Randomized Comparison of Two Vaginal Self-Sampling Methods for Human Papillomavirus Detection: Dry Swab versus FTA Cartridge

Abstract

BackgroundHuman papillomavirus (HPV) self-sampling (self-HPV) is valuable in cervical cancer screening. HPV testing is usually performed on physician-collected cervical smears stored in liquid-based medium. Dry filters and swabs are an alternative. We evaluated the adequacy of self-HPV using two dry storage and transport devices, the FTA cartridge and swab.MethodsA total of 130 women performed two consecutive self-HPV samples. Randomization determined which of the two tests was performed first: self-HPV using dry swabs (s-DRY) or vaginal specimen collection using a cytobrush applied to an FTA cartridge (s-FTA). After self-HPV, a physician collected a cervical sample using liquid-based medium (Dr-WET). HPV types were identified by real-time PCR. Agreement between collection methods was measured using the kappa statistic.ResultsHPV prevalence for high-risk types was 62.3% (95%CI: 53.7–70.2) detected by s-DRY, 56.2% (95%CI: 47.6–64.4) by Dr-WET, and 54.6% (95%CI: 46.1–62.9) by s-FTA. There was overall agreement of 70.8% between s-FTA and s-DRY samples (kappa = 0.34), and of 82.3% between self-HPV and Dr-WET samples (kappa = 0.56). Detection sensitivities for low-grade squamous intraepithelial lesion or worse (LSIL+) were: 64.0% (95%CI: 44.5–79.8) for s-FTA, 84.6% (95%CI: 66.5–93.9) for s-DRY, and 76.9% (95%CI: 58.0–89.0) for Dr-WET. The preferred self-collection method among patients was s-DRY (40.8% vs. 15.4%). Regarding costs, FTA card was five times more expensive than the swab (~5 US dollars (USD)/per card vs. ~1 USD/per swab).ConclusionSelf-HPV using dry swabs is sensitive for detecting LSIL+ and less expensive than s-FTA.Trial RegistrationInternational Standard Randomized Controlled Trial Number (ISRCTN): 43310942

Accuracy of self-collected vaginal dry swabs using the Xpert human papillomavirus assay

“…Agreement was only fair between the two samples for genotypes 39, 56, 66 and 68. These results are consistent with previous studies comparing dry and wet samples using different HPV DNA tests such as the Roche Linear Array [ 12 ], Seegene Anyplex II HPV28 [ 13 ] and Roche Cobas 4800 test [ 14 ].…”

“…However, for detecting CIN2+, there was a trend towards a better performance with s-DRY as compared to dr-WET or cobas, although these differences did not reach statistical significance. Equivalent and even improved sensitivity of self-HPV was found in previous studies when PCR-based HPV tests were used [ 13 , 15 , 16 ]. Our results are consistent with these studies, with a specificity of s-DRY that is lower than dr-WET samples.…”

Self-Collection for Cervical Screening Programs: From Research to Reality

“…The information seems to suggest that factors other than clinical sensitivity may be the deciding factor for the use of a device within a specific cervical screening program. The cost of self-collection devices can be prohibitive, with the FTA ® -cartridge costing more than US$5 whereas a Copan flocked swab is under US$1 [52]. Environmental stability is also a variable requirement depending on the situation-temperature and humidity vary greatly from region to region.…”

“…Currently the wealth of evidence supports PCR-based assays for use in self-collection protocols, and this is explicitly stated in the Australian technical requirements for HPV-based cervical screening [24]. It should also be noted that most of the currently utilised mediumto high-volume HPV assays test for the same 14 HPV types; 16,18,31,33,35,39,45,51,52,56,58,59, 66, and 68. It is important to note that each different combination of device, buffer and assay/system requires validation, either by the manufacturer or by individual laboratories.…”

“…Although numbers of histologically confirmed CIN2+ were low, there was a tendency for better detection by the flocked sample (9 CIN2+) compared with the cotton swab (5 CIN2+). Another small study [52] used the Copan ESwab™ for self-collection and compared it to a self-collection sample stabilized on an FTA ® -cartridge, and a clinician-collected specimen. The flocked swab had equal or greater sensitivity than both the FTA ® -cartridge and the clinician-collected specimen.…”