In 2019, there were 47,511 reported suicide deaths in the United States, making it the 10th leading overall cause of mortality [1]. Every day, approximately 130 Americans take their own life, and one person dies by suicide every 11.2 minutes. An estimated 90% of persons who die by suicide have a diagnosable psychiatric disorder at the time of death, although only 46% have a documented diagnosis [2,3].

Suicide rates vary according to race, ethnicity, sex, and many other factors, including age [8]. In almost every country, suicide is predominated by male victims, with the exception of China, which is the only country in which the female suicide rate (14.8 per 100,000) exceeds the male rate (13 per 100,000) [9]. In the United States, the number of deaths by suicide is nearly four times greater among men (37,256) than among women (10,255). Overall, suicide accounts for 1.7% of all deaths in the United States and a death rate of 13.9 per 100,000 [1].

A woman takes her own life every 51.25 minutes in the United States [1]. Suicide is more common among women who are single, recently separated, divorced, or widowed, and the suicide rates for women peak between the ages of 45 to 64 years. Precipitating life events for women who attempt suicide often involve interpersonal losses or crises in significant social or family relationships. As noted, more women attempt suicide than men, and there is a 2 to 3:1 ratio of women versus men with a history of attempted suicide. The higher rates of attempted suicide among women are likely due to the higher rates of mood disorders such as major depression, persistent depressive disorder (dysthymia), and seasonal affective disorder. Factors that may contribute to the lower rates of suicide deaths in women relative to men include stronger social supports, feeling that their relationships are a deterrent to suicide, differences in preferred suicide method, and greater willingness to seek psychiatric and medical intervention [2,13].

Most adolescent suicides occur at home after school hours. Adolescent nonfatal suicide attempters are typically girls who ingest pills, while those who die by suicide are typically boys who die from gunshot wounds. Intentional self-harm should be considered serious and in need of further evaluation because not all adolescent attempters admit their intent. Most adolescent suicide attempts are triggered by interpersonal conflicts and are motivated by the desire to change the behavior or attitude of others. Repeat attempters may use this behavior as a coping mechanism for stress and tend to exhibit more chronic symptomatology, worse coping histories, and higher rates of suicidal and substance abuse behaviors in their family histories [13]. The presence of multiple emotional, behavioral, and/or cognitive problems may be a more important predictor of suicide behavior risk than a specific type of problem (e.g., an addictive behavior or an emotional problem) [13,33]. The presence of acne is associated with social and psychologic problems, and certain acne medications have been linked with an increased risk of suicidal ideation [36].

The elderly account for roughly 19.3% of suicides but only 16% of the population [13]. Suicide rates rise with age for men, especially after 65 years of age, and the suicide rate in elderly men is 5 times that of same-aged women; more than 85% of elderly suicides are among men [13,35]. The overall rate of elderly suicide is nearly 20 per 100,000. However, the rate is 40 per 100,000 among elderly White men and 51.8 per 100,000 among White men older than 85 years of age, a rate that is almost 2 times the rate for men of all ages. In contrast, the suicide rate of women declines after 60 years of age [13,35].

Although undiagnosed and/or untreated depression is the primary cause of suicide in the elderly, suicide completion is rarely preceded by only one factor. Risk factors for suicide in this population include a previous suicide attempt; mental illness; physical illness or uncontrollable pain; fear of a prolonged illness; major changes in social roles, such as retirement; loneliness and social isolation (especially in older men who have recently lost a loved one); and access to lethal means, such as firearms in the home [13].

LGBT+ youth generally have more risk factors, more severe risk factors, and fewer protective factors, such as family support and safe schools, than heterosexual youth. There are also risks unique to this population related to sexual orientation, such as disclosure to family or friends [13]. The impact of stigma and discrimination against LGBT+ individuals is enormous and is directly tied to risk factors for suicide such as isolation, alienation and rejection from family, and lack of access to culturally competent care [43]. Family connectedness, perceived caring from other adults, and feeling safe at school were reported as significant protective factors in a survey of 6th-, 9th-, and 12th-grade LGBT+ students [37,38]. It has also been noted that LGBT+ adults have a two-fold excess risk of suicide than their heterosexual counterparts [37].

Several protective factors against suicide behavior have been identified [5,62]. These include:

In addition to risk factors specific to special populations, there are many general risk factors common among most populations. General biopsychosocial risk factors include [2,5,62]:

At least 90% of people who die by suicide have diagnosable psychiatric illness [2,3]. The psychiatric conditions with the greatest association with suicidal behavior are depression, bipolar disorder, substance abuse, schizophrenia, and personality disorders.

