Recall rate and sensitivity for screening mammograms increased, whereas specificity decreased from 1996 to 2004 among women with a prior mammogram, and this trend remained after accounting for risk factors, according to a study published online May 26 in Radiology.
Lead author Laura E. Ichikawa, MS, from the Group Health Research Institute in Seattle, and colleagues sought to examine time trends in radiologists’ interpretive performance at screening mammography. They collected subsequent screening mammograms obtained from 1996 to 2004 in women age 40–79 who were followed up for one year for breast cancer.
The researchers included data on about 2.54 million subsequent screening mammograms and 12,498 cancers diagnosed in the follow-up period were included in this study. They found that the recall rate increased from 6.7 percent to 8.6 percent, sensitivity increased from 71.4 percent to 83.8 percent and specificity decreased from 93.6 percent to 91.7 percent.
In generalized estimating equation models, the authors' adjusted odds ratios per calendar year were 1.04 for recall rate, 1.09 for sensitivity and 0.96 for specificity. Random-effects model results were similar. The area under the receiver operating characteristic curve increased over time: 0.869 for 1996–1998; 0.884 for 1999–2001; and 0.891 for 2002–2004. Tumor histologic findings and size remained constant.
Ichikawa and her colleagues concluded the net effect was an improvement in overall discrimination, a measure of the probability that a mammogram with cancer in the follow-up period has a higher Breast Imaging Reporting and Data System assessment category than does a mammogram without cancer in the follow-up period.
Based on their analysis, the researchers noted that the "trends over time do not appear to be caused by changes in patient-visit covariates or in individual radiologist’s performance."
They also noted that the main strength of the study is the large sample of both women and radiologists that is representative of community practice in the U.S.
“Future work is needed to examine other factors that may explain these time trends, including facility and radiologists’ characteristics, technical aspects of mammography and new technologies and their effect on current mammographic practice,” the authors surmised.