Comparison of cytology proficiency testing: glass slides vs. virtual slides.

Objective: To compare proficiency testing in gynecologic cytology using glass slides vs. virtual slides.

Study Design: To compare performance, a sample of 111 individuals (pathologists = 52, cytotechnologists = 59) from participating in-state laboratories were administered 2 proficiency tests. The annual test of the Maryland Cytology Proficiency Testing Program (MCPTP) was administered to individuals in their laboratories following normal work practice (i.e., using microscopes and equipment with which they were familiar). The other test was CytoView II (Centers for Disease Control and Prevention, Atlanta, Georgia, U.S.A.), a computer-based test composed of virtual slides captured from the MCPTP's glass slides, which test administration personnel transported to the individual's laboratory and administered using 1 of 2 laptop computers. ANOVA was used to compare the performance on the 2 tests and the effect of various potential confounding variables. The slides were evaluated by comparing the performance average for each glass slide to that of the matching virtual slides. All data analysis was performed at the 95% confidence interval.

Results: The mean score of the individuals (n = 111) on the MCPTP test was 99.2% (SD = 2.2, range = 90-100%). The mean score of the individuals (n = 111) on CytoView II was 96.8% (SD = 5.8, range = 70-100%). No individual scored < 90% on the glass slide test (pass rate = 100%). Eight individuals (pathologists = 3, cytotechnologists = 5) scored < 90% on the CytoView II (pass rate = 93.8%). Comparison of an individual's performance on the 2 tests demonstrated a significant difference. When virtual slides that did not attain a 90% consensus were excluded from the scoring, a comparison of individual pass rate for the glass slide test (100%) and computer-based test (99.1%) did not demonstrate significant difference.

Conclusion: Each slide (glass or virtual) must be field validated by cytotechnologists and pathologists. If field validation and Clinical Laboratory Improvement Amendment referencing of virtual slides are comparable to those of glass slides, computer-based testing can be equivalent.