24-25 Cross Sectional Studies

Question 1

Describe cross sectional studies.

Answer 1

observational, descriptive/analytical studies that examine relationships of health/disease to other variables of interest at the same time

studies all of persons with the variables of interest

defines the geographical boundary for the study

studies disease and risk factor patterns over a specified time period

Question 2

What is another name for cross sectional studies?

Answer 2

Prevalence studies

Question 3

Why is it called a cross sectional study?

Answer 3

because information gathered represents what is occurring at a point in time or time-frame a-cross a large population

Question 4

Is a cross sectional study data a snap shot or continuous?

Answer 4

snap shot

Question 5

What does cross sectional studies focus on?

Answer 5

simultaneously focuses on disease and population characteristics, including exposures, health status, health-care utilization, etc. depending on study purpose

Question 6

What functions do cross sectional studies do?

Answer 6

seeks association
generates and tests hypotheses
by repetition in different time periods, can be used to measure change/trends

Question 7

True or False, most cross sectional studies are surveys of or databases related to different aspects of US population.

Answer 7

True

Question 8

What are the advantages of cross sectional studies?

Answer 8

fairly quick and easy to perform for the researcher using the data
- data already collected and deidentified

Question 9

What are cross sectional studies useful for?

Answer 9

determining prevalence of disease and risk factors across the population (or a sample of them)

measuring current health status and planning for health services across the population (or a sample of them)

evaluating differences in sub-groups within the population (at a given time)

Question 10

What are the disadvantages of cross sectional studies?

Answer 10

prevalent cases may represent survivors
- may be biased in representing people still alive

difficult to study disease of low frequency
- snap shot may not have collected it

problems in determining temporal relationship of a presumed cause and effect
- no temporality you can build; don’t know which came first chicken or egg;

Question 11

List the 2 cross sectional approaches.

Answer 11

1. collect data on each member of the population

2. take a sample of the population and draw inferences to the remainder

Question 12

When is the first cross sectional approach mostly utilized?

Answer 12

city/state level evaluation

Question 13

When is the second cross sectional approach mostly utilized?

Answer 13

US (national) level

Question 14

Describe probability samples of cross sectional sampling schemes.

Answer 14

every element in the population has a known probability of being included in sample

Question 15

True or false, probability samples are NOT the most common type of sampling scheme.

Answer 15

False, it IS the most common

Question 16

When are probability samples most even?

Answer 16

when you use a multi-probability, multi-stage selection

Question 17

List and describe the types of probability samples of cross sectional sampling schemes.

Answer 17

Simple random

 - obtain a list of population names
 - assign numbers to names and use random number generator to select samples

Stratified random

- mutually exclusive strata  - age or socioeconomic groups
- divide population into relevant subgroups
         - take simple random sample from each subgroup
- some studies over sample certain subgroups such as minorities

Question 18

List 2 categories of sampling schemes of cross sectional studies.

Answer 18

Probability samples and Systematic (Convienence) samples

Question 19

Describe systematic samples of cross sectional sampling schemes.

Answer 19

decide on what fraction of population is to be sampled and how they will be sampled

Question 20

List and describe the 2 approaches to collection of new information in cross sectional studies.

Answer 20

Questionnaire/Surveys
- either directly from patients /caregivers or their medical records

Physical assessments
- great for assessing health/disease in similar population as time changes

Question 21

From what perspective does NHANES collection data/information?

Answer 21

Assess the health and nutritional status of adults and children

- Combines interviews and physical examinations
- interviews include demographic, socioeconomic, dietary, and health-related questions

Survey sample is selected to represent the US population of all ages
- over sample persons greater or equal to 60 years old, Blacks/African Americans and Hispanics

Question 22

From what perspective does NHIS collection data/information?

Answer 22

Principle source of information on health of the civilian, non-instutionalized population

- survey sample is selected to represent the US population of all ages
- has central role in other surveys such as the National survey of Family Growth (NSFG) and the NAMCS/NHCS

Question 23

From what perspective does NAMCS collection data/information?

Answer 23

A national survey designed to meet the need for objective, reliable information about the provision and use of ambulatory medical care services in the US

Based on a sample of visits to non-federal, office-based physicians primarily engaged in direct patient care

Question 24

From what perspective does NHCS collection data/information?

Answer 24

A combined national survey designed to describe national patterns of healthcare delivery in non-federal hospitals-based settings, including:
- discharges from inpatient departments and institutions, and visits to ER, outpatient departments, and ambulatory surgery centers

integrates 3 cross-sectional surveys:

- National Hospital Discharge Survey (NHDS)
- National Hospital Ambulatory Medical Care Survey (NHAMCS)
 - Drug-Abuse Warning Network (DAWN)

Question 25

From what perspective does BRFSS collection data/information?

Answer 25

A state-based system of telephone health surveys that collects information on health risk behaviors, preventative health practices, and health care access primarily related to chronic disease and injury

- monthly data collection in all 50 states, DC, Puerto Rico, US Virgin Islands, and Guam
- > 500,000 adults (equal or older than 18) are interviewed by telephone
- Youth BRFSS conducted by questionnaire in schools