HPV test result monitoring of different Bethesda categories in gynaecologic cytology: A valuable quality assurance measure.

BACKGROUND

High-risk human papillomavirus (HPV) test ordering has evolved since the 2006 ASCCP guidelines. In light of the availability of the HPV test results for most women ≥30 y, regardless of the Pap test diagnosis; we examined their value in assessing the overall performance of cytopathologists (CPs).

METHODS

Data were derived for six CPs for Pap test interpretations over 4 y. HPV positivity rates for atypical squamous cells of undetermined significance (ASC-US) and for patients ≥30 y for negative for intraepithelial lesion or malignancy (NILM) and squamous intraepithelial lesion (SIL) (inclusive of low grade SIL (LSIL), high grade SIL (HSIL), and carcinoma) categories were retrieved for individual CPs. ASC/SIL ratios were analysed overall and separately for patient groups <30 y and ≥30 y. Pearson correlation coefficient was calculated to assess correlation between HPV positivity rates for ASC-US, NILM and SIL, and ASC/SIL ratios.

RESULTS

The overall ASC-US HPV positivity rate was 41%-49% for patients <30 y, 32% for patients ≥30 y. Stratifying by patient age group, ASC-US HPV positivity rate, and ASC/SIL ratio showed a negative correlation. Excluding an outlier, the NILM HPV positivity rate and ASC/SIL ratio showed a strong negative correlation.

CONCLUSION

Our study shows that ASC-US HPV positivity rate is dependent on the age of the population that is tested. Monitoring of the HPV positivity rates for NILM and SIL categories can serve as an additional objective measure to assess the performance of CPs. Based on the patient population, the laboratory can establish an initial baseline for these rates and use it to adjust interpretive thresholds in ensuring the diagnostic sensitivity of the test and the quality of the interpretation.