CHAPTER 4 Introduction to Preventive medicine components of disease in symptomatic patients. Most care Much depends on the frequency of the disease in the popula provided by clinicians meets this description. Disability lim tion and the characteristics of the preventive measures tation can be considered prevention because its goal is to halt Tables of the most valuable clinical services are available. slow the disease process and prevent or limit complica- The Partnership for Prevention has been founded as a tions, impairment, and disability. An example is the surgical national not-for-profit health organization dedicated to emoval of a tumor, which may prevent the spread of disease evidence-based prevention grounded in"value. locally or by metastasis to other sites. Discussions about a There are particular challenges to demonstrating bene- patient's disease also may provide an opportunity("teach- fits for preventive measures and achieving meaningful ble moment") to convince the patient to begin health pro oPtion motion techniques designed to delay disease progression (e.g, to begin exercising and improving the diet and to stop A. Demonstration of Benefts smoking after a myocardial infarction Scientific proof of benefits may be difficult because it is often 2. Rehabilitation impractical or unethical to undertake randomized trials of harm using people as subjects. For example, it is impossible form of preve ny are surprised to see rehabilitation designated to assign people randomly to smoking and nonsmoking ention, the label is correctly applied. Rehabi groups. Apart from some research done on animal mode mitigate the effects of disease and prevent some investigators are limited to observational studies, which of the social and functional disability that would otherwise usually are not as convincing as experiments. Life is filled Ls; eay be taught self-care in activities of daily living operate together to produce the levels of health ooscrrd o person to avoid the adverse sequelae associated with pre different subpopulations, making it impossible to infer what longed inactivity, such as increasing muscle weakness that roportion of the improvement observed over time is caused night develop without therapy. Rehabilitation of a stroke by a particular preventive measure. If there is a reduction in patient begins with early and frequent mobilization of all the incidence of lung cancer, it is difficult to infer what pro joints during the period of maximum paralysis. This permits portion is caused by smoking reduction programs and what easier recovery of limb use by preventing the development proportion by the elimination of smoking in workplaces and of stiff joints and flexion contractures. Next, physical therapy public areas, the increase in public awareness of (and action helps stroke patients to strengthen remaining muscle func- against) the presence of radon in homes, and other factors tion and to use this remaining function to maximum effect as yet poorly understood. Lastly, clinical research is expen in performing ADLs. Occupational and speech therapy may sive. A majority of research on treatment and diagnosis enable such patients to gain skills and perform some type of modalities is sponsored by pharmaceutical companies. The gainful employment, preventing complete economic depen- money spent by them to support clinical research is vastly dence on others. It is legitimate, therefore, to view rehabilita- greater than the research dollars spent on prevention. There tion as a form of prevention. fore, some of the lack of data might result from the lack of V. ECONOMICS OF PREVENTION B. Delay of Benefits In an era of cost consciousness, there are increasing With most preventive programs, there is a long delay between demands that health promotion and disease prevention b he time the preventive measures are instituted and the proven economically worthwhile. Furthermore, many people time that positive health changes become discernible itical arena promote prevention as a means of Because the latent period(incubation period) for lung controlling rising health care costs. This argument is based cancer caused by on the belief that prevention is always cost-saving. One way benefits resulting from investments made now in smoking to examine that claim is to look at the cost -effectiveness of tified until many yea various preventive measures and compare them to the cost- have passed. There are similar delays between the time of effectiveness of treatment for existing conditions. smoking cessation and the demonstration of effect for othe As outlined in Chapter 6, cost-benefit analysis compares moking-related pulmonary problems, such as obstructive the costs of an intervention to its health benefits. In order to pulmonary disease. Most chronic diseases can be shown to compare different interventions, it becomes necessary to have long latent periods between when the causes start and express the health benefits of different interventions with the the disease appear ame metric, called cost-effectiveness analysis(Box 14-1) Examples for such metrics are mortality, disease, and costs, C. Accrual of Benefits r their inverse: longevity, disease-free time, and savings. A subtype of cost-effectiveness analysis is cost-utility analysis, Even if a given program could be shown to produce mear which has the outcome of the cost/quality-adjusted life year, ingful economic benefit, it is necessary to know to whom the also called the cost-effectiveness ratio( CER). A recent com benefits would accrue. For example, a financially stressed parison of the CER of various preventive measures with health insurance plan or health maintenance organization treatments for existing conditions found that both prey might cover a preventive measure if the financial benefit tive and curative measures span the cost-effectiveness spec- were fairly certain to be as great as or greater than the cost trum; both can be cost-saving, favorable, or unfavorable 6 of providing that benefit, but only if most or all of the