vital statistics and secondary data sources

What factors affect the quality of epidemiological data?

• Determined by the sources used to obtain the data and how completely the data cover the reference population

• Affects the permissible applications of the data and the types of statistical analyses that may be performed 

• What is the nature of the data, including sources and content?

• How available are the data?

• What are the appropriate and inappropriate uses of the data?

• How complete is the population coverage?

Definition of external validity.

• Refers to the generalizability of the findings to the population from which the data have been taken. 

• Also known as representativeness

What are considered vital events?

Deaths, births, marriages, divorces, and fetal deaths

What data sources can be used as numerators when calculating prevalence and incidence rates?

• Vital statistics

• Morbidity data

What data sources can be used as denominators when calculating prevalence and incidence rates?

US Census

U.S. Census (who is responsible for collecting the data & what information is collected)

• US Census Bureau

  • Official estimates of  total population size and subdivisions of the population by geographical area

Mortality Data (who is responsible for collecting the data & what information is collected)

National Center for Health Statistics (NCHS) compiles and publishes national mortality rates 

Birth Statistics (who is responsible for collecting the data & what information is collected)

• Collected by state and local vital records offices and info reported to National Vital Statistics System (NVSS), which is overseen by CDC

• Include live births and fetal deaths

• Nearly complete

• Used to calculate birth rates 

• Helpful in understanding birth defects, length of gestation, birth weight, and demographic background of the mother

• Affected by mother’s failure to recall events during pregnancy

• May miss conditions that were not detected at birth

Behavioral Risk Factor Surveillance System (who is responsible for collecting the data & what information is collected)

• Monitor at the state level behavioral risk factors that are associated with chronic diseases

  • Health risk behaviors

  • Preventative health practices

  • Health care access

• Data collected on general health status, health behaviors, preventative behaviors, and risk factors

• Data collected via telephone survey with a fixed core questionnaire and selected modules

• Prevalence data on individuals > 18 years old

National Health and Nutrition Examination Surveys (who is responsible for collecting the data & what information is collected)

• National Center for Health Services responsible

• Data collected via physical exams, lab tests, questionnaires

• Measure of overall health, nutritional status, dental health body measurements, medical history

Cancer registries (who is responsible for collecting the data & what information is collected)

• The National Program of Cancer Registries (NPCR)

• The Surveillance, Epidemiology, and End Results (SEER) Program

  • Network includes invasive cancer cases from 1973

  • Data collection on demographics, diagnosis, histopathology, treatment, and survival

Registry

a centralized database for collection of information about a disease

Register

refers to the document used to collect the information about a disease

What information is included in a death certificate?

• Demographic characteristics (i.e. age)

• Date and place of death (i.e. hospital)

• Cause of death 

  • Immediate cause

  • Contributing factors

Immediate cause of death

final disease or condition resulting in death

Underlying cause

disease or injury that initiated the events resulting in death

Contributing factors

other significant conditions contributing to death

Problems with mortality data

• The specified cause of death may not be entirely accurate 

  • Primary cause of death sometimes unclear

  • Some conditions may be unreported because of stigma

What information is included in birth statistics?

Live births and fetal deaths

Problems with birth data.

• Affected by mother’s failure to recall events during pregnancy

• May miss conditions that were not detected at birth

What is public health surveillance? 

Refers to the systematic and continuous gathering of information about the occurrence of diseases and other health phenomena

Examples of public health surveillance programs.

• Communicable and infectious diseases

  • Sexually transmitted diseases, Rubella, Tetanus, Measles, Foodborne disease, etc

• Non-infectious diseases

  • Asthma, HTN, etc

• Risk factors for chronic disease

How are reportable and notifiable diseases reported in the U.S.? 

Mostly through the CDC

Problems with disease reporting.

• List of diseases reportable varies by state

• Estimated under-reporting from 20-70%, depending on the disease

  • Good quality for rare diseases

    • HIV

    • STIs

  • Poor quality for foodborne illness

  • Requires presentation to the health care system