What are Case-Control studies

Theoretically, case-control studies are akin to taking a patient case history and doing a physical examination, where facts and findings are amalgamated to find the predisposing factors. ¹ A case-control study is designed to establish if the outcome is a result of exposure. The outcomes may be a disease, condition, complication etc. The methodology includes grouping the population studies into cases – the group with the outcome and controls- without the outcome. Then, retrospectively, the participant’s groups are analysed and compared to gather data about risk factors and exposures frequency. The medical data collection can be done by interview, from case records or by the survey.

Case-control studies are best suited to study outbreaks and rare diseases or outcomes. The advantages are – ideal for examining outcomes with an extended latency period. The result can be obtained fast, inexpensive, engaging pre-existing records, usually needs fewer subjects, and multiple exposures or risk factors can be assessed. The disadvantages are – prone to recall bias, tricky to authenticate completeness and reliability of records, inability to gather incidence data, and choosing a suitable comparison group may pose difficulties.

The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) statement can guide case-control studies.¹

References

1. Song JW, Chung KC. Observational studies: cohort and case-control studies. PlastReconstr Surg. 2010;126(6):2234-2242.

2. Lewallen S, Courtright P. Epidemiology in practice: case-control studies. Community Eye Health. 1998;11(28):57-58.