Laboratory audit as part of the quality assessment of a primary HPV-screening program

• Primary cervical screening with HPV is today a recommended public health policy.
• Quality control (QC) strategies for routine HPV testing are not well developed.
• The same audit strategy as used for cytology can also be used for HPV testing.
• Routine annual audit is proposed to be part of QC for HPV screening laboratories.
• Higher sensitivity for HPV than for cytology is proposed as audit target.

BackgroundAs primary HPV screening programs are rolled out, methods are needed for routine quality assurance of HPV laboratory analyzes.ObjectiveTo explore the use of similar design for audit as currently used in cytology-based screening, to estimate the clinical sensitivity to identify women at risk for CIN 3 or worse (CIN3+).Study designPopulation-based cohort study conducted within the cervical screening program in Stockholm, Sweden, in 2011–2012. All women with histopathologically confirmed CIN3+ in the following two years were identified by registry analysis. Primary HPV and cytology screening results were collected. For women who had not been HPV tested, biobanked cytology samples were HPV-tested. If the original HPV result had been negative, the sample and subsequent biopsies were analyzed with broad HPV typing (general primer PCR and Luminex).Results154 women had a biobanked prediagnostic cytology sample taken up to 2 years before a histopathologically confirmed CIN3+. The high-risk HPV-positivity was 97% (148/154 women), whereas 143/154 (94%) women had had a cytological abnormality. Among the six HPV-negative samples, one sample was HPV 33 positive in repeat testing whereas the other five cases were HPV-negative also on repeat testing, but HPV-positive in the subsequent tumor tissue.ConclusionsA sensitivity of the HPV test that is higher than the sensitivity of cytology suggests adequate quality of the testing. Regular audits of clinical sensitivity, similar to those of cytology-based screening, should be used also in HPV-based screening programs, in order to continuously monitor the performance of the analyzes.