KR Tutorial Module 3

Public health information or data are central to public health’s mission of improving health and preventing disease, injury and disability.(1) Each of the programs or domains addressed through public health rely on information to inform program design, monitor progress, fulfill reporting requirements, bill for services, evaluate programs and inform policy decision making. (See Modules 1 and 2 for more detail on the definition of public health and the structure and function of public health agencies.) Examples of public health programs or domains that create and utilize public health data include:

There are various types of data and databases that support public health programs. Data are divided into two forms: qualitative and quantitative.

Quantitative data are measurable and tangible. They involve the counting of people, behaviors, conditions, or other events; classifying those events into categories; and using math and statistics to answer questions.(2) The number of smokers and nonsmokers by gender in a particular geographic area would be considered quantitative data.

Qualitative data are collections of perceptions, attitudes, observations, and context, instead of the collection of numbers or statistics found in quantitative data. The information developed from these data helps to understand the root causes and precursors of health problems identified through quantitative data. Observations from a high school smoking cessation group about what causes them to smoke is an example of qualitative data.(3)

In addition, data that support public health programs may reside in many more entities than just public health organizations. In most cases, they exist across a public health system (See Exhibit 1). For example, much of the success in lowering the incidence of lead poisoning can be attributed to the use of coordinated, multiple sources of public health data that reside both in and outside of public health agencies, e.g., public health environmental data, clinical laboratory data, encounter data from mental health professionals, and housing data.

The remainder of this module describes various types of quantitative public health data and databases. (See Module 4 for more information on using public health data.)

Administrative data are information generated through overseeing public and private health insurance, enrolling members, paying bills, and other administrative activities. Public health relies on administrative data to provide services and make decisions, including financial data, facility and personnel data, and utilization or encounter data.

Financial data include, but are not limited to, the documentation of the charges for services, costs of providing services, revenues generated from services and revenues from other sources. State agencies must collect financial data for administering programs such as Medicaid. The Centers for Medicare and Medicaid Services (CMS) requires Medicare certified hospitals to report cost data.

Facility data include information on the characteristics of various health related resources, including where these resources are located, whether they are licensed, etc. State departments of health often maintain directories of facilities as well as license facilities, such as long term care and health maintenance organizations.

As services are utilized, information on those encounters are recorded to acknowledge occurrence, facilitate billing and payment, and analyze patterns of service delivery. Encounter data are a rich source of administrative as well as clinical information. Public health agencies, hospitals and health systems, and public and private payers all collect encounter data. When public health services, such as prenatal care, WIC services, or dental services, are provided, data are usually recorded by hand in an individual’s chart and, in some cases, aggregated at a later date into databases. Hospitals and health systems also collect data on various types of encounters for inpatient care, emergency department services, home health care, and other services. Hospital inpatient discharge data, in particular, are used often in public health analyses. These data are very accessible as a result of state initiatives to aggregate hospital discharge data across hospitals. Data are also collected by physicians to account for office visits and by public payers for programs like Medicaid, the State Children’s Health Insurance Program, and workers’ compensation.

According to the Agency for Toxic Substances and Disease Registry, a registry is "a system for collecting and maintaining, in a structured record, information on specific persons from a defined population.(4) "State and federal public health agencies maintain records of incidences of certain injuries, diseases, and disabilities, as well as actions taken to prevent illness (e.g., immunizations). According to the Centers for Disease Control and Prevention (CDC), "immunization registries are confidential, population-based, computerized information systems that attempt to collect vaccination data about all children within a geographic area."(5) Other types of registries include those for cancer, spinal cord injuries, blood lead, organ donor, and birth defects.

Screening data are a core component of public health information because they reflect interventions by health care professionals before precursor signs of disease are detectable.(6) For instance, newborn screening programs analyze the blood of all newborn children to identify any medical problems that may exist.

Photo: various medical staff doing paperwork

Clinical and laboratory data are found on a patient’s medical record. Healthcare professionals generate this information as a direct result of interaction with the patient, or with individuals who have personal knowledge of the patient, or with both. Clinical data include patient demographics, health history, details of present illness or injury, orders for care and treatment, observations, test results, records of medication administration, diagnoses/problems, allergies, and other healthcare information. Laboratory data include information gathered from laboratory services such as health and environmental assessment, surveillance, quality assurance, training, and consultation. Laboratory data also include information from a core set of tests in pathology, hematology, chemistry, microbiology, and environmental science. Patient Medical Record Information (PMRI) facilitates the creation of a lifetime health record for individuals. PMRI of many individuals may be aggregated to provide the basis for continuous quality improvement, outcomes analysis, and population-based care management. In addition, clinical data can be used with other data sources to determine incidence and prevalence of disease.

"Surveillance is a continuous and systematic process of collection, analysis, interpretation, and dissemination of descriptive information for monitoring health problems.(7) "Surveillance data systems, e.g., systems for infectious diseases, store information on exposure or trends in adverse health effects over a specified period of time that can be used by public health officials for planning, evaluation, or implementation of public health interventions."(8)

In order to better assess the health of the population, surveys are conducted at the state and federal level on general or specific health indicators. Population health surveys are not collected for specific program purpose but rather provide an information base for multiple public health programs. Examples of population health surveys are located below in Exhibit 2.

