PUBLIC HEALTH SURVEILLANCE SURVEILLANCE AND MONITORING z Health

PUBLIC HEALTH SURVEILLANCE

SURVEILLANCE AND MONITORING z Health Surveillance -- the collection, analysis and interpretation of data on individuals or groups to detect the occurrence of certain events and their putative causes for (1) the purpose of prevention or control of certain diseases and other health conditions, (2) formulation of interventions, and (3) evaluation of the impact of programs z Generally, surveillance requires three functions in this sequence: (1) data collection, (2) analysis and interpretations, and (3) decision making

z Surveillance may be performed using data from a variety of sources: z Mortality Data derived from death certificates and population censuses analyze by census tract characteristics such as geographic regions and socioeconomic status of the population z Morbidity and Disability Data derived from regularly available sources such as hospitals, industry and schools. Morbidity and disability data may also be obtained via surveys of representative samples of populations -- e. g. , National Health Interview Survey, BRFSS

z Specially Designed Data Sources such as cancer registries, which combine mortality and morbidity and serve many surveillance uses. For example, time trends for site-specific cancers, cancer control measures, new treatments, and the emergence of rare cancers may be identified and evaluated using cancer registries

z Biologic Characteristics such as population growth, blood pressures, and nutritional status may also be the subject of surveillance -- e. g. , growth of school children made once a year and supplemented by additional information from students and parents on nutritional status, respiratory functions, etc. Allows comparison of such indicators as height and weight of equivalent age groups in successive calendar years as well as the comparison of annual growth rates of various age cohorts

PURPOSES OF PUBLIC HEALTH SURVEILLANCE z Describing trends and the natural (secular) history of health problems z Detecting epidemics z Providing details about patterns of disease z Monitoring changes in disease agents through laboratory testing z Planning and setting health program priorities z Evaluating the effects of prevention and control measures z Detecting critical changes in health practices

z Evaluating hypotheses about the cause of health problems z Detecting rate but important cases of diseases, such as botulism

TYPES OF SURVEILLANCE z Four general categories of public health surveillance z Passive Surveillance y The most commonly practiced disease surveillance at state and local health departments -- generally used standardized reporting cards or forms that are distributed in batches to hospitals, clinics, laboratories and other health care settings y Passive surveillance usually targets physicians, laboratories, and infection control officers y Referred to as passive because no action is taken unless completed reports are received by the public health agency and further public health action is deemed desirable y Completeness of reporting is usually lowest for passive systems, but they tend to be the least expensive to maintain

TYPES OF SURVEILLANCE (cont’d. ) z Active Surveillance y Active surveillance involves an ongoing search for cases y This may involve regular contacts with key reporting sources, such as telephone calls to physicians or laboratories, or a frequent review of data that may include cases of a specific condition, such as a review of laboratory logs for certain bacterial isolates or a review of admissions to burn units to identify severely burned individual y Active surveillance systems may have high levels of completeness but are usually much more expensive to maintain; some question the cost-effectiveness of active surveillance

TYPES OF SURVEILLANCE (cont’d. ) z Sentinel Surveillance y Sentinel surveillance involves the use of a sample of providers -most generally, a sample of physicians or emergency rooms -to identify trends in diseases that occur at relatively high frequencies y E. g. , sentinel surveillance systems, such as those for influenza, provide timely information about trends in influenza-like illness activitiy, and are useful for obtaining information about strains that may be circulating in a community -- assuming that there is a laboratory-based component to the surveillance

TYPES OF SURVEILLANCE (cont’d. ) z Special Surveillance System y Special surveillance systems have been found useful for certain types of surveillance activities y The Behavior Risk Factor Surveillance System (BRFSS) involves administering a questionnaire to a random sample of individuals on a ongoing basis to identify trends in behavior that affect health risk -- e. g. , monitoring the impact of such activities as breast cancer screening with mammography, cervical cancer with pap smears, use of smoke alarms in houses, as well as other health-related behaviors and practices y Mocrobiologic surveys have been useful in determining the antibioltic resistance among persons with invasive pneumococcal infections

THE BEHAVIORAL RISK FACTOR SURVILLANCE SYSTEM (BRFSS) z In 1981, the CDC began helping states and communities to survey adults, 19 years and older, by telephone about their health behaviors z In 1984, the CDC initiated the BRFSS to enable states to collect state-specific behavioral risk factor data z Data are used to estimate the prevalence of behaviors related to the leading causes of death and disability, and are available by such control variables as age, race, sex, income, and education

THE BEHAVIORAL RISK FACTOR SURVILLANCE SYSTEM (BRFSS) z By 1994, all 50 states and D. C. were participating in the BRFSS -- a telephone survey using random-digit dialing and a probability sample of U. S. householdsl z The BRFSS survey instrument consists of: y Core questions asked in all states -- dealing primarily with recent or current behaviors that are risk factors for disease or injury and with quality of life indicators y Standard modules -- sets of questions developed by the CDC on specific topics suggested by states -- each state decides every year which, if any, standard modules they will include y State-specific questions -- included only in a particular state’s survey coverage