Testing for HPV as an objective measure for quality assurance in gynecologic cytology: positive rates in equivocal and abnormal specimens and comparison with the ASCUS to SIL ratio.

BACKGROUND Inappropriate use of the category of atypical squamous cells of undetermined significance (ASCUS) can result in overtreatment or undertreatment of patients, which may decrease the cost effectiveness of screening. Quality assurance tools, such as the ASCUS to squamous intraepithelial lesion ratio (ASCUS:SIL) and case review, are imperfect. High-risk HPV (hrHPV) testing is an objective test for a known viral carcinogen, and hrHPV may be more useful in monitoring the quality of ASCUS interpretations. METHODS hrHPV rates for cytologic diagnoses and patient age groups were calculated for a 2-year period. All hrHPV results for ASCUS and SIL over a 17-month period were analyzed by patient age group, over time, and by individual cytopathologist to compare hrHPV rates with the corresponding ASCUS:SIL. RESULTS The hrHPV positive rate for SIL was >90%, and it was 32.6% for ASCUS. Stratification by patient age showed that approximately 50% of patients younger than 30 years and older than 70 years of age were hrHPV positive, whereas other patients had a lower rate ranging from 14% to 34%. The overall ASCUS:SIL was 1.42, and the overall hrHPV positive rate was 39.9%. Over time and by individual cytopathologist, the hrHPV rate performed similarly to the ASCUS:SIL. The analysis by patient age showed a high statistical correlation (R(2) = 0.9772) between the 2 methods. CONCLUSIONS Despite differences between these techniques, the hrHPV rate closely recapitulates the ASCUS:SIL. When used together, the 2 methods can complement each other. The desirable hrHPV-positive range appears to be 40% to 50%; however, this may vary based on the patient population. The hrHPV rate is as quick and cost effective as determining the ASCUS:SIL.