Which of the following is a key disadvantage of case-control studies compared to cohort studies when investigating a disease with a long latency period?

Explanation

## Case-Control Studies and Recall Bias in Long-Latency Diseases **Key Point:** Case-control studies are **retrospective** — they ask participants to recall past exposures. With long latency periods, recall accuracy diminishes, introducing systematic error (recall bias). ### Why Recall Bias is Critical in Long-Latency Diseases 1. **Time elapsed:** Longer the interval between exposure and disease onset, poorer the memory 2. **Differential recall:** Cases may recall exposures more (or less) accurately than controls because they have thought about causation 3. **Telescoping:** Participants may misdate exposures ### Comparison of Cohort vs Case-Control for Long-Latency Diseases | Feature | Cohort Study | Case-Control Study | |---------|--------------|--------------------| | **Direction** | Prospective (exposure → disease) | Retrospective (disease → exposure) | | **Exposure measurement** | Measured at baseline, before disease | Recalled after disease occurs | | **Recall bias risk** | Low (minimal time lag) | **High (long time lag)** | | **Suitable for long latency?** | **Yes** | **No** | | **Cost for rare disease** | High (need large cohort) | Low (select cases efficiently) | **High-Yield:** For diseases with **long latency** (e.g., occupational cancers, chronic degenerative diseases), **cohort studies are preferred** because exposure is measured prospectively before disease develops, avoiding recall bias. **Mnemonic:** **RECALL** = **R**etrospective **E**xposure **C**apture **A**fter **L**ong **L**atency = prone to error. **Clinical Pearl:** Occupational exposure studies (asbestos-mesothelioma, benzene-leukemia) typically use cohort design because workers' exposure records exist and latency is 10–40 years.