Variability of interpretive accuracy among diagnostic mammography facilities.
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.
Jackson
Sara L
SL
Department of Internal Medicine, University of Washington School of Medicine, Box 359854, Seattle, WA 98104, USA. sljack@u.washington.edu
Taplin
Stephen H
SH
Sickles
Edward A
EA
Abraham
Linn
L
Barlow
William E
WE
Carney
Patricia A
PA
Geller
Berta
B
Berns
Eric A
EA
Cutter
Gary R
GR
Elmore
Joann G
JG
D000328:Adult; D000368:Aged; D019540:Area Under Curve; D001706:Biopsy; D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology; D002173:Cancer Care Facilities / Q000458:organization & administration / Q000706:statistics & numerical data*; D002983:Clinical Competence / Q000592:standards; D015986:Confounding Factors, Epidemiologic; D003675:Defensive Medicine; D003937:Diagnosis, Differential; D055088:Early Detection of Cancer; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016365:Liability, Legal; D008318:Malpractice; D008327:Mammography / Q000592:standards / Q000706:statistics & numerical data*; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D015999:Multivariate Analysis; D015588:Observer Variation; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012372:ROC Curve; D011857:Radiographic Image Interpretation, Computer-Assisted; D012680:Sensitivity and Specificity; D014481:United States