Module Components

• Learning Activities

Topics

• Critical Appraisal Principles
• Systematic Review Appraisal
• Randomized Control Trial Appraisal
• Cohort Study Appraisal
• Case Control Study Appraisal
• Module 8 Self-Review

NDNP 802-Methods for Evidence-Based Practice

Module 8: Critically Appraising Quantitative Evidence

Case Control Study Appraisal

A case-control study belongs to the observational group of studies. It begins by choosing individuals who have a health outcome or disease whose cause you want to investigate. These are the cases. Controls without the health outcome are then chosen. You then determine the proportion of cases who were exposed to any risk factor of interest in the past, and compare this with the proportion exposed in the control group. The study is generally retrospective because it looks backwards in time to the earlier exposures of individuals.

Advantages

• Good for studying rare conditions or diseases
• Less time needed to conduct the study because the condition or disease has already occurred
• Lets you simultaneously look at multiple risk factors
• Useful as initial studies to establish an association
• Can answer questions that could not be answered through other study designs

Disadvantages

• Retrospective studies have more problems with data quality because they rely on memory and people with a condition will be more motivated to recall risk factors (also called recall bias).
• Not good for evaluating diagnostic tests because it’s already clear that the cases have the condition and the controls do not
• It can be difficult to find a suitable control group

Example

• Chambers, C. D., Hernandez-Diaz, S., Van Marter, L. J., Werler, M. M., Louik, C., & Jones, K. L. et al. (2006). Selective serotonin-reuptake inhibitors and risk of persistent pulmonary hypertension of the newborn. New England Journal of Medicine, 354(6), 579-587.

This study used a matched design, matching infants who had persistent pulmonary hypertension with infants who did not have it, and compared the rates of exposure to SSRIs.

Case Control Study Critical Appraisal Tool - See "Tool" in Lesson Plan under "Recommended Reading"