Journal of the National Cancer Institute Advance Access originally published online on May 26, 2009
JNCI Journal of the National Cancer Institute 2009 101(11):814-827; doi:10.1093/jnci/djp105
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© The Author 2009. Published by Oxford University Press.
ARTICLES |
Variability of Interpretive Accuracy Among Diagnostic Mammography Facilities
Affiliations of authors: Department of Internal Medicine, University of Washington School of Medicine, Seattle, WA (SLJ, JGE); Division of Cancer Control and Population Sciences, Applied Research Program, National Cancer Institute, Bethesda, MD (SHT); Department of Radiology, University of California San Francisco Medical Center, San Francisco, CA (EAS); Center for Health Studies, Group Health, Seattle, WA (LA); Cancer Research and Biostatistics, Seattle, WA (WEB); Department of Family Medicine, Oregon Health and Science University, Portland, OR (PAC); College of Medicine, University of Vermont, Burlington, VT (BG); Department of Radiology, University of Colorado Hospital, Denver, CO (EAB); School of Public Health, University of Alabama at Birmingham, Birmingham, AL (GRC)
Correspondence to: Sara L. Jackson, MD, MPH, Department of Internal Medicine, University of Washington School of Medicine, Box 359854, Seattle, WA 98104 (e-mail: sljack{at}u.washington.edu).
Background: Interpretive performance of screening mammography varies substantially by facility, but performance of diagnostic interpretation has not been studied.
Methods: Facilities performing diagnostic mammography within three registries of the Breast Cancer Surveillance Consortium were surveyed about their structure, organization, and interpretive processes. Performance measurements (false-positive rate, sensitivity, and likelihood of cancer among women referred for biopsy [positive predictive value of biopsy recommendation {PPV2}]) from January 1, 1998, through December 31, 2005, were prospectively measured. Logistic regression and receiver operating characteristic (ROC) curve analyses, adjusted for patient and radiologist characteristics, were used to assess the association between facility characteristics and interpretive performance. All statistical tests were two-sided.
Results: Forty-five of the 53 facilities completed a facility survey (85% response rate), and 32 of the 45 facilities performed diagnostic mammography. The analyses included 28 100 diagnostic mammograms performed as an evaluation of a breast problem, and data were available for 118 radiologists who interpreted diagnostic mammograms at the facilities. Performance measurements demonstrated statistically significant interpretive variability among facilities (sensitivity, P = .006; false-positive rate, P < .001; and PPV2, P < .001) in unadjusted analyses. However, after adjustment for patient and radiologist characteristics, only false-positive rate variation remained statistically significant and facility traits associated with performance measures changed (false-positive rate = 6.5%, 95% confidence interval [CI] = 5.5% to 7.4%; sensitivity = 73.5%, 95% CI = 67.1% to 79.9%; and PPV2 = 33.8%, 95% CI = 29.1% to 38.5%). Facilities reporting that concern about malpractice had moderately or greatly increased diagnostic examination recommendations at the facility had a higher false-positive rate (odds ratio [OR] = 1.48, 95% CI = 1.09 to 2.01) and a non–statistically significantly higher sensitivity (OR = 1.74, 95% CI = 0.94 to 3.23). Facilities offering specialized interventional services had a non–statistically significantly higher false-positive rate (OR = 1.97, 95% CI = 0.94 to 4.1). No characteristics were associated with overall accuracy by ROC curve analyses.
Conclusions: Variation in diagnostic mammography interpretation exists across facilities. Failure to adjust for patient characteristics when comparing facility performance could lead to erroneous conclusions. Malpractice concerns are associated with interpretive performance.
| CONTEXT AND CAVEATS Prior knowledge It is known that interpretive performance of mammography screening varies by facility; whether performance of diagnostic interpretation varies by facility has not been investigated. Study design Survey of 45 diagnostic mammography facilities in the Breast Cancer Surveillance Consortium to compare structure, organization, and interpretive processes. Performance measurements were compared and adjusted for patient and radiologist characteristics. Contribution Variations in mammography interpretation occurred across facilities, but after adjustment for patient and radiologist characteristics, only variation in false-positive rates remained. Implications When comparing the performance of mammography interpretation between facilities, patient and radiologist characteristics should be considered. Limitations These results may not be generalizable to other regions of the United States or to other countries where mammography programs, screening guidelines, and systems and requirements for interpretation differ from those of facilities included in this study. From the Editors
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The sponsors had no role in the study design, the data collection and analysis, the interpretation of the results, the preparation of the manuscript, or the decision to submit the manuscript for publication.
We thank the Breast Cancer Surveillance Consortium (BCSC) investigators, participating mammography facilities, radiologists, and women undergoing mammography for the data they have provided for this study. A list of the BCSC investigators and procedures for requesting BCSC data for research purposes are provided at http://breastscreening.cancer.gov/.
Manuscript received October 27, 2008; revised February 27, 2009; accepted March 31, 2009.
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J Natl Cancer Inst 2009 101: 769.