HS300: Cross-sectional study design

Cross-sectional study

• A type of prevalence study.

• Single period of observation.

• Exposure and disease histories collected simultaneously

• Generally descriptive in nature

• Prevalence data

• Provides quantitative estimates of the magnitude of a
  problem

• Do not measure the temporal order of cause and effect

Measure

• More commonly relate:

  • current disease to current exposure

  • Ex. reduce temperature of the room and see response

• May also

  • current disease to past exposure

  • Ex. walking into room from COLD outside then seeing response

4 steps in cross sectional study

1. Develop what it is you wish to measure (disease, exposure, group affected)

2. Determine target population and select sample (probability sample)

3. Appropriate measure (level) of exposure and outcome

4. Data collected, analyzed to determine measure of association.

Cross-sectional study: examples

• Surveys of smokeless tobacco use among high school students.

• Binge drinking and class attendance rates among BU college students…How?…

Uses/strengths of cross-sectional studies

1. Quick, cheap, no follow up

2. Estimation of the magnitude and distribution of a health problem

3. General population studies (national health interview survey) – results generalizable to general population.

4. Intervention planning (planning health services)

5. May generate etiologic hypotheses

Limitations/weaknesses of cross-sectional studies

1. Not useful for low prevalence diseases. Why?..

2. Cannot study disease etiology (causes) – Why?..

• Prevalence data not incidence data

• Cannot determine temporality of exposure and disease (measure exposure and disease simultaneously) can’t confirm cause and effect relationship

3. Survivors

• Difficult to sort out factors associated with risk and factors associated with survival