Population Healthy Survey	Survey Description
Current Population Survey	The U.S. Census Bureau collects monthly information about the population of the United States through CPS. Every March, the CPS focuses on health related information, including whether individuals have health insurance.(9)
Behavioral Risk Factor Surveillance System	The states, in collaboration with CDC, conduct the Behavioral Risk Factor Surveillance System (BRFSS) survey annually to track health risks, such as excessive drinking, overeating, and smoking. "The objective of the BRFSS is to collect uniform, state specific data on preventive health practices and risk behaviors that are linked to chronic diseases, injuries, and preventable infectious diseases in the adult population."(10)
National Hospital Discharge Survey	The National Center for Health Statistics (NCHS) conducts the National Hospital Discharge Survey (NHDS), which is one of a suite of health care surveys. The NHDS has been conducted continuously by the Centers for Disease Control's NCHS since 1965. National estimates of hospital use derived from the NHDS are published for each calendar year by NCHS.(11)
National Health Interview Survey	"The National Health Interview Survey (NHIS) is the principal source of information on the health of the civilian noninstitutionalized population of the United States and is one of the major data collection programs of the National Center for Health Statistics (NCHS). The main objective of the NHIS is to monitor the health of the United States population through the collection and analysis of data on a broad range of health topics" (e.g. monitor trends in illness and disability and to track progress toward achieving national health objectives; epidemiologic and policy analysis of such timely issues as characterizing those with various health problems; determining barriers to accessing and using appropriate health care; and evaluating Federal health programs).(12)
Medical Expenditure Panel Survey (MEPS)	Medical Expenditure Panel Survey (MEPS): The Agency for Healthcare Research and Quality (AHRQ) conducts the Medical Expenditure Panel Survey (MEPS) on the financing and utilization of medical care in the United States. The survey collects data on frequency, cost, and payer type for health services.(13)

Many states conduct disease specific surveys of their populations, focusing on conditions such as diabetes, heart disease, and cancer.

State and local governments are responsible for registering the universe of births, deaths, and marriages in their jurisdictions. Vital records data systems are based on the national vital statistics system, which includes standard certificates and model laws. Birth certificates are completed by hospitals and submitted to health departments. They include public health relevant information on both the mother and the infant. Death certificates are completed by mortuaries and submitted to the health department; underlying and multiple cause-of-death data are provided by physicians. The later are particularly important for assessing the burden of disease and premature mortality at the population level.(14)

Every ten years, the federal government is Constitutionally required to conduct a census of the population. Specifically, this activity is performed by the U.S. Census Bureau, part of the Department of Commerce. In addition to recording the number of individuals in the country, the census also collects numerous amounts of other information, including age, gender, race, ethnicity, housing status, income, etc. These data provide the denominators for population statistics.

The following are links to other sources of information regarding public health data.

(1) Koo, Denise, O’Carroll Patrick, LaVenture Martin (November/December 2001). Public Health 101 for Informaticians. Journal of the American Medical Informatics Association. Vol 8 No 6.
(2) Centers for Disease Control and Prevention, National Center for Health Statistics, Public Health Practice Program Office (October 1999). Public Health Data: Our Silent Partner. Workbook Introduction. pp. 6.
(3) Centers for Disease Control and Prevention, National Center for Health Statistics, Public Health Practice Program Office (October 1999). Public Health Data: Our Silent Partner. Workbook Introduction. pp. 6.
(4) Agency for Toxic Substances and Disease Registry (February 6, 2003). ATSDR Glossary of Terms [On-line], Available: http://www.atsdr.cdc.gov/glossary.html
(5) Centers for Disease Control and Prevention (January 14, 2002). What Are Immunization Registries? [On-line], Available: http://www.cdc.gov/nip/registry/ir.htm
(6) O’Carroll, Patrick W., William Yasnoff, M. Elizabeth Ward, Laura H. Ripp, Ernest L. Martin, eds. (2003). Public Health Informatics and Information Systems. Springer-Verlag. New York, NY.
(7) Rothman, Kenneth J. and Sander Greenland (1998). Modern Epidemiology. pp. 435.
(8) Agency for Toxic Substances and Disease Registry (February 6, 2003). ATSDR Glossary of Terms [On-line], Available: http://www.atsdr.cdc.gov/glossary.html
(9) U.S. Department of Labor, Bureau of Labor Statistics (February 6, 2003). Current Population Survey [On-line], Available: http://www.bls.gov/cps/home.htm
(10) Centers for Disease Control and Prevention (August 30, 2002). 2001 BRFSS Overview [On-line], Available: http://www.cdc.gov/brfss/technical_infodata/surveydata/2001.htm
(11) Centers for Disease Control and Prevention, National Center for Health Statistics (December 14, 2002). National Hospital Discharge Survey: 2000 Annual Summary With Detailed Diagnosis and Procedure Data [On-line], Available: http://www.cdc.gov/nchs/products/pubs/pubd/series/sr13/160-151/sr13_153.htm
(12) Centers for Disease Control and Prevention, National Center for Health Statistics (August 31, 2002). National Health Interview Survey [On-line], Available: http://www.cdc.gov/nchs/about/major/nhis/hisdesc.htm
(13) Agency for Healthcare Research and Quality (October 2002). Overview of the MEPS Web Site [On-line], Available: http://www.ahcpr.gov/data/mepsweb.htm
(14) Australian Institute of Health and Welfare (November 5, 2002). Burden of Disease and Injury in Australia [On-line], Available: http://www.aihw.gov.au/pophealth/burden.html