Suicide is one of the biggest challenges that psychiatrists face, especially in the emergency room. According to the World Health Organization, there are approximately 3000 suicides every day: one every 40 seconds. About half of all violent deaths in the world are suicides with economic costs of billions of euros. The risk assessment is still based on a subjective approach, with no screening or evaluation tools that support the decision about in-hospital or ambulatory treatment for these patients.

Creation of a decision tree algorithm that can be used in the emergency room to guide the clinical decision.

Increase the number of avoided suicides.

PubMed database was searched and articles with the words “emergency”, “suicide”, “attempt” “screening” and “prevention” were included. Articles that used the most reliable and valid measurement tools (i.e., Beck Scale for Suicide Ideation and Suicide Probability Scale) for patient evaluation were selected. World Health Organization guidelines and the Portuguese Suicide Prevention Plan were analyzed and an algorithm was designed based on the major risk factors identified.

No isolated risk factor was successful for preventing suicide: most are chronic and non-individualized. Having family history of suicide, a mental health disease, a suicide plan and previous suicide attempts are considered major risk factors. The algorithm is based on these factors and takes into account interpersonal variability.

The best way to prevent a suicide is to ask patients for major risk factors, and then, by using this algorithm, treat them accordingly.

The authors have not supplied their declaration of competing interest.