Example of Differential Misclassification Bias

Pregnancy and Congenital Malformations

Differential Misclassification of Exposure Variables

One of the classic examples of differential misclassification of exposure are studies of exposures during pregnancy and congenital malformations.

• These are commonly done as case-control studies because of the rarity of the outcomes.

Schematic of Differential Misclassification

Differential Sensitivity and Specificity of Exposure Measurement

• with cases less apt to forget things and controls more apt to forget things,
• i.e. differential sensitivity of the exposure measurement.

• The cases may tend to recall things that truly did not happen.

Result: Overestimation