Time and temperature dependent analytical stability of dry-collected Evalyn HPV self-sampling brush for cervical cancer screening

Abstract

As a new initiative, HPV self-sampling to non-attenders using the dry Evalyn self-sampling brush is offered in the Capital Region of Denmark. The use of a dry brush is largely uncharted territory in terms of analytical stability. In this study we aim to provide evidence on the analytical quality of dry HPV self-sampling brushes as a function of time and temperature. We assessed the analytical stability of dry stored Evalyn brushes at three different temperatures, (4 °C, room temperature, 30 °C) and five different storage time points; T = 0 (baseline), 2, 4, 8, 16, and 32 weeks prior to HPV analysis using the BD Onclarity HPV assay. Mean Ct value of the Onclarity internal control was used as comparator of cellularity across time and temperatures, with no or only borderline statistical differences observed. HPV detection was stable throughout the five time points. In addition, analytically amplifiable DNA copy numbers and DNA fragmentation was assessed using the Agena iPLEX Exome QC assay, with no or only borderline statistical differences observed. In conclusion, the Evalyn brush is analytically stable with respect to human genomic material and HPV detection for up to 32 weeks at temperatures ranging from 4 °C to 30 °C.

Keywords: Analytical stability; Cervical cancer screening; Dry self-sampling brushes; HPV; Self-sampling.

Fig. 1

: Study Flowchart. ¹ Two samples were excluded due to technical reasons during processing. ² The sample number (n) for each of the temperature study periods is listed in Table 1.

Fig. 2

Stability of dry Self-samples brushes stored at 0–32 weeks for three different temperatures (4 °C, RT, 30 °C), presented as box blot for Ct value of the internal control of BD Onclarity HPV assay.

Fig. 3

: Stability of HPV genotypes on dry self-sampling brushes at storage for 0–8 weeks. The horizontal line indicates the clinical cut-off of 34.2 Ct. Numbers in parentheses indicate number of samples with the stated genotype. One sample had a multiple infection of HPV45 and HPV52, which is why there are 17 infections and 16 samples.

Fig. 4

: Stability of HPV genotypes on dry self-sampling brushes at storage for 0–32 weeks. The horizontal line indicates the clinical cut-point of 34.2 Ct. Numbers in parentheses indicate number of samples with the stated genotype.