Principles and practice of Secondary prevention cost-effective; this explains the popularity of mobile imaging vans that offer full-body computed tomography(CT)and COMMUNITY SCREENING 96 A. Objectives of Screening 196 he direct-to-consumer marketing of genomic analysis. In contrast, many entive medicine alists demand the B. Minimum Requirements for Community Screening same standards of evidence and cost-effectiveness as for 97 . Disease Requirements 197 therapeutic interventions in patients with known disease. A 2. Screening Test Requirements 198 case may be made for even higher standards. Screening 3. Health Care System Requirements 198 means looking for frouble. It involves, by definition, people 4. Application of Minimum Screening Requirements to Spe with no perception of disease, most of whom are well; there- fore great potential exists to do net harm if screening is performed haphazardly. C. Ethical Concerns about Community Screening 199 D. Potential Benefits and Harms of Screening Programs 199 E. Bias in Screening Programs 200 which is the process of searching for asymptomatic diseases F. Repetition of Screening Programs 20 and risk factors among people in a clinical setting (i.e among people who are under medical care). If a patient is for Multiple Diseases(Multiphasic Screening)201 being seen for the first time in a medical care setting, clini cians and other health care workers usually take a thorough H. Genetic Screening 202 medical history and perform a careful physical examination lL. INDIVIDUAL CASE FINDING 202 and, if indicated, obtain laboratory tests. Establishing base A. Periodic Health Examination 202 line findings and laboratory values in this way may produce B. Health Risk Assessments 203 case finding, if problems are discovered, and is considered III. SCREENING GUIDELINES AND “ good medicine” but is not referred to as“ screening RECOMMENDATIONS 203 a program to take annual blood pressure of employees of IV, SUMMARY 204 a business or industry would be considered screening, REVIEW QUESTIONS, ANSWERS, AND EXPLANATIONS ius Thereas performing chest radiography for a patient who w st admitted to a hospital for elective surgery would be called"case finding. The distinction between screening and case finding is frequently ignored in the literature and in practice. Most professional societies do not distinguish between the two in their recommendations regarding screen- Secondary prevention is based on early detection of disease, ing. We use the two terms interchangeably in this chapter through either screening or case finding, followed by treat Chapter 7 discusses some of the quantitative issues involved ment Screening is the process of evaluating a group of in assessing the accuracy and performance of screening, people for asymptomatic disease or a risk factor for develop- including sensitivity, specificity, and predictive value of tests ing a disease or becoming injured. In contrast to case finding In this chapter we assume the reader is comfortable with defined later), screening usually occurs in a communi hese concepts. The purpose here is to discuss broader publi setting and is applied to a population, such as residents of a health issues concerning screening and case finding. Chapter county, students in a school, or workers in an inau Istry. 18 provide n extensive discussion of the u.s. pr reventive Because a positive screening test result usually is not diag- Services Task Force in the clinical encounter. nostic of a disease, it must be followed by a diagnostic test For example, a positive finding on a screening mammogram examination must be followed by additional diagnostic I. COMMUNITY SCREENING g or a biopsy to rule out breast cancer. As shown in Figure 16-1, the process of screening is A. Objectives of Screening complex and involves a cascade of actions that should follow if each step yields positive results. In this regard, initiating a Community screening programs seek to test large numbers screening program is similar to boarding a roller coaster; of individuals for one or more diseases or risk factors in a participants must continue until the end of the process is community setting(e. g, educational, work, recreational)on reached. Many members of the public assume that any a voluntary basis, often with little or no direct financial screening program will automatically be valuable or outlay by the individuals being screened(Table 16-1)