[355] Hybrid Capture 2 Test Results after an Initial Equivocal RLU/CO Value Are Dependent on Age

Camille T Elkins, Christiaan E de Vries, Julie A Stephens, Adrian A Suarez. The Ohio State University, Columbus, OH

Background: Manufacturer recommended interpretation guidelines for the high risk human papilloma virus (HPV) test Hybrid Capture 2 (HC2) require retesting specimens with an initial equivocal result, defined as a Relative Light Unit/ Cut Off (RLU/CO) value between 1 and <2.5. While a retest with RLU/CO≥1 leads to a “positive” HC2 result, a lower value requires a second retest which is then considered final (“positive” if RLU/CO≥1). However, we have previously documented a low predictive value for cervical intraepithelial neoplasia 2 or worse in women ≥50 years with specimens within the equivocal range and questioned the use of a single interpretative algorithm regardless of age. Therefore, we now decided to investigate the influence of age on HC2 final results produced by the current interpretative algorithm for initial equivocal RLU/CO values.
Design: We identified 365 consecutive cervico-vaginal liquid cytology specimens with initial HC2 HPV tests within the equivocal range. Retest and second retest RLU/CO values were compared for women of three different age groups (15-29, 30-49 and ≥50 years).
Results: The proportion of retests with RLU/CO<1 increased with age (p<0.001 based on Chi-square test).

Retests By Age Group
Age in YearsRLU/CO<1RLU/CO≥1Total
15-2912 (7.4%)151 (92.6%)163
30-4928 (20.1%)111 (79.9%)139
≥5017 (27%)46 (73%)63
Total57308365


59 second retests were performed out of which only 7 had RLU/CO≥1. The proportion of second retests with RLU/CO<1 vs RLU/CO≥1 was not statistically significant (p=0.140). Overall, the proportion of “positive” HC2 results following the current interpretative algorithm decreased with increasing age (p<0.001).
Conclusions: HC2 test results after an initial equivocal RLU/CO value are clearly dependent on age. The likelihood of a retest with RLU/CO≥1 resulting in a “positive” HC2 result decreases significantly with increasing age. These laboratory results appropriately parallel the known HPV infection prevalence in the general population.
Category: Cytopathology

Tuesday, March 20, 2012 9:30 AM

Poster Session III # 40, Tuesday Morning

 

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