Epidemiology of completed and attempted suicide: toward a framework for prevention

Abstract

Suicide is an important public health problem. It is a complex, long-term outcome of mental illness, with multiple, interacting antecedents. This paper reviews descriptive and analytic epidemiologic studies of completed and attempted suicide, discusses the primary sources of epidemiologic data, and describes the major risk factors for completed and attempted suicide. Risk factors are described within a framework that distinguishes between distal and proximal, and individual and environmental antecedents. Organization of our knowledge of risk and protective factors for both completed and attempted suicide provides opportunities to develop and implement life-saving preventive strategies.

Introduction

Suicide is a complex and tragic outcome of mental illness. It is an important public health problem [1], not only because of the loss of over 30 000 lives per year, but because the death by suicide of a single individual can have a devastating effect on the lives of those left behind [2]. Yet suicide is preventable.

By organizing our knowledge of suicide, we can begin to focus our prevention efforts. Emile Durkheim, one of the first to scholars to investigate suicide systematically, examined suicides in France through a sociodemographic lens toward the end of the 19th century. He demonstrated that suicide is not a unidimensional occurrence, but differs among population subgroups [3]. One hundred years later, at the end of the 20th century, attention has focused on depression, substance abuse, and suicide as leading causes of death and disability [4]. The dawn of a new millennium witnesses our progressively sophisticated knowledge base of basic, clinical, and epidemiologic research on suicide. This solid scientific foundation, along with a growing public recognition and desire for action to save lives [5], has brought ever-increasing hope that we can, indeed, prevent suicide.

Suicidality occurs on a continuum of severity that progresses from less serious and more prevalent behaviors through increasingly severe, less prevalent, and more lethal behaviors [6], [7], [8], [9]. At one end are behaviors such as casual ideation without specific plans. These behaviors may progress in some individuals through persistent, intense ideation that includes a plan, self-inflicted injury without intent to die, and, for a very small proportion of persons at the other end of the continuum, to a suicide attempt with high lethality, and completion [6], [10], [11].

The discipline of epidemiology, which studies health and illness in human populations [12], has contributed some of the primary tools used by scholars who study suicide from a public health perspective. Descriptive epidemiologic studies examine patterns of the occurrence and distribution of diseases and other health-related outcomes in populations according to sociodemographic characteristics such as age, sex, race, or social class, geographic area, and time, thus providing information on the scope and impact of disease [13]. The data from such studies complement descriptive findings from clinical observations, basic research, and other sources of information, and are used to generate causal hypotheses. Causal hypotheses are tested in analytic epidemiologic studies, which examine the relationships between antecedent exposures and health outcomes [12]. A major contribution of epidemiologic studies of both clinical and community populations is not only to identify antecedent exposures as independent risk or protective factors, but also to quantify the strength of their relative contribution to the risk of disease or disorder [14]. Understanding the potency of risk factors for complex outcomes such as suicide and suicidal behaviors provides a way to prioritize prevention efforts and wisely invest limited prevention resources.

The purpose of this paper is to provide a review of descriptive and analytic epidemiologic studies of completed and attempted suicides, with the goal of identifying opportunities for prevention.