NEET PG High-Yield: Cohort Studies
A cohort study is an observational, prospective (longitudinal) study design. It follows a group of people (cohort) over time to observe the development of disease based on their exposure status.
Key Metrics
| Metric | Formula | Description |
|---|---|---|
| Relative Risk (RR) |  |
Measure of association: strength of the link. |
| Attributable Risk (AR) | $Latex I_e – I_u$ | Impact of removing the exposure. |
| Population AR | $Latex I_t – I_u$ | Incidence in the total population minus the unexposed. |
High-Yield NEET PG Pearls:
- RR vs. AR: RR measures the strength of association; AR measures public health impact.
- Advantages: Can determine incidence, provides a temporal sequence, and allows study of multiple effects of a single exposure.
- Disadvantages: Expensive, time-consuming, prone to Loss to Follow-up (Attrition Bias); not suitable for rare diseases.
- Famous Examples: Framingham Heart Study (CVD risk factors), British Doctors Study (Smoking/Lung Cancer).