Table 6.

Variables that did not achieve 100% with probable cause and possible solution.

Variable	Probable Cause	Solution
Race	Inconsistently captured in EHR	Collect at enrollment
Education	Not well documented in EHR	Re-evaluate value of data/collect at enrollment
Cancer stage	Not entered in EHR	Supplement with manual chart abstraction
HER2/neu; ER/PR status	May not have been evaluated	Better evaluated as widely accepted standard in recent years. Limited testing may be required for older samples.
Contraception	Not well captured in EHR	Collect on enrollment

HER2/neu, Human Epidermal Growth Factor Receptor 2; ER, Estrogen receptor; PR, Progesterone receptor; EHR, Electronic health record