Lectures on Descriptive Epidemiology, Sources of PH Data Flashcards
What is the “nature of data?”
This refers to the source of data (e.g. vital statistics, case registries, physician’s records, general population survey, hospital/clinic cases) and will affect what types of statistical analysis and inferences are possible
What is “representativeness” defined?
External validity; generalizability of findings to the population from which the data have been taken.
What is “thoroughness” defined?
the extent to which all cases of a health phenomenon have been identified.
What is the privacy act of 1974?
Prohibits the release of confidential data without the consent of the individual.
What is the Freedom of Information Act? (1967)
Mandates the release of government information to the public, except for personal and medical files.
What is the Public Health Service Act? (1944)
Protects confidentiality of information collected by some federal agencies, e.g., NCHS.
What is the HIPAA Privacy Act?
Health Insurance Portability and Accountability Act of 1996.
The Secretary of HHS can publicize standards for exchange of health information / research
Individually identifiable information is protected, e.g.
The individual’s physical and mental health
Provision of health care to the individual
Payment for provision of health care
What is data sharing?
Refers to the voluntary release of information by one investigator or institution to another for the purpose of scientific research.
Issue: potential loss of control of information
What is record linkage?
Joining data from two or more sources, e.g., employment records and mortality data.
Applications include genetic research, planning of health services, and chronic disease tracking.
What are some limitations of mortality data?
Exact cause of death may be unclear
Lack of standardization within diagnostic criteria
Stigma with certain diseases may lead to inaccurate reporting
Errors or changes in coding (in accordance with the International Classification of Disease / ICD)
What are limitations of birth data?
Mothers may recall events inaccurately
Some neonatal conditions are not visibly present / noticeable at birth
What are limitations of reportable disease statistics?
Incompleteness of population coverage
Physician failure to complete paperwork
Unwillingness to report stigmatized illnesses
What are multiphasic screening programs?
Ongoing screening programs often are carried out at worksites
Limited by employee turnover
Data may not be etiologic (related to disease)
What is a registry?
a centralized database for collection of data about a disease. E.g. SEER program
Applications: patient tracking, identification of trends in disease, case control studies
How do registries maintain patient confidentiality?
the use of coding algorithms
What is the SEER Program?
The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (NCI) is an authoritative source of information on cancer incidence and survival in the United States.
What are Morbidity Surveys?
collect data on the health status of a population group
Obtain more comprehensive info than routinely collected data
E.g. National Health Survey
What is the National Health Survey?
National Health Survey Act of 1956 established this to obtain information about the health of the US population
Conducted by the NCHS and has three programs
-National Health Interview Survey (& Household Interview Survey)
-Health Examination Survey
-Surveys of health resources
What is the Household Interview Survey?
general household survey
studies comprehensive range of conditions such as diseases, impairments, disabilities, and injuries
What is the Health Examination Survey?
The former name of the Health and Nutrition Examination Survey (NHANES)
What is NHANES?
The National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health and nutritional status of adults and children in the United States. The survey is unique in that it combines interviews and physical examinations. NHANES is a major program of the National Center for Health Statistics (NCHS). NCHS is part of the Centers for Disease Control and Prevention (CDC) and has the responsibility for producing vital and health statistics for the Nation.
The NHANES program began in the early 1960s and has been conducted as a series of surveys focusing on different population groups or health topics. In 1999, the survey became a continuous program that has a changing focus on a variety of health and nutrition measurements to meet emerging needs. The survey examines a nationally representative sample of about 5,000 persons each year. These persons are located in counties across the country, 15 of which are visited each year.
The NHANES interview includes demographic, socioeconomic, dietary, and health-related questions. The examination component consists of medical, dental, and physiological measurements, as well as laboratory tests administered by highly trained medical personnel.
What are sources of insurance data?
Social Security (disability benefits and medicare)
Health Insurance (info on the insured)
Life Insurance (causes of mortality, physical exam results)
Main limitation is that uninsured are excluded
What are deficiencies of hospital data?
not representative of any specific population
different information collected on each patient
settings may differ according to social class (e.g. specialized clinic versus emergency room versus urgent care)
What are the limitations of data from physician’s practices?
Highly limited due to:
confidentiality, highly select group, lack of standardization for information collected
Useful for verification of self reports and sources of expoure data
Is data regarding disease treatment from special clinics/ hospitals helpful?
Yes, but typically only for case control studies of rare diseases
Incidence and prevalence still cannot be determined without denominator info
Patients are highly select so info is not generalizable
What is absenteeism data?
Workplace absenteeism refers to time taken off work due to illness or other reasons, such as child care or transportation issues.
