Subjective but not objective numeracy influences willingness to pay for BRCA1/2 genetic testing

A positive test result for BRCA1/2 gene mutation is a substantial risk factor for breast and ovarian cancer. However, testing is not always covered by insurance, even for high risk women. Variables affecting willingness to pay (WTP) have implications for clinic-based and direct-to-consumer testing. The relative impact of objective and subjective numeracy on WTP, in the context of worry, perceived risk (of having the mutation and developing breast cancer) and family history, was examined in 299 high-risk women, not previously tested for BRCA1/2. Objective and subjective numeracy correlated positively with one another, yet only subjective numeracy correlated (positively) with WTP. This could not be explained by educational level or worry. In line with the numeracy result, other objective factors including family history, age, and Ashkenazi descent were not correlated with WTP. Perceived risk of having a mutation was also correlated with WTP, though perceived risk of developing breast cancer was not, perhaps because it lacks direct connection with testing. Thus, subjective confidence in the ability to interpret test results and perceived risk of a positive test result are more important drivers in paying for BRCA1/2 testing than factors more objective and/or further removed from the testing itself (e.g., perceived risk of developing cancer, family history). Findings underscore the need for genetic counselling that makes probabilistic information accessible and intelligible, so as to build confidence and promote accurate perception of mutation risk and ultimately better decision-making.