Epidemiology
Suicide is one of the leading causes of death in the US, Canada, UK, Australia, and New Zealand. Suicide rates in the US have increased significantly since 1999 to a national rate of 13.9 in 100,000 population in 2019.[12] From 2015-2019, an estimated 10.6 million adults in the US (4.3% of the population) reported to have had suicidal thoughts in the preceding year, and 3.1 million adults had made a suicide plan.[13] In the UK, there were 68,357 suicides in the general population between 2010 and 2020, an average of 6215 deaths per year.[14] In the UK, overall suicide rates have fluctuated around 10 in 100,000 per population, but between 2006-2016, the rate of suicide in men aged 45-64 years increased by 17%.[15] Comparison of suicide prevalence rates across countries is difficult due to differences in nature, quality, availability of reporting, data collection, and analysis, but the World Health Organization provides some comparative international data.[16][17] Male suicide rates are highest in post-communist countries such as Lithuania (68.1 in 100,000), Belarus (63.3 in 100,000), and Russia (58.1 in 100,000), whereas female suicide rates are highest in Asian countries such as China (14.8 in 100,000), Korea (14.1 in 100,000), and Japan (13.1 in 100,000).[17] Rate variations are similarly substantial in different regions of the same country, even in the Western world. For example, suicide rates in Canada are 2 to 10 times higher than the national average in some, but not all, First Nation populations.[18] In developed countries, the suicide rate is high for people in midlife and older people, whereas in developing countries it is highest in people aged <30 years.[19] Yearly self-harm rates in one systematic review of older adults with self-harm in hospital-based settings ranged between 19 and 65 in 100,000 people. Self-poisoning was the most commonly reported method of self-harm.[20]
In developed countries, suicide is usually more common among males than among females, but the opposite may be true for suicidal thoughts and certainly for self-harm.[15][21] The higher rate of death by suicide in men compared with women may result from choice of more lethal methods such as firearms and hanging, rather than poisoning or cutting, which are the methods likely to be selected by women.[21][22]
In the UK, suicide is the leading cause of death in young people, accounting for 14% of deaths in 10- to 19-year-olds and 21% of deaths in 20- to 34-year-olds. A UK-based retrospective study found that 6% of adolescents (12- to 17-year-olds) reported self-harm in 2015 in the community (78% female).[23] One large US-based study found that, for adolescents aged 12-17 years, an episode of self-harm in the past year was associated with a 46-fold increased risk of suicide. Factors associated with self-harm in young people in low-income and middle-income countries include bullying, physical violence, loneliness, limited parental support, and alcohol and tobacco use.[24] In developed countries, adolescents identifying as gay, lesbian, bisexual, questioning, or transgender are more likely to self-harm and attempt suicide than their heterosexual/non-transgender peers.[25] A high proportion of the young people who died by suicide had experienced life events such as bereavement, family ill health, suicide loss, bullying, exam stress, neglect, or abuse.[15][26][27] Young people who are inmates also have higher suicide rates than their community counterparts.[28]
Suicide causes a ripple effect with up to 124 people connected with the deceased, including spouses, parents, siblings, friends and acquaintances, coworkers, and healthcare providers.[29]
Risk factors
In general, suicide plans that are premeditated and well thought out usually indicate an elevated risk of suicide.[42] In a sample of British psychiatric hospital inpatients, the odds of death by suicide increased 11-fold given presence of a suicide plan (odds ratio 11.8, 95% CI 1.3 to 111.3).[43] On the other hand, non-disclosure of a suicidal plan does not signify absence of risk.[44]
Although most people who self-harm may not intend to end their life, self-harm is associated with a 50- to 100-fold increased risk of future suicide.[45] The most important predictor of future self-harm is past self-harm.[46][47] With each repetition of self-harm, suicide risk increases.[48] Continued use of weak analgesics to self-poison is a particularly strong indicator of future suicide. After a first episode of self-harm, 20% of people who attend hospital repeat self-harm within a year (many return to the same hospital).[4][49] For children and young people, the link between self-harm and suicide is greater than previously thought, and in the first year after self-harm adolescents and young adults (up to age 24 years) are at markedly increased risk of suicide, especially those who initially used violent self-harm methods.[22] The site of self-injury may also be an important determinant of risk of subsequent suicide.[50]
Up to 90% of people who die by suicide have a psychiatric diagnosis, most commonly major depressive disorder and substance misuse (both alcohol and illicit substances).[51][52] In young people, the relationship between mental illness and suicide is less strong, with only the minority of young people who die by suicide having a diagnosed mental illness. However, all diagnoses of a mental illness carry a risk.[51] Recent use of alcohol in the general population is associated with a significantly increased suicide risk. The risk increases relative to the amount of alcohol consumed.[53]
Access to lethal means significantly increases risk for death by suicide. The retrospective US national mortality survey showed that the odds of suicide increased 28-fold given the presence of a firearm in the home (odds ratio 27.9, 95% CI 18.7 to 41.4).[54] The most lethal means of suicide are firearms, with case-fatality rates of about 90%, followed by hanging, and suffocation.[55] Drug overdose and cutting are less lethal, with case-fatality rates of 2% and 3%, respectively.[55]
