The borderline or weakly positive Hybrid Capture II HPV test: A statistical and comparative (PCR) analysis

Objectives Recent studies have hypothesized that laboratory contamination may influence interpretation of Hybrid Capture II (HCII) human papillomavirus (HPV) detection assay values. Study design To test this hypothesis, 572 consecutive HCII samples were statistically evaluated to test the null hypothesis that cross-well contamination was not present. In addition, 874 consecutive paired samples from patients followed by both HCII and polymerase chain reaction (PCR) analysis were compared. Results A Kendallʹs tau measure of association among adjacent wells yielded a P value of .016, rejecting the null hypothesis of no contamination. Analysis of relative light unit values between 0.8 and 1.5 rejected the null hypothesis at P = .077. Moreover, PCR positivity was significantly higher for samples with HCII values above 1.5 vs 0.8 to 1.5 (P = .001). Conclusion Cross-well contamination of samples occurs during processing, and may influence interpretation of some borderline positives. The proportion of cases at risk is low (<3%). Nevertheless, this information may be germane to the interpretation and reporting of marginally positive HCII test values.