Women's anxieties caused by false positives in mammography screening: a contingent valuation survey.

BACKGROUND

Breast cancer screening with mammography has been shown to be effective for preventing breast cancer death. However, mammography screening can be harmful to women. One of the major problems is anxiety from a false positive result. Previous studies do not consider intangible benefits related to anxiety or peace of mind in mammography screening. In order to quantify anxiety, we employed the contingent valuation method (CVM) to measure the general public's willingness to pay (WTP) for mammography screening.

METHODS

About 397 women aged 50-59 participated in the computer-assisted questionnaire survey. For the WTP question format, the double-bound dichotomous choice approach was employed. Participants were randomly assigned into 2 groups. Group A (n = 200) was provided with information about the procedure, detection rate and mortality reduction of mammography screening. Group B (n = 197) was provided with additional information including possibility of false positives and the risks of close examinations.

RESULTS

The mean WTP was significantly greater in Group A than in Group B ($16.82 vs. $12.89, P = 0.02). A Weibull regression analysis showed that, type of information, history of receiving mammography screening, family history of cancer, and the degree of concern about health were significant factors affecting WTP.

CONCLUSIONS

Women must be well informed before making decisions about mammography screening. Although anxiety from information about false positives significantly decreased the women's benefit, the amount of WTP in the well-informed group was still considerable. The results suggest that women can balance the anxiety against the effectiveness.