

Main Outcomes and Measures: Suicide ideation, lifetime and 12-month stressors, and mental disorders were assessed with questionnaires. Administrative records identified sociodemographic characteristics and suicide attempts.
Results: A total of 3957 soldiers (3473 [weighted 87.5%] male; 2135 [weighted 52.6%] aged ≤29 years) completed self-administered questionnaires during their deployment in Afghanistan. Lifetime, past-year, and 30-day SI prevalence estimates were 11.7%, 3.0%, and 1.9%, respectively. Among soldiers with SI, 44.2% had major depressive disorder (MDD) and 19.3% had posttraumatic stress disorder in the past 30-day period. A series of analyses of the 23 grouped variables potentially associated with SI resulted in a final model of sex; race/ethnicity; lifetime noncombat trauma; past 12-month relationship problems, legal problems, and death or illness of a friend or family member; and MDD. In this final multivariable model, white race/ethnicity (odds ratio [OR], 3.1 [95% CI, 1.8-5.1]), lifetime noncombat trauma (OR, 2.1 [95% CI, 1.1-4.0]), and MDD (past 30 days: OR, 31.8 [95% CI, 15.0-67.7]; before past 30 days: OR, 4.9 [95% CI, 2.5-9.6]) were associated with SI. Among the 85 soldiers with past 30-day SI, from survey administration through 12 months after returning from deployment, 6% (5 participants) had a documented suicide attempt vs 0.14% (6 participants) of the 3872 soldiers without SI.
Conclusions and Relevance: This study suggests that major depressive disorder and noncombat trauma are important factors in identifying SI risk during combat deployment.

Robert J Ursano; Holly B Herberman Mash; Ronald C Kessler; James A Naifeh; Carol S Fullerton; Pablo A Aliaga; Cara M Stokes; Gary H Wynn; Tsz Hin Hinz Ng; Hieu M Dinh; Oscar I Gonzalez; Alan M Zaslavsky; Nancy A Sampson; Tzu-Cheg Kao; Steven G Heeringa; Matthew K Nock; Murray B Stein

University of Oxford material

New Journal of Medicine article (registration needed)

Union Leader material

JAMA Network Open abstract

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