Major depression is the psychiatric diagnosis most commonly associated with suicide. The risk of suicide in persons with major depression is roughly 20 times that of the general population [13]. About 30% of all patients with major depression attempt suicide, half of whom ultimately take their own lives [63]. More than 60% of persons who die by suicide are clinically depressed at the time of their deaths, although this climbs to 75% when patients with comorbid depression and alcohol use disorder are added. Seven of every 100 men and 1 of every 100 women diagnosed with depression will die by suicide [13].

Alcohol and drug abuse are second only to depression and other mood disorders as conditions most associated with suicide. Substance use disorders and disordered mood are often comorbid. The suicide risk among patients with alcohol use disorder is 50% to 70% higher than the general population. Alcohol abuse is a factor in roughly 30% of suicides, and about 7% of persons with alcohol dependence die by suicide [2,13,68].

In 2011, an estimated 228,366 emergency department admissions were made for alcohol- or drug-related suicide attempts. Almost all (94.7%) involved either a prescription drug or an over-the-counter medication [69]. Approximately 64.4% involved multiple drugs, and 29% involved alcohol [69].

Divorced, widowed, and single people have a higher suicide risk. Marriage appears to be protective for men, but not so for women. Marital separation also increases the risk of suicide [59,60].

Certain occupational groups, such as veterinary surgeons, pharmacists, dentists, farmers, and medical practitioners, have higher rates of suicide. Although obvious explanations are lacking, access to lethal means, work pressure, social isolation, and financial difficulties may account for the heightened risk [59,60].

Unemployment and suicide are also correlated, although the nature of the association is complex. Poverty, social deprivation, domestic difficulties, and hopelessness likely mediate the effect of unemployment, but persons with psychiatric illness and personality disorders are also more likely to be unemployed. Recent job loss is a greater risk factor than long-term unemployment.

Approximately 20% of people who kill themselves had made a previous attempt, making previous serious suicide attempts a very high risk factor for future attempts [2].

Veterans and military members often possess many risk factors for attempting or completing suicide. This includes combat exposure (particularly deployment to a combat theater and/or adverse deployment experiences), combat wounds, post-traumatic stress disorder (PTSD) and other mental health problems, comorbid major depression, traumatic brain injury, poor social support, feelings of not belonging or of being a burden to others or society, acquired ability to inflict lethal self-injury, and access to lethal means [52,58,81,82,83]. There is conflicting evidence of the role of PTSD in suicide risk, with some studies finding PTSD diagnosis to be protective while others indicated it increased risk. Other possible risk factors include [79,123]:

Most people who are suicidal exhibit warning signs, whether or not they are in an acute suicide crisis. These warning signs should be taken seriously and include observable signs of serious depression, such as unrelenting low mood, pessimism, hopelessness, desperation, anxiety, psychic pain, and inner tension; withdrawal from friends and/or social activities; sleep problems; and loss of interest in personal appearance, hobbies, work, and/or school [2,13]. Other signs include:

Intentional self-harm is behavior related to, but distinct from, suicide behavior and includes suicide attempts and nonsuicidal self-injurious behaviors, such as burning, cutting, and hair pulling, that does not have fatal intent [85]. Self-injurious behavior falls into three categories [85]:

In the United States in 2019, use of a firearm was the cause of death in 50.4% of suicides and is the number one means among all individuals 15 years of age and older. Gun use accounts for 47% of all suicide deaths in individuals 15 to 24 years of age, reaching a low of 42.1% in those 35 to 44 years of age, and increasing to 51.8% in those 55 to 64 years of age. Firearm use for suicide completion is extremely high among the elderly, with individuals 75 to 84 and 85 years of age and older having the highest rates, at 75.4% and 76.6%, respectively. Gun use is also the most common suicide method among youth, accounting for 31.5% of all suicide deaths [1,78].

Healthcare providers may encounter a patient they suspect is suicidal. This suspicion may be prompted by the presence of one or more of the risk factors for suicide described previously, patient history, a statement expressed by the patient, or by their intuition. This scenario may present a dilemma of how to proceed. Although some healthcare professionals are uncomfortable with suicidal patients, it is essential not to ignore or deny the suspicion of suicide risk. The first and most immediate step is to allocate adequate time to the patient, even though many others may be scheduled. Showing a willingness to help begins the process of establishing a positive rapport with the patient. Closed-ended and direct questions at the beginning of the interview are not very helpful; instead, use open-ended questions such as, "You look very upset; tell me more about it." Listening with empathy is in itself a major step in reducing the level of suicidal despair and overall distress [59,60]. It is helpful to lead into the topic gradually with a sequence of useful questions, such as [59,60]:

Understanding the interactive relationship between risk and protective factors in suicidal behavior and how this interaction can be modified forms the basis of suicide prevention [5,106]. The characteristics shared by effective suicide prevention programs include clear identification of the intended population, definition of desired outcomes, use of interventions known to effect a particular outcome, and use of community coordination and organization to achieve an objective. Prevention efforts are based on a clear plan with goals, objectives, and implementation steps [5,45].