Addressing the Challenge of Assessing Physician-Level Screening Performance: Mammography as an Example

<div><p>Background</p><p>Motivated by the challenges in assessing physician-level cancer screening performance and the negative impact of misclassification, we propose a method (using mammography as an example) that enables confident assertion of adequate or inadequate performance or alternatively recognizes when more data is required.</p><p>Methods</p><p>Using established metrics for mammography screening performance–cancer detection rate (CDR) and recall rate (RR)–and observed benchmarks from the Breast Cancer Surveillance Consortium (BCSC), we calculate the minimum volume required to be 95% confident that a physician is performing at or above benchmark thresholds. We graphically display the minimum observed CDR and RR values required to confidently assert adequate performance over a range of interpretive volumes. We use a prospectively collected database of consecutive mammograms from a clinical screening program outside the BCSC to illustrate how this method classifies individual physician performance as volume accrues.</p><p>Results</p><p>Our analysis reveals that an annual interpretive volume of 2770 screening mammograms, above the United States’ (US) mandatory (480) and average (1777) annual volumes but below England’s mandatory (5000) annual volume is necessary to confidently assert that a physician performed adequately. In our analyzed US practice, a single year of data uniformly allowed confident assertion of adequate performance in terms of RR but not CDR, which required aggregation of data across more than one year.</p><p>Conclusion</p><p>For individual physician quality assessment in cancer screening programs that target low incidence populations, considering imprecision in observed performance metrics due to small numbers of patients with cancer is important.</p></div

Distribution of study population.

<p>*According to Rosenberg, et al. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089418#pone.0089418-Rosenberg1" target="_blank">[19]</a>.</p

Individual physician performance assessment based on volume.

<p>Plots of (A) CDR and (B) RR for the 4 included radiologists at 6 volumes from 500 examinations (then at 1000 and subsequently 1000 exam increments) to the maximum volume read over the 3 years or 5000 total (whichever was least).</p

Defining adequate performance based on volume.

<p>Plots demonstrate our method for constructing curves by using the benchmark threshold as the limit of 95% confidence based on volume: (A) CDR performance levels are established using 2.4 as the lower boundary for 95% CI of adequate performance (CIs shown) and the upper boundary for inadequate performance (CIs not shown). This methodology shows (indicated with a black dot) that a volume of 2770 is required to confidently assert the CDR benchmark median of 4.4/1000 is adequate; (B) RR performance levels are established using 16.8 as the upper boundary for 95% CI of adequate (CI shown) and inadequate (CI not shown) performance. A volume of 120 (indicated with a black dot) is required to confidently assert the RR benchmark median of 9.7% is adequate. Plots define regions of adequate, uncertain, and inadequate performance for (B) CDR and (D) RR.</p

BI-RADS^* final assessment categories with associated recommendation.

<p>*BI-RADS Version 4 <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0089418#pone.0089418-Blanks3" target="_blank">[22]</a>.</p

Annual observed performance values as compared to aggregated data.

<p>Annual CDR for each individual radiologist are shown on this bar graph with performance values and lower bound 95% CI summarized below the bar graph. The fourth bar for each physician represents performance over the 3 years of the study period aggregated (“Agg”) into a consolidated performance metric. Performance values in th first row in italics and bold represent performance values that would be characterized as inadequate using previously published benchmark thresholds.</p