This document discusses cross-sectional study designs. It defines cross-sectional studies as a way to collect information about variables and estimate disease prevalence at a specific point in time. The document distinguishes between descriptive cross-sectional studies, which provide information about variables, and analytical cross-sectional studies, which examine relationships between predictors and outcomes. It provides an example of a hypothetical cross-sectional study on smoking and hypertension using a 2x2 table to calculate risk ratios and interpret the results.

1. Cross-Sectional
Studies
Dr. Faiza Abou El-Soud
Professor- Community Health Nursing
Menoufiya University-Egypt

2. ➢Define cross-sectional study design
➢Reason to use cross-sectional study design
➢Different items between cross-sectional and longitudinal study.
➢Discuss types of the cross-sectional studies
➢identify the design of a hypothetical cross-sectional study
➢Identify advantages of cross-sectional study design
➢Discuss disadvantages of cross-sectional study design

3. Classification

6. Definition Reasons to study CS

7. 1-Descriptive Cross- sectional
studies
• Information about /
variables
• Estimate problem- prevalence
• Period prevalence
• Disease & suspected risk
factors population /specfic
individuals
2-Analytical Cross- sectional
studies
• Information - presence
& stength of
• Predictors/ deteminants
of the diseases
• Testing of hypothesis
3-Both

8. I. Descrpitve Cross- sectional studies
Example : Weight of preterm babies in the 1st week in the incubator
Example : Gender (male and female), Smoking condition...

9. II. Analytical Cross- sectional studies
• Information - presence & stength of
• Predictors/ of the diseases.
• Testing of hypothesis :
✓First method
✓Second method

10. hypothetical
There are 2 methods:
First method:
Identification of four subgroups based on presence or absence of and
presence or absence of .

11. hypothetical
Second method:
Two possible approaches to the analysis of results:
(A) the Rate of the Proportion of the Persons with Disease
Calculate the prevalence of
the prevalence of . Or
(B) the Rate of the Proportion of the Persons with Exposure
Calculate the prevalence of
compared to the prevalence of .

12. The Rate ratio is the rate
of the of the
over the
• The Rate ratio
to measure an
of the
disease with exposure

13. Secondmethod:Designofahypotheticalcross-sectionalstudy:A 2 × 2 table of the
findings from the study

14. :

15. :

16. :

17. : Interpretation
the rate ratio of 1.0 indicates equal rates in the
two groups,
the rate ratio greater than 1.0 indicates an
increased risk for the exposed group ,
the rate ratio less than 1.0 indicates a decreased
risk for the exposed group.

18. • Interpretation : People who are exposed to smoking had 6.0 times as
likely to develop hypertension as those who are not
exposed.
• Risk of hypertension among smokers patients = 120/400 = 0.3 = 30%
• Risk of hypertension among non-smokers patients = 30/600 = 0.05= 5%
• Risk ratio = 0.3 ⁄ 0.05 = 6
• The risk ratio is more than 1.0, indicating a incresaed risk or protective
effect for the exposed (smokers) patients. The risk ratio of 6 indicates
that smokers patients were likely (60%, actually) to develop
hypertension compare to nonsmokers patients.
: Interpretation

19. Home Task :
Estimate the Risk Ratio for this example and give your
interpretation?

22. Thank You