Self-Sampling Strategy to Encourage Screening for High-Risk Human Papillomavirus

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Women in the self-sampling arm personally collected a vaginal sample and also underwent sample collection by a clinician whereas women in the control arm had both samples taken by a clinician.
Women in the self-sampling arm personally collected a vaginal sample and also underwent sample collection by a clinician whereas women in the control arm had both samples taken by a clinician.

Women who self-screened for high-risk human papillomavirus (hrHPV) had similar test results to those who were screened by a clinician, according to a study published in BMJ.

A research team assessed the accuracy and utilization of self-sampling for hrHPV testing by reviewing 2 meta-analyses that included research published through April 15, 2018.  The first meta-analysis (n=56) included studies that assessed the diagnostic accuracy of self-sample vs clinician sample for hrHPV testing to detect cervical intraepithelial neoplasia grade 2 (CIN2+) or worse (CIN3+) and compared results based on clinical setting, assay, self-sampling device, and storage medium. The second meta-analysis (n=25) included randomized clinical trials that assessed response rates to an offer of self-sampling kits vs a mailed invitation/letter to women who were underscreened.

The accuracy studies were eligible if the following criteria were met: a vaginal sample was collected by the patient herself (self-sample) followed by a cervical sample collected by a clinician (clinician sample); hrHPV assay was performed on both samples; and the presence or absence of CIN2+ was verified by colposcopy or biopsy in all enrolled women or women with 1 or more positive test results. The participation studies were eligible if the following criteria were met: the study population comprised women who were never or irregularly screened; women in the intervention group obtained a self-sample; women in the control group were invited or reminded to undergo clinician sampling; all participation was documented; and at least 400 women were included in the study.

The pooled absolute sensitivity of hrHPV assays for CIN2+ was found to be lower in self-samples (77%; 95% CI, 69%-82%) than in clinician samples (93%; 95% CI, 89%-96%). The pooled absolute sensitivity of hrHPV assays for CIN2+ based on polymerase chain reactions was 96% for both self-samples and clinician samples.  The relative accuracy of hrHPV assays on self-samples vs clinician samples did not vary substantially by clinical setting.  

