Prevention Health Article

THE CONTEXT OF PREVENTION

Prevention takes place at almost all important societal venues, which may be considered in a few major categories (although there is overlap among them): (1) prevention that is facilitated by a healthful environment; (2) prevention optimized by healthful personal behaviors; (3) preventive interventions delivered by health professionals—socalled clinical prevention; and (4) prevention that occurs through social actions, including political, policy, economic, educational, and other group behaviors.

Examples of each preventive venue is instructive. A healthful physical and biological environment is attained when known harmful agents are eliminated, such as lead, automotive exhaust gases, asbestos particles, and viral infectious particles. However, it is very difficult to determine the risks to health of small amounts of certain environmental agents, naturally occurring or contaminants, and risk assessment methods may be employed. Healthful personal behaviors, such as regular, appropriate exercise programs and avoiding risk-taking behaviors, such as tobacco or illicit drug use, will add measurably to positive preventive outcomes. Clinical preventive interventions, such as cancer screening, clinical health counseling, and routine immunizing practices, will add important elements of prevention to individuals and families. Finally, social and administrative activities provide some of the best prevention available in communities. Examples include providing laws that deter underage alcohol and tobacco consumption, health system policies that promote early disease detection, and taxation policies that deter purchase of harmful products such as cigarettes and firearms. All prevention activities work in concert to provide as safe and healthful an environment as possible, but, as noted below, the secondary consequences of each activity should be understood as much as possible.

DISEASE PREVENTION AND HEALTH PROMOTION

Disease prevention is often distinguished from health promotion. While the absence of important conditions is a most worthy goal, it is also useful to consider the attainment of positive health states, where not only are clinical conditions not present, but the highest levels of physical, mental and social well-being are attained. The term "health promotion" has been used to encompass interventions and behaviors that prevent diseases, but many of these same activities can be valuable for attaining the most positive functional performances, emotional attitudes, and states of well-being, irrespective of disease occurrence and risk. Some of this may be obtained by abstinence from tobacco, regular exercise programs, consumption of lower fat diets, and provision of educational opportunities. An additional term often used in public health is "health protection." This term has been used in several contexts, but often encompasses both health promotion and disease prevention, and usually refers to the programmatic and regulatory structures that are designed to limit harmful exposures and enhance health status of particular groups or the general population.

THE POSITIVE AND NEGATIVE EFFECTS OF PREVENTIVE INTERVENTIONS

The goals of prevention would be argued by few. Fundamentally, nearly all would agree that avoiding diseases, disability, and suffering would be beneficial for the health of individuals and the public. However, the methods of prevention, even if based in scientific studies of proven efficacy and effectiveness, can be contentious, and where explicit policy, practice, or programmatic interventions are instituted, there may be substantial fiscal costs to individuals and society, as well as adverse effects and moral or ethical disputes as to the appropriateness of the interventions. It is likely that all major activities and environmental exposures in all societies have both positive and adverse effects on individual and community health, and understanding the trade-offs can be a difficult but necessary dimension of prescribing prevention programs. To elaborate this principle, examples are offered for various elements of prevention:

• Routine childhood vaccines eliminate a substantial amount of disease and death, but occasionally have important adverse effects on the health and well-being of some individuals.
• Many medications that are used for disease prevention, such as those which treat hypertension or hypercholesterolemia, will have predictable and well-established adverse drug reactions that can limit their use.
• Screening for early and asymptomatic diseases will often lead to decreased morbidity and mortality from those diseases, but the screening maneuvers may lead to occasional serious adverse effects, such as perforation of the intestine during colonoscopy. Also, since most screening tests are not perfectly accurate, it is possible that someone might be incorrectly told that a test showed no abnormality when one actually exists—this individual may take inappropriate actions based on this inadvertently false or misleading information.
• Various mechanical devices will enable some disabled individuals to extend their functional range, but the device itself might lead to occasional injuries to that individual or to others assisting him. For example, there is a real and detectable injury rate due to wheelchair use. Such use may be appropriate, but may have incumbent adverse effects.

Thus, it is important for preventive interventions not only to be effective, but also that the cost-effectiveness and benefits of these interventions be understood. Without this, the net health change may not necessarily be positive.

Some preventive interventions are controversial not because they cause some adverse effects or because they don't always work, but rather because they inadvertently promote some level of the behavior or condition they are trying to prevent. This general problem falls under a phenomenon called "harm reduction." While somewhat over-simplified, the following are examples of when and how this occurs:

• The promotion of cigarettes that may confer less exposure to certain carcinogens and other toxins may reduce the risk of some smoking-related conditions, but fail to dissuade some persons to quit smoking altogether because of the perception that the cigarette is "safer," when in fact it may not be very safe and the overall effect is negative.
• Needle exchange programs, which are intended to supply drug addicts with uncontaminated needles that would decrease the risk of blood-borne infections such as AIDS (acquired immunodeficiency syndrome) or hepatitis may be beneficial to those who avail themselves of this program, but may allow more needles to be available to others. How these needles would be used by others is sometimes uncertain. The existing evidence suggests that needle exchange programs do not promote illicit drug use.
• Similarly, the distribution of condoms to demographic or other groups at high risk of sexually transmitted diseases and unwanted pregnancies may be a preventive for some, but others are concerned that this may promote increased sexual activity, with its own health and moral dimensions.

Thus, it is possible that certain preventive interventions are helpful to those who use them, but in theory, the net benefit to the population's health may not be as great as otherwise would be anticipated. The trade-offs and secondary consequences thus should be understood for any preventive maneuver.