Adjusting mammography--audit recommendations in a lower-incidence Taiwanese population

Medical auditing of screening mammography is crucial to improving the quality of breast cancer care. Audit methodology and recommendations are well documented in the ACR's Breast Imaging Reporting and Data System (BI-RADS). However, when screening a population with a lower incidence rate of breast cancer, performance recommendations should be adjusted for a better fit.

On the basis of known lower breast cancer incidence rates in Taiwan compared with the BI-RADS study populations, the authors investigated a proposed calculation method to adjust the recommendations accordingly. A medical audit of 8,249 consecutive digital mammographic screening examinations was completed. All examinations were done by a hospital-based breast imaging department in Taiwan. Imaging interpretation and medical auditing followed the BI-RADS standards. The results were then compared with those of previous studies as well as the proposed recommendations.

Two of the BI-RADS medical auditing recommendations were adjusted for the Taiwanese population. They were the positive predictive value (PPV) of the initial screening mammographic examination (PPV1) (changed from 5%-10% to 1.7%-3.4%) and cancer detection rate (changed from 2-10 per 1,000 to 0.7-3.4 per 1,000). In the medical auditing results, there were 89 biopsies, with 22 breast malignancies detected. PPV1 was 3.1%, PPV2 was 16.2%, and PPV3 was 24.7%. The cancer detection rate was 2.7 per 1,000 screens, with minimal cancer of 50%, node negative cancer of 71.4%, and a recall rate of 8.5%.

The medical auditing results of this study are consistent with the authors' proposed adjustments to the BI-RADS recommendations for the Taiwanese population. The calculation methods would be generally applicable to other countries or populations to generate their own recommendations for screening mammography.