One retrospective cohort study found that the odds of a lifetime history of attempted suicide tripled among patients who reported childhood sexual or physical abuse (odds ratio [OR] 3.4, 95% CI 2.9 to 4.0).[56] One meta-analysis of long-term health consequences of child physical abuse, emotional abuse, and neglect reported similar increased risk for suicide attempt (physical abuse [OR = 3.40; 95% CI 2.17 to 5.32], emotional abuse [OR = 3.37; 95% CI 2.44 to 4.67], and neglect [OR = 1.95; 95% CI 1.13 to 3.37]).[57]
Emotional abuse in childhood appears to convey a particularly high risk of self-harm in later life.[58]
History of suicide attempt or death by suicide of a parent has been associated with a nearly twofold increased risk of death by suicide in offspring.[59] One Danish case-control study demonstrated increased suicide risk for patients with a family history of death by suicide (odds ratio 2.58, 95% CI 1.84 to 3.61).[60] Familiality of suicide attempts appears to be explained by a history of mental disorders among those with suicide attempts.[61]
Death by suicide is usually more common among males than among females. However, the rate of lifetime self-harm episodes by women outnumbers the rate in men.[21] Males are less likely to disclose the extent of their distress and seek health care less often for emotional distress.[62]
Death by suicide is usually more common among males than females. In 2019, the suicide rate among males in the US was 3 times the rate for females.[12] However, the rate of lifetime suicide attempts among women outnumbers the rate among men.[21]
The discrepancy between males and females, with respect to death by suicide, may result from method choice because men tend to choose more lethal methods such as firearms and hanging, rather than poisoning or cutting, which are favoured by women.[21] In addition, the higher rate of female suicide attempts may, in part, be due to self-harm behaviours (more common among females) being coded as suicide attempts.
Suicide is frequently reported as the most common cause of death in judicial settings. As a group, inmates have higher suicide rates than their community counterparts. One systematic review of risk factors for suicide in prisoners identified occupation of a single cell, recent suicidal ideation, history of attempted suicide, psychiatric diagnosis, and history of alcohol use problems as most important.[28] In addition, the International Association for Suicide Prevention Task Force on Suicide in Prisons reports that suicide risk among pre-trial inmates is associated with male sex; young age (20-25 years); unmarried status; being a first-time offender arrested for a minor, usually substance-related offense; and intoxication at the time of arrest.[63] In sentenced prisoners, factors associated with suicide include older age (30-35 years), violent offence, having served considerable time in custody (often 4 or 5 years), conflict within the institution or family, a break-up, or a negative outcome relating to their legal status.[63]
Increased rates of suicide have been reported after neurosurgery and in medical diagnoses or physical challenges such as neurodegenerative disease, epilepsy, unspecified organic mental disorders, terminal illness, cancer, pain, asthma, type 1 diabetes mellitus, functional impairment, cognitive impairment, loss of sight or hearing, disfigurement including chronic skin conditions, and loss of independence or increased dependency on others.[52][64][65][66][67][68][69][70] All physical disorders, especially those which are chronic or degenerative in nature, or which disturb sleep, increase the risk of suicide.[52][64][70][71]
One US-based national longitudinal mortality study demonstrated an increased risk for suicide among divorcees, especially men (relative risk 2.47, 95% CI 1.84 to 3.30).[72] One Italian study concluded that being single, divorced, or separated was associated with a higher rate of suicide (odds ratio 2.00, 95% CI 1.87 to 2.16).[73] Married women are at highest risk for suicide in some developing countries, whereas in developed countries suicide risk is higher for divorced, widowed, or separated men.[19]
In general, the lowest-skilled occupations are probably at greater risk of suicide than the highest skill-level group, and unemployed people tend to have a higher suicide rate than those in the workforce.[74][75] One New Zealand study found that people working in farming, fisheries, forestry, and trades had higher suicide rates than people in other occupations.[75] Studies from England and Wales have historically pointed to medical and dental professionals in addition to agricultural occupations. Farmers in India have a particularly high risk of suicide.[76] One Danish study found that suicide risk was reduced in all occupations after adjustment for history of psychiatric admission and socioeconomic factors (employment status, marital status, gross income), with the exception of medical doctors and nurses.[77]
Higher social classes tend to have a lower suicide rate than lower socioeconomic classes.[74] Additionally, unemployment and underemployment have also been linked to increased suicide mortality.[78]
Suicide risk factors associated with psychosocial history include actual/perceived interpersonal loss or bereavement, perceived humiliation, legal difficulties, financial difficulties, changes in socioeconomic status (e.g., job loss), housing problems, work/school issues, family problems, marital/relationship troubles, interpersonal/peer group problems, and domestic violence. In older adults, loneliness, mistreatment, and lack of social support appear to increase the risk of suicide.[79] Social disadvantage, non-intact family of origin, parental psychopathology, and history of childhood physical or sexual abuse have also been studied as risk factors for suicide, especially in youth.[80][81][82] In low- and middle-income countries, the presence of poverty (e.g., diminished wealth and unemployment) is positively correlated with suicidal thoughts and self-harm.[83]
There is emerging evidence that recent bereavement may increase risk, especially in young people.[15][84][85]
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