CLASSIFYING PREVENTIVE INTERVENTIONS FOR PHYSICAL ILLNESS

The original public health classification system of disease prevention was proposed by the Commission on Chronic Illness (1957). It consists of three types of prevention: primary, secondary, and tertiary. Primary prevention seeks to decrease the number of new cases of a disorder or illness (incidence). Secondary prevention seeks to lower the rate of established cases of the disorder or illness in the population (prevalence). Tertiary prevention seeks to decrease the amount of disability associated with an existing disorder or illness. Although the goals of these three types of prevention appear to be clear-cut, in practice there is considerable disagreement about their usage.

The classic example of primary prevention within a public health context was the history-making action in the nineteenth century of John Snow (Last, 1988), who removed the handle of the Broad Street water pump in London to halt the epidemic of cholera in the neighborhood. Despite very little understanding of cause and effect, the prevention effort was successful. Gradually, the knowledge base regarding infectious diseases expanded.

In the original classification system of primary, secondary, and tertiary prevention, there was an implied understanding of mechanisms linking the cause of the disease with the occurrence of the disease. Since the time this system was developed, research has advanced our understanding of the complexity of the association between risk factors and health outcomes. There is an increased appreciation for the importance of the interplay among the biological, psychological, and social, or biopsychosocial, factors in the expression of a physical illness. For the most part, knowledge of the intervening mechanisms is just beginning to be understood.

Recognition of this complex interaction regarding risk and protective factors and illness outcomes, and the lack of understanding about how risk factors lead to or are associated with the onset of illness, sometimes lead to a pessimistic view that prevention efforts are futile until etiology is better understood. Gordon (1987), however, was convinced that practically oriented disease prevention and health promotion programs could be based solely on empirical relationships, and this led him to propose an alternative classification system for physical disease prevention (Gordon, 1987, 1983). The system was based on a risk-benefit point of view; that is, the risk to an individual of getting a disease must be weighed against the cost, risk, and discomfort of the preventive intervention. Gordon's system consisted of three categories: universal, selective, and indicated. All three categories were meant to apply only “to persons not motivated by current suffering” (Gordon, 1983, p. 108). The three categories represented the population groups to whom the interventions were directed and for whom they were thought to be most optimal.

A universal preventive measure is a measure that is desirable for everybody in the eligible population. In this category fall all those measures that can be advocated confidently for the general public and for all members of specific eligible groups, such as pregnant women, children, or the elderly. In many cases, universal preventive measures can be applied without professional advice or assistance. The benefits outweigh the cost and risk for everyone. Examples include maintenance of an adequate diet, use of seat belts, prevention of smoking, many forms of immunization, and prenatal care.

A selective preventive measure is desirable only when the individual is a member of a subgroup of the population whose risk of becoming ill is above average. The subgroups may be distinguished by age, gender, occupation, family history, or other evident characteristics, but individuals within the subgroups upon personal examination are perfectly well. Because of the increased risk of illness, the balance of benefits against risk and cost can be justified. Examples include special immunizations, such as yellow fever, for individuals who travel to areas of the world where the disease is still prevalent, and annual mammograms for women with a positive family history of breast cancer.

An indicated preventive measure applies to persons who, on examination, are found to manifest a risk factor, condition, or abnormality that identifies them, individually, as being at high risk for the future development of a disease. The identification of persons for whom indicated preventive measures are advisable is the objective of screening programs. Gordon meant for the recipients of indicated preventive interventions to be asymptomatic regarding the disease but to have a “clinically demonstrable abnormality.” Indicated preventive measures are usually not totally benign to the subject or minimal in cost. If they were, the balance in the benefit-cost analysis might favor their wider application, including segments of the population at lower risk of disease, and they would tend to move into the selective or universal classes. Examples of indicated measures include medical control of hypertension and frequent, careful examination of persons from whom a basal cell skin cancer has been removed (Gordon, 1983).

Unfortunately, over time there has been a simplistic blending of these two classification systems for the definition of prevention, that is, the original primary, secondary, and tertiary system and Gordon's universal, selective, and indicated system. At times, there even are attempts to use the three-tiered systems interchangeably. This sort of erroneous integration of terms has slipped into the prevention research field and added to the confusion regarding definitions.

Although universal prevention may at times be comparable to primary prevention, indicated measures have been compared to secondary prevention in a very narrow sense that Gordon thought was incorrect. Further, even though the word treatment is often used in connection with indicated preventive measures, Gordon believed that there was a distinction between treatment and indicated prevention. Whereas the aim of treatment is to be immediately therapeutic, the aim of indicated prevention is to provide an intervention for an asymptomatic, clinically demonstrable abnormality that will result in the prevention of some later, anticipated symptoms or disability (Gordon, 1983). While others believed that this “asymptomatic, clinically demonstrable abnormality” was the first sign of illness, Gordon said that these signs were related to the biological origin of disease but were not the disease itself.