Does not account for persons who do not work or attend school / people who attend ill / people who miss but are not ill
Useful for studying rapidly spreading conditions
What data can we get from school health programs?
Immunizations, physical exams, and self reports of illness
What data can we get from morbidity reports within the armed forces?
Report from physicals, hospitalizations, and selective service examinations
What are the US Bureau of Statistics publications?
Statistical Abstract of the United States
County and City Data Book
Decennial Censuses of Population and Housing
Historical Statistics of the United States, Colonial Time to 1970
What are Metropolitan Statistical Areas (MSAs?)
A geographic entity based on a county or a group of counties with at least one urbanized area with a population of at least 100k (and city with a population of >50k) and adjacent counties with economic ties to the central area.
These provide distinctions between metro and non-metro areas by type of residence, industrial concentration, and population concentration
What are Census Tracts?
small geographic subdivisions of cities, counties, and adjacent areas
Each tract contains about 4000 residents
Designed to create economic uniformity and living conditions
When should intervention occur?
During the incubation period, NOT at the start of symptoms!
What publication has the incubation time for many agents?
Compendium of Microbiology
Are latent period and incubation period typically synonymous?
Yes
Is cancer usually described by incubation period or latent period?
latent period
Who much prevention target?
the population most at risk
Can epidemic and outbreak be interchangeable?
they can be, but are not always
How do we calculate incubation period?
Survey everyone about symptom onset, find the median & mean & outliers
What is another way to name Analytical Epidemiology?
Hypothesis testing
(Observational or Experimental / Intervening)
What is an association?
the relationship between an exposure and an outcome
Positive = as the exposure increases, so do the outcomes
Negative = as the exposure decreases, the outcome increases
(and vice versa)
What are descriptive study examples?
case report
case series
incidence
cross sectional
ecologic
Describe the taxonomy of epidemiological studies
What are the 7 major factors for a study to be meaningful / credible?
- Representativeness
- Power via appropriate sample size
- Comparability
- Time sequence / temporality (causation)
- Good measure of association and interpretation of it
- Generalizability
- Explanation of whether it is Experimental / Interventional, Observational, or Descriptive and why
What is the measure of association for descriptive studies?
Correlation Coefficient
What is an ecological study?
An ecologic study focuses on the comparison of groups, rather than individuals; thus, individual-level data are missing on the joint distribution of variables within groups. Variables in an ecologic analysis may be aggregate measures, environmental measures, or global measures.
the unit of observation is the population or community
What is ecological fallacy?
An ecological fallacy is a logical error that occurs when the characteristics of a group are attributed to an individual.
What ae advantages of ecological studies?
Easy to conduct
Often use existing data
Inexpensive
Provide recommendations for further analysis
Generate or support existing hypothesis
What are disadvantages of ecological studies?
Control / understanding confoundable data is difficult
Coefficients usually cannot be covnerted
Hard to tell if exposure precedes outcome
Difficult to interpret
What ratios are used in different descriptive studies?
Cohort Study: risk ratio
Case Control: odds ratio
Cross Sectional: prevalence ratio or prevalence odds ratio
What are important demographic characteristics in the US population?
Size & size changes
Gender Ratio
Age Structure
Race
Natality (ratio of births to population size)
Life expectancy
Overall Pattern of Mortality
Mortality Rates by Age
What are the reasons for describing disease rates by:
1. person
2. place
3. time
- to assess the health of a population
- to generate hypotheses about causal factors for disease
- to plan and evaluate public health programs
What are reasons to pick an observational versus experimental study design?
Observational:
prevention, treatment, or causal factor
moderate-large effect expected
trial not ethical or feasible or too expensive
Experimental:
prevention or treatment
small effect expected
ethical and feasible
money available
What are reasons to pick a cohort versus case control study design?
Cohort:
little known about exposure
evaluate many effects of exposure
exposure is rare
underlying population is fixed
Case Control:
little known about disease
evaluate many exposures
disease is rare
disease has long induction and latent period
exposure data are expensive
underlying population is dynamic
What are reasons to pick retrospective versus prospective study designs?
Retrospective:
disease has long induction and latent period
Historical exposure
Save time and money
Prospective:
disease has short induction and latent period
current exposure
want high quality data
What do cross sectional studies do?
examine exposure prevalence in relation to disease prevalence in a defined population at a single point in time
What do ecological studies do?
Examine disease rates in relation to a population level factor
Describe the US Age Distribution.
Describe US Racial Distribution
Visual for Case Control Studies
Visual for Cohort Studies
Visual for Experimental Studies
What is the index case?
the first identified case in a group of related cases of a particular communicable or heritable disease.
(may or may not be the same as the primary case)
