Performance of herpes simplex challenges in proficiency testing: observations from the College of American Pathologists proficiency testing program

False-positive Papanicolaou (PAP) test rates in the College of American Pathologists PAP education and PAP proficiency test programs: evaluation of false-positive responses of high-grade squamous intraepithelial lesion or cancer to a negative reference diagnosis

CONTEXT

In cytology proficiency testing (PT), participants fail for incorrectly interpreting a high-grade squamous intraepithelial lesion or cancer (HSIL+) Papanicolaou test result as negative. This penalty may lead to a false-positive interpretation of negative slides as HSIL+ to avoid failure.

OBJECTIVE

To investigate factors related to false-positive responses in a PT versus an educational environment.

DESIGN

We analyzed 420,079 responses from 9414 validated negative reference slides in the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytopathology (PAP Education) and compared them with responses from the Gynecologic Cytology Proficiency Testing Program for the percentage of false-positive (HSIL+) interpretations in each of 7 negative subcategories. We evaluated the influence of preparation type (ThinPrep, SurePath, and conventional Papanicolaou test), participant type (pathologist or cytotechnologist), and program time interval (preproficiency test or PT) on a false-positive response.

RESULTS

Reference diagnosis and participant type, but not preparation type, were statistically correlated to false-positive responses. The interaction between program time interval and participant type was also significant. Pathologists had higher rates of false-positive results on preproficiency test (1.2% [800 of 68,690]) than they did on PT (0.8% [993 of 129,857]). Cytotechnologists had no differences between program time intervals (preproficiency, 0.9% [515 of 63,281] versus PT, 1.0 [1231 of 121,621]; P = .91). Negative subcategories frequently mistaken for HSIL+ were reparative changes (4.7% [427 of 9069]), atrophic vaginitis (1.8% [18 of 987]), and negative for intraepithelial lesion or malignancy (1.2% [2143 of 178,651]), but during PT, false-positive rates were significantly increased only for the negative for intraepithelial lesion or malignancy and herpes simplex virus (P < .001).

CONCLUSIONS

Pathologists had lower false-positive rates in the Gynecologic Cytology Proficiency Testing Program than they did in PAP Education, but participants were more likely to report a false-positive response (HSIL+) for negative for intraepithelial lesion or malignancy and herpes simplex virus in the Gynecologic Cytology Proficiency Test Program.

Identification of Trichomonas vaginalis in different Papanicolaou test preparations: trends over time in the College of American Pathologists educational Interlaboratory Comparison Program

CONTEXT

The College of American Pathologists' Interlaboratory Comparison Program in Gynecologic Cytology has seen an increase in enrollment in liquid-based Papanicolaou test challenges with a decrease for conventional Papanicolaou tests. Trichomonas vaginalis can be difficult to identify in all preparation types.

OBJECTIVES

To evaluate 20 years of participant results from the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytology for Trichomonas to ascertain whether performance has changed because of the introduction of liquid-based Papanicolaou and proficiency testing.

DESIGN

Concordance rates for the target diagnosis of Trichomonas vaginalis were evaluated for 167,956 participant responses (1990-2010). A nonlinear mixed model was fit with participant type, preparation type, and a 2-level program year (1990-2005 and 2006-2010) reflecting before and after proficiency testing began. A repeated-measures component allowed modeling of the slide-specific performance to ensure that the overall results were not based on the performance of a few slides.

RESULTS

Cytotechnologists had higher concordance with the target diagnosis than did pathologists (89.8% [72,992 of 81,319] versus 83.4% [72,271 of 86,637], P < .001) and better performance for each preparation type (P = .003). Concordance initially dropped after the introduction of proficiency testing (P < .001) for conventional and liquid-based (SurePath) preparations by both participant types, followed by quick, parallel improvement.

CONCLUSIONS

Performance is high in the detection of Trichomonas vaginalis in the College of American Pathologists Interlaboratory Comparison Program in Gynecologic Cytology. Liquid-based Papanicolaou and proficiency testing minimally affected participant performance. Cytotechnologists performed better over time and across preparation types than did pathologists, although pathologists showed performance results parallel to that of the cytotechnologists. Awareness of the performance differences by pathologists and cytotechnologists, as well as their difference in proficiency among liquid-based techniques, may help ensure accurate results in clinical practice.