PSM Made Easy

Epidemiology: Differences between Case – control and cohort study

Epidemiology

Case – control study

  • Proceeds from the outcome to cause
  • Starts with cases of disease
  • Tests if the suspected risk factor occurs more often in the cases than that in the controls
  • Usually the first study for testing a hypothesis
  • Requires fewer number of participants
  • Yields the results relatively earlier
  • Suitable for rare diseases
  • Cannot directly estimate the relative risk hence calculates the ‘Odd’s ratio’ (OR)
  • Only one outcome (disease) can be studied
  • Inexpensive

Cohort study

  • Proceeds from cause to outcome
  • Starts with people exposed to the risk factor but free from the disease
  • Tests if the disease occurs more frequently among those exposed as compared to those not similarly exposed
  • Conducted for a more established hypothesis
  • Involves larger number of participants
  • Long follow ups lead to delayed results
  • Not suitable for rare diseases
  • Directly estimates the relative risk (RR)
  • More than one outcome can be studied
  • expensive

References:

Tiwari P. Epidemiology Made Easy. New Delhi: Jaypee Brothers; 2003 Gordis, L. (2014). Epidemiology (Fifth edition.). Philadelphia, PA: Elsevier Saunders. Bonita, R., Beaglehole, R., Kjellström, T., & World Health Organization. (2006). Basic epidemiology. Geneva: World Health Organization. Schneider, Dona, Lilienfeld, David E (Eds.), 4th ed. Lilienfeld’s Foundations of Epidemiology. New York: Oxford University Press; 2015 K. Park. Principles of Epidemiology and Epidemiologic Methods. In Park’s Textbook of Preventive and Social Medicine. 24th Ed. Jabalpur: Banarasidas Bhanot, 2017: pg 58 – 145

Steps in Investigation of an Epidemic:

http://www.ihatepsm.com/blog/epidemiology-steps-investigation-epidemic

Tests of Significance

:

http://www.ihatepsm.com/blog/epidemiology-tests-significance

Monitoring and Evaluation

:

http://www.ihatepsm.com/blog/epidemiology-monitoring-and-evaluation

Advantages and Disadvantages of Case Control Studies

:

http://www.ihatepsm.com/blog/epidemiology-advantages-and-disadvantages-c...

Advantages and disadvantages of cohort study

:

http://www.ihatepsm.com/blog/epidemiology-advantages-and-disadvantages-c...

Basic Concepts in Epidemiology:

http://www.ihatepsm.com/blog/epidemiology-basic-concepts

Types of Epidemiological Studies:

http://www.ihatepsm.com/blog/epidemiology-types-epidemiological-studies

Differences between Case – control and cohort study

:

http://www.ihatepsm.com/blog/epidemiology-differences-between-case-%E2%8...

Uses of epidemiology:

http://www.ihatepsm.com/blog/epidemiology-uses-epidemiology

Blinding in Experimental Studies:

http://www.ihatepsm.com/blog/blinding-experimental-studies

Evaluation of a Screening Test

:

http://www.ihatepsm.com/blog/epidemiology-evaluation-screening-test