Real-life effectiveness of screening programs can be very different from the theoretical gains. Nationwide case-control audits with standard SOPs and inclusion of HPV data can be used for repeat evaluations over time, including evaluation of whether implemented improvements work as expected and provide evidence for incremental improvements of programs and prioritization of quality assurance efforts. Whether cases occurred because current guidelines have not been followed, can be studied using a case series approach. But to study the effect of the different elements in the screening process, and whether there is need for new recommendations and guidelines, the analyses needed require linkage to registers and comparison with control subjects from the population and should be performed in a research setting using validated data.
A worked example from the on-going audit conducted by the research arm of the Swedish National Cervical Screening Registry will be presented. Questions addressed by the audit are designed to be relevant and helpful for the responsible actors at the different levels of the screening program. Each aspect of the screening program is examined with data collected in the screening program and healthcare system: optimization of participation, testing quality, screening test methods, triage, referrals, assessment, treatment, and follow up. Issues regarding validity of the data should also be addressed.
The Swedish audit procedures have been developed over two rounds of data collection and analysis. The process requires significant investment but is based on routinely reported data and the analyses have led to concrete results that can be used for programmatic changes. In Sweden, the standardized audit protocol will be repeated regularly to monitor effectiveness of changes, including the upcoming switch to HPV-based primary screening.