Standardized abnormal interpretation and cancer detection ratios to assess reading volume and reader performance in a breast screening program.
OBJECTIVE
To determine the relationship between annual screening volume and radiologist performance in the Screening Mammography Program of British Columbia, Canada.


METHODS
Standardized abnormal interpretation ratios and standardized cancer detection ratios were constructed for 35 readers with at least 3 years of experience with the Screening Mammography Program of British Columbia. The ratios were used to compare individual reader performance with the mean program performance after adjustment for the age and screening history (first versus subsequent screening examinations) of the women who underwent screening.


RESULTS
The mean standardized abnormal interpretation ratio was better for readers of 2,000-2,999 (n = 8) and 3,000-3,999 (n = 9) screening mammograms per year than for those of less than 2,000 (n = 9) and 4, 000-5,199 (n = 9) screening mammograms per year. Differences in the mean standardized abnormal interpretation ratios were significant (P <.05) between the readers of less than 2,000 and of 2,000-2,999 screening mammograms per year, between readers of less than 2,000 and of 3,000-3,999 screening mammograms per year and between readers of 3,000-3,999 and of 4,000-5,199 screening mammograms per year. The mean standardized cancer detection ratio improved gradually with increasing annual volume, but the differences between groups were not statistically significant. Five of the eight readers of 2,000-2, 999 mammograms were reading 2,475 or more screening mammograms per year.


CONCLUSIONS
Standardized abnormal interpretation ratios and standardized cancer detection ratios provide a method of comparing two important performance measures in a screening program. A minimum of 2,500 interpretations per year is associated with lower abnormal interpretation rates and average or better cancer detection rates.
Kan
L
L
Screening Mammography Program of British Columbia, 8th Fl, 686 W Broadway, Vancouver, British Columbia, Canada V5Z 1G1.
Olivotto
I A
IA
Warren Burhenne
L J
LJ
Sickles
E A
EA
Coldman
A J
AJ
D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D001943:Breast Neoplasms / Q000000981:diagnostic imaging*; D001955:British Columbia; D002983:Clinical Competence / Q000592:standards*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008327:Mammography / Q000592:standards* / Q000706:statistics & numerical data; D008403:Mass Screening / Q000592:standards* / Q000706:statistics & numerical data; D008499:Medical Records; D008875:Middle Aged; D011785:Quality Assurance, Health Care; D011871:Radiology / Q000592:standards* / Q000706:statistics & numerical data