Screening mammograms by community radiologists: variability in false-positive rates.
BACKGROUND
Previous studies have shown that the agreement among radiologists interpreting a test set of mammograms is relatively low. However, data available from real-world settings are sparse. We studied mammographic examination interpretations by radiologists practicing in a community setting and evaluated whether the variability in false-positive rates could be explained by patient, radiologist, and/or testing characteristics.


METHODS
We used medical records on randomly selected women aged 40-69 years who had had at least one screening mammographic examination in a community setting between January 1, 1985, and June 30, 1993. Twenty-four radiologists interpreted 8734 screening mammograms from 2169 women. Hierarchical logistic regression models were used to examine the impact of patient, radiologist, and testing characteristics. All statistical tests were two-sided.


RESULTS
Radiologists varied widely in mammographic examination interpretations, with a mass noted in 0%-7.9%, calcification in 0%-21.3%, and fibrocystic changes in 1.6%-27.8% of mammograms read. False-positive rates ranged from 2.6% to 15.9%. Younger and more recently trained radiologists had higher false-positive rates. Adjustment for patient, radiologist, and testing characteristics narrowed the range of false-positive rates to 3.5%-7.9%. If a woman went to two randomly selected radiologists, her odds, after adjustment, of having a false-positive reading would be 1.5 times greater for the radiologist at higher risk of a false-positive reading, compared with the radiologist at lowest risk (95% highest posterior density interval [similar to a confidence interval] = 1.17 to 2.08).


CONCLUSIONS
Community radiologists varied widely in their false-positive rates in screening mammograms; this variability range was reduced by half, but not eliminated, after statistical adjustment for patient, radiologist, and testing characteristics. These characteristics need to be considered when evaluating false-positive rates in community mammographic examination screening.
Elmore
Joann G
JG
Department of Medicine, University of Washington School of Medicine, Seattle 98104, USA. jelmore@u.washington.edu
Miglioretti
Diana L
DL
Reisch
Lisa M
LM
Barton
Mary B
MB
Kreuter
William
W
Christiansen
Cindy L
CL
Fletcher
Suzanne W
SW
D000328:Adult; D000368:Aged; D001941:Breast Diseases / Q000000981:diagnostic imaging; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D002114:Calcinosis / Q000000981:diagnostic imaging; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D005348:Fibrocystic Breast Disease / Q000000981:diagnostic imaging; D006801:Humans; D008327:Mammography / Q000592:standards*; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D015233:Models, Statistical; D015588:Observer Variation; D016017:Odds Ratio; D011871:Radiology / Q000592:standards*; D015203:Reproducibility of Results