HPValidate - Technical optimisation of self-collected samples for HPV testing within the NHS England cervical screening programme.

The HPValidate study evaluated vaginal HPV self-sampling in the English NHS cervical screening programme. Here we report a secondary objective to examine pre-analytical and analytical technical factors across five workflows, addressing the absence of standardised testing protocols. The workflows included Roche cobas HPV DNA and Hologic APTIMA HPV mRNA assays with Rovers Evalyn® Brush, Copan FLOQSwabs®, and the Hologic Multitest kit. Self-collected samples were compared with clinician-collected samples as the reference standard to establish technical baselines. Outcomes assessed were: (1) sample acceptance; (2) invalid test rates and potential sources of interference (blood, bacterial or fungal growth, participant age, and time from collection to resuspension in 5 ml Hologic ThinPrep® PreservCyt®); and (3) sample stability. Time from self-sample collection to resuspension was identified as a potential determinant of invalid HPV results, with one workflow demonstrating an invalid rate of 5.6% (56/1010) for self-collected samples, compared with no invalid results in matched clinician-collected samples. Following resuspension, samples showed high stability, with reproducibility ranging from (89.4%-100%). These data support the optimisation of laboratory workflows, acceptance criteria, and standardised HPV self-sampling protocols.