This distinction has compelling ethical ramifications. Treatment quickly provides benefits, including symptomatic relief, from an already existing diagnosable condition. On the other hand, indicated preventive interventions are based on probabilities. There is no sure way of knowing that the disease will occur, and potential benefits may be delayed for months or even years. When securing compliance from individuals for indicated interventions, these distinctions should be clarified.

CLASSIFYING INTERVENTIONS FOR MENTAL DISORDERS

Neither the original public health classification system of primary, secondary, and tertiary prevention nor Gordon's classification system of universal, selective, and indicated prevention was designed for use in the prevention of mental disorders. Rather, both focused on prevention of disorders traditionally identified as medical disorders. The application of these terms to a mental health framework is not straightforward. One of the main problems has been the notion of “caseness” that is used in public health. It is often more difficult to document that a “case” of mental disorder exists than it is to document a physical health problem. Agreement regarding the occurrence of a case of a mental disorder varies over time with the instruments and diagnostic systems employed and with the theoretical perspective of the evaluators. Also, symptoms and dysfunction may exist even though all criteria for a DSM-III-R diagnosis are not present. Finally, the outcomes in very young children (birth to age five) are often not diagnosable as “psychiatric caseness” but rather as impairments in cognition and psychosocial development.

The Mental Health Intervention Spectrum for Mental Disorders

Because of all the difficulties described above, the committee has chosen not to use the public health classification system of primary, secondary, and tertiary prevention. Rather, it presents an alternative system in which the term prevention is reserved for only those interventions that occur before the initial onset of a disorder. This system incorporates many of Gordon's ideas regarding prevention, including an adaptation of the concepts selective and indicated.

Although the committee's emphasis is on prevention, it realizes that a classification system is necessary that recognizes the importance of the whole spectrum of interventions for mental disorders—from prevention, through treatment, to maintenance (see Figure 2.1). Under this system, treatment interventions, which are therapeutic in nature (such as psychotherapy, support groups, medication, and hospitalization), are provided to individuals who meet or are close to meeting DSM-III-R diagnostic levels. There are two components in treatment intervention: (1) case identification and (2) standard treatment for the known disorder, which includes interventions to reduce the likelihood of future co-occurring disorders. The optimal treatment protocol aims to reduce the length of time the disorder exists, halt a progression of severity, and halt the recurrence of the original disorder, or if not possible, to increase the length of time between episodes. The clinician also aims to halt the occurrence of other disorders in the patient, a phenomenon known as co-morbidity. Some clinicians see this as a standard part of optimal treatment, whereas others view it as prevention within the original public health classification system. Maintenance interventions, which are supportive, educational, and/or pharmacological in nature, are provided on a long-term basis to individuals who have met DSM-III-R diagnostic levels and whose illness continues (especially the more severe disorders). The two components of maintenance intervention are (1) the patient's compliance with long-term treatment to reduce relapse and recurrence and (2) the provision of after-care services to the patient, including rehabilitation. The aim of both components is to decrease the disability associated with the disorder.

FIGURE 2.1

The mental health intervention spectrum for mental disorders.

By setting prevention into a context within the mental health field, this system helps to point out the fallacy of the commonly voiced idea that prevention is everywhere, in all aspects of mental health research and service. The committee acknowledges that in clinical practice the boundary between prevention and treatment is not as clear-cut as this classification system conveys. Issues of co-morbidity, relapse, and recurrence can be thought of in several ways. For example, providing lithium medication to a patient with bipolar mood disorder is clearly treatment, but if the medication reduces the number and intensity of the depressive symptoms so that the patient is no longer at risk for becoming dependent on alcohol, the intervention may also be thought of as prevention, provided before the onset of a secondary problem, in this case alcohol dependence. Also, psychotherapy for an anxious mother of a healthy child can be conceptualized as treatment of the mother as well as prevention of later difficulties in the child. Finally, effective treatment of a physical illness may prevent a secondary mental disorder and vice versa.

While it is laudable for clinical practice to consider both treatment and prevention outcomes, this report focuses on prevention research as a separate entity. The change in terminology that is used throughout this report, although perhaps not particularly useful to clinicians, who may find themselves providing elements of prevention, treatment, and maintenance to the same patient, is critical to a review of prevention research. Without a system for classifying specific interventions, there is no way to obtain accurate information on the type or extent of current activities, either public or private, and no way to ensure that prevention researchers, practitioners, and policymakers are speaking the same language.

MENTAL HEALTH PROMOTION

The phrase promotion of mental health has definitional problems similar to those of prevention, meaning different things to different people. Norman Sartorius (1988, p. S3), director of the Division of Mental Health at the World Health Organization, noted that “For some, it means the treatment of mental illness; for others, it means preventing the occurrence of mental illness; and for others, promotion of mental health means increasing the ability to overcome frustration, stress, problems, enhancement of resilience and resourcefulness.”

The committee has chosen not to include mental health promotion within the spectrum of interventions focused on mental disorders. Nevertheless, the committee recognizes that mental health promotion activities are important and widespread. The reason for not including it within the above spectrum is that health promotion is not driven by an emphasis on illness, but rather by a focus on the enhancement of well-being. It is provided to individuals, groups, or large populations to enhance competence, self-esteem, and a sense of well-being rather than to intervene to prevent psychological or social problems or mental disorders. This focus on health, rather than illness, is what distinguishes health promotion activities from the enhancement of protective factors within a risk reduction model for preventive interventions. (See Chapter 9 for a theoretical grounding in this perspective on health promotion.)

THE CLASSIFICATION SYSTEM IN PRACTICE

The committee's classification system can be applied to all research and service related to interventions for mental disorders. All three types of intervention—prevention, treatment, and maintenance—are fully compatible with empirical design and measurement and can yield important findings.

As mentioned above, the boundaries between prevention and treatment can be blurred in clinical practice. The same has been true in prevention research. The U.S. Public Health Service's 1984 definition of prevention research includes “only that research designed to yield results directly applicable to interventions to prevent occurrences of disease or disability, or the progression of detectable but asymptomatic disease.” The lack of description of “occurrence,” “disease,” and “disability,” as well as a breakdown of activities into “intervention,” “preintervention,” and “prevention-related research” (see Table 2.1), has led to a wide range of activities being labeled as prevention research. For example, a report to Congress from the Alcohol, Drug Abuse, and Mental Health Administration used this definition to justify the inclusion of everything from basic research to community support programs for the rehabilitation of the seriously mentally ill in its prevention research portfolio (ADAMHA, 1990). The committee recognizes that government officials value the flexibility and broader definition given them and that they are uneasy about targeted mandates from Congress. The committee also recognizes the importance of the whole continuum from basic sciences through treatment research and supports continued research in areas along the entire continuum. However, a too-inclusive definition of prevention research often underlies a neglect of interventions to reduce risks. Therefore the committee presents an alternative, using the term prevention research to refer only to preventive intervention research that can be further classified into universal, selective, and indicated types.

TABLE 2.1

U.S. public Health Service Definition of Prevention Research.

In service, these three general preventive intervention strategies can be integrated within an overall public health plan and are likely to occur in primary health care settings, schools, work sites, churches, and other community settings. For example, universal interventions can be applied when a program is believed to be beneficial for the general public and the benefits outweigh the costs and risks. Targeted campaigns can be mounted to implement selective preventive interventions for high-risk groups and for those individuals with high imminent or lifetime risk factors when the balance of benefits against risk and cost can be justified. Should individuals at risk begin to show early symptoms of the disorder, they would be candidates for an indicated preventive intervention program designed to avert the full-blown manifestation of the disorder through more intensive and focused preventive strategies. In a public health approach, each level of preventive intervention would be keyed to the nature of the target population's needs for reducing risk factors and strengthening protective factors.

Also within the public health care plan, adequate treatment and after-care interventions need to be readily available for those who have not had access to preventive interventions or for whom the interventions were not effective in preventing the onset of a mental disorder. Although the focus in this report is on prevention, the other components of the classification system outlined here deserve equal emphasis in a comprehensive and coordinated new approach to our nation's mental health.

REFERENCES

• ADAMHA (Alcohol, Drug Abuse, and Mental Health Administration). (1990) Report on Programs and Plans in Prevention. Rockville, MD: Department of Health and Human Services.
• Commission on Chronic Illness. (1957) Chronic Illness in the United States. Vol. 1. Published for the Commonwealth Fund. Cambridge, MA: Harvard University Press.
• DHEW (Department of Health, Education, and Welfare). (1979) Healthy People: The Surgeon General's Report on Health Promotion and Disease Prevention. Office of the Assistant Secretary for Health and Surgeon General. Washington, DC: Public Health Service. DHEW (PHS) Pub. No. 79–55071.
• Gordon, R. (1987) An operational classification of disease prevention. In: J. A. Steinberg, editor; and M. M. Silverman, editor. , Eds. Preventing Mental Disorders. Rockville, MD: Department of Health and Human Services; 20–26.
• Gordon, R. (1983) An operational classification of disease prevention. Public Health Reports; 98: 107–109. [PMC free article: PMC1424415] [PubMed: 6856733]
• Last, J. M., Ed. (1988) A Dictionary of Epidemiology. New York, NY: Oxford University Press; 122.
• Sartorius, N. (1988) Health Promotion Strategies: Keynote Address. Canadian Journal of Public Health; Suppl. 2; 79: S3–S5. [PubMed: 3242787]