Human papillomavirus load in Hybrid Capture II assay: does increasing the cutoff improve the test?
ABSTRACT The aim of the study was to evaluate whether the results of the Hybrid Capture II (HCII) assay for detecting high-grade squamous intraepithelial lesions (H-SIL) or cervical carcinoma can be improved by increasing the relative light units (RLU) level.
We included 2271 women (mean age 38.7 +/- 12.3, range 15-92) referred to a colposcopic clinic due to cytology of atypical cells of unknown significance, SIL or carcinoma. All women underwent a new Pap test, HR-HPV detection using HCII and colposcopy with biopsy of suspicious areas when present.
HR-HPV was detected in 91.7% of carcinomas, 96.6% of H-SIL, 85.1% of low-grade SIL and 21.6% of cases with no lesion. The probability of harboring an H-SIL or a carcinoma significantly increased as RLU increased (P = 0.01). The sensitivity and specificity for H-SIL or carcinoma at different cutoffs were 95.7 and 54.6 at 1 RLU, 93.9 and 59.6 at 2 RLU, 90.1 and 65.1 at 5 RLU and 85.7 and 68.7 at 10 RLU. The percentage of cases not detected with HCII increased from 2.4% for cases with <1 RLU to 9.5% for cases between 1 and 2 RLU, 14.8% between 2 and 3 RLU, 21.7% between 3 and 5 RLU and 28.4% between 5 and 10 RLU.
The use of a higher cutoff (higher viral load) in the HCII should not be recommended because it significantly increases the number of cases with H-SIL or carcinoma not detected, reducing the sensitivity and negative predictive value of the test.
Article: Cross-sectional comparison of an automated hybrid capture 2 assay and the consensus GP5+/6+ PCR method in a population-based cervical screening program.[show abstract] [hide abstract]
ABSTRACT: In this cross-sectional study, clinical performances of the hybrid capture 2 assay using an automated instrument (i.e., rapid capture system) (hc2-RCS) and the high-risk human papillomavirus GP5+/6+ PCR-enzyme immunoassay (EIA) test were compared using cervical scrape specimens from 8,132 women that participated in a population-based screening trial. The hc2-RCS test scored significantly more samples positive (6.8%) than the GP5+/6+ PCR-EIA (4.8%) (P < 0.0005). This could be attributed largely to a higher positivity rate by the hc2-RCS test for women with cytologically normal, borderline, or mild dyskaryosis. A receiver operator characteristics analysis of the semiquantitative hc2-RCS results in relation to different cytology categories revealed that these differences are owing to differences in assay thresholds. For women classified as having moderate dyskaryosis or worse who also had underlying histologically confirmed cervical intraepithelial neoplasia grade 3 or cervical cancer (> or =CIN3), the hc2-RCS scored 97% (31/32) of samples positive, versus 91% (29/32) by GP5+/6+ PCR-EIA. However, this difference was not significant (P = 0.25). After increasing the hc2-RCS cutoff from 1.0 to 2.0 relative light units/cutoff value of the HPV16 calibrator (RLU/CO), no additional CIN3 lesions were missed by hc2-RCS, but the number of test-positive women with normal, borderline, or mild dyskaryosis was significantly decreased (P < 0.0005). However, at this RLU/CO, the difference in test positivity between hc2-RCS and the GP5+/6+ PCR-EIA was still significant (P = 0.02). The use of an RLU/CO value of 3.0 revealed no significant difference between hc2-RCS and GP5+/6+ PCR-EIA results, and equal numbers of smears classified as > or =CIN3 (i.e., 29/32) were detected by both methods. In summary, both assays perform very well for the detection of >or =CIN3 in a population-based cervical screening setting. However, adjustment of the hc2-RCS threshold to an RLU/CO value of 2.0 or 3.0 seems to produce an improved balance between the clinical sensitivity and specificity for > or =CIN3 in population-based cervical screening.Journal of Clinical Microbiology 10/2006; 44(10):3680-5. · 4.15 Impact Factor