Strengths and Disadvantages of Cohort Studies

Prospective Cohort Studies

Strengths of Prospective Cohort Studies
  1. They can provide better quality of data on the primary exposure and also on confounding variables
  2. Since exposures are assessed before outcomes occur, they are less prone to bias.


Disadvantages to Prospective Cohort Studies
  1. They are more expensive and time consuming.
  2. They are not efficient for diseases with long latency.
  3. Losses to follow up can bias the measure of association.


Retrospective Cohort Studies

Strengths of Retrospective Cohort Studies
  1. They are useful for rare exposures, e.g., unusual occupational exposures
  2. They are cheaper and faster than prospective cohort studies
  3. They are more efficient for diseases with a long latency period



Limitations of Retrospective Cohort Studies
  1. Exposure data may be inadequate and there may be inadequate data on confounding factors, such as smoking, alcohol consumption, exercise, other health problems, etc.; old records were not designed to be used for future studies


Test Yourself


A study of the association between pesticide exposure and risk of non-Hodgkin lymphoma began in 2011. The incidence of non-Hodgkin's lymphoma was compared in men who worked as pesticide applicators in the 1970s-1980s and men who worked as fertilizer applicators in the 1970s-1980s. Outcome data was collected through 2010.

Is the following statement true or false?

The study described above is a prospective cohort study.