Dr. Eve Mościcki reviewed the risk factors for completed and attempted suicide, highlighting those with the most promise for prevention. Her presentation focussed on population-based studies, rather than clinical studies. The vital statistics collected by the Centers for Disease Control, via the ICD-9 classification system, were her primary source. The other data Dr. Mościcki discussed are drawn from population-based psychological autopsy studies.

Dr. Mościcki stated that our current reporting system for suicide is not uniform. It is split approximately evenly between two systems: the medical system where the person signing the death certificate is a medical examiner with a medical degree, and the legal system where the person signing the death certificate is a public official, often elected and with a judicial degree. In seventeen states the system is mixed, with different counties using medical or legal systems. Criteria for classification of suicide deaths were developed in the late 1980s via a task force convened by the American Association of Suicidology. The need to address both lethality and intent as part of an operational definition of attempted suicide was identified as one of the major classification issues. The agreed-upon classification system is still not uniformly applied, which leads to in-consistencies across jurisdictions. Yet Dr. Mościcki expressed the belief that, in general, the classification system works, and “by and large we can be fairly confident that when a death is classified as a suicide, that it is a genuine classification.”

In 1998 suicide was the eighth leading cause of death. The age-adjusted rate was 10.4 per hundred thousand (as compared to the leading cause of death, diseases of the heart at a rate of 127 per hundred thousand). The suicide rate has declined very slowly since the time of the adoption of the ICD-9 coding system in 1979. There are differences in rates across states, and across sub-groups within the U.S. population. Western and frontier states have the highest suicide rates, with the lowest rates in the mid-Atlantic states. For example, Alaska had the highest, and New Jersey the lowest rate in 1998. There are striking differences in rates across racial and ethnic groups, and across gender. Men, older people and Americans of European decent have higher rates of suicide. Widowed persons have higher rates of suicide than married people. There are similarities between rates across the lifespan for African American men, Native Americans, and Alaska Natives: the rates are higher in the younger age range. In contrast, the peak for Caucasian men is during old age. Women do not show large rate changes over the life-span; there is no peak for women of any race or ethnicity.

The suicide rates in the U.S. are largely driven by rates for white men.

Eve Mościcki

Dr. Mościcki reported that the mechanism of choice in the United States is firearms. Among men, firearms account for about 62 percent of all suicide deaths; among women, about 39 percent. Hanging and self-poisoning are the distant second and third mechanisms of death.

Dr. Mościcki noted that there are few national data on rates of suicide attempts. Estimates for life-time prevalence range from 1 percent to over 7 percent. The 12-month prevalence estimates range from about 0.2 to 2.6 percent. Women report greater rates of attempted suicide than men across the lifetime, but no significant difference is found when asking about recent attempts. Younger people, those with lower educational achievement, and previously married persons (as compared with married) all have higher rates of suicide attempts. The data from one of the studies, The National Co-Morbidity Study, investigated the degree of intent of the non-fatal attempts, and found that approximately half of the attempters indicated they did not really intend to die.

The current data indicate that suicide is the result of interactions among risk and protective factors. Risk factors can be broken down into distal (underlying vulnerability) and proximal (precipitants), which is an important distinction in terms of prevention strategies because the strategy will be different depending on the category of risk being targeted.

The primary risk factor for suicide is psychopathology.

Eve Mościcki

The co-occurrence of distal and proximal risk factors leads to the necessary and sufficient conditions for attempted or completed suicide. Strong epidemiologic evidence suggests that psychopathology is the most critical distal risk factor for suicide. Over 90 percent of completed adult and 67 percent of completed youth suicides meet diagnostic criteria of a psychiatric diagnosis. Psychopathology has also been found in the large majority of serious suicide attempts in the few published case-controlled studies. The most common diagnoses are mood disorders, substance abuse disorders, personality disorders, and schizophrenia. Dr. Mościcki stated that although there is a consistent high association between psychiatric and addictive disorders with suicide, it remains undetermined whether suicide is the result of the severe expression of these disorders, or a separate, overlapping entity. One of the reasons it remains unclear whether suicide is distinct from psychiatric disorders is that the vast majority of studies use post-mortem diagnoses (psychological autopsies), and do not ascertain whether the diagnosis could still be made if the suicide had not occurred. This leads to the possibility of over-diagnosis of depression.

Co-morbidity, the presence of more than one psychiatric or substance abuse disorder, is also an important risk factor. Of the psychological autopsies examining co-morbidity, 70–80 percent of completed suicides were found to have co-morbid conditions, with the most common being mood disorders and alcohol abuse. In the elderly, mood disorders are often co-morbid with a physical disorder, but physical illness does not appear to independently increase risk. Similarly, panic disorder in conjunction with depression may be a signal for suicide risk, but it does not appear to be an independent risk factor as had been previously thought.

Other distal risk factors for suicide are neurochemical abnormalities, the most prominent of which is serotonin system dysfunction. This is independent of psychiatric diagnosis and associated with subjective severity of symptoms and a history of planned and medically lethal suicide attempts. Reduced levels of cholesterol have also been associated with risk for suicide. Dr. Mościcki reported that family history of psychopathology and suicidal behavior is a risk factor that might function by altering biological vulnerability and serotonin functioning. Additionally, family history represents a genetic contribution to underlying biological factors. A dysfunctional family environment with multiple stressors has been shown to contribute to suicidality.

…the nature of the stressor may be less important than the actual number of stressors. The greater the number of stressors in a person's life, the higher the suicide risk.

Eve Mościcki

Dr. Mościcki went on to review the proximal risk factors for suicide. She stated that “…the presence of firearms in the home is a primary proximal risk factor for completed suicides.” Additionally, availability of prescription medications can be a risk factor in elderly populations.

Stressful life events can also precipitate suicidal behavior, though an individual's perception of stress is highly subjective and determines the extent to which the stress increases suicide risk. Thus, the type of stressor varies across the lifespan as individuals' perceptions change. An intense stressor in a young person might be a relationship loss or a humiliating experience, while in an older person it is more likely to be the death of a spouse, suspicion of a terminal illness, perceived loss of independence, or sudden disability. Dr. Mościcki reported that the nature of the stressor appears to be less important than the number of stressors; a greater number of stressors results in higher suicide risk.

Intoxication, outside of a substance abuse diagnosis, is an immediate risk factor for suicide. Fifty percent or more of all completed suicides are intoxicated at the time of death. Contagion is another potential precipitant to suicide, particularly in young people. However, the effect of contagion in murder-suicides is less clear, since many of the reports are anecdotal and thus make generalizing difficult. Incarceration can be a precipitant to suicide as well; so much so that suicide is the leading cause of death in jails. Because individuals who end up in jails often have a higher number of distal risk factors as well, this is a complex causal relationship. Many incarcerated persons have some form of psychopathology, and Dr. Mościcki stated “…increasingly in this country the justice system has become a de facto service system for mentally ill persons.”

A debate exists about the proposed risk factor of sexual orientation. Dr. Mościcki reported that the evidence for sexual orientation as an independent risk factor for suicide is lacking. Suggestive evidence exists for rising rates of attempts in gay and lesbian youth; however, no research has been done that controls for underlying psychopathology. Two psychological autopsy studies have been done and have not found an increased risk with any sexual orientation. Dr. Mościcki stressed the need for more work in this area.

Dr. Mościcki concluded her talk with several recommendations for the future of the epidemiology of suicide. They were: (1) Increase the integrative research on the interaction between individual and environmental factors. (2) Increase research on the protective factors against suicidality. (3) Expand knowledge on suicide morbidity and mortality in minority populations. The protective factors found in these populations may translate into preventive interventions. (4) Increase understanding of the cultural context of suicide risk and prevention. (5) Standardize the nomenclature for suicidal behaviors. (6) Clarify the relationships of medical illness, panic attacks, prescription medications, and sexual orientation with suicide risk. (7) Develop improved models to predict imminent suicides. (8) Identify the implications for preventive interventions in the current knowledge base. Dr. Mościcki stated that her talk suggested two systematic environmental interventions: reduced psychiatric and substance abuse morbidity through better identification and appropriate treatments; and limited access to firearms. (9) Increase work on the development, testing, and dissemination of empirically-based preventive interventions, with rigorous testing for safety, efficacy, and transportability. (10) Consider the public health and policy relevant outcomes of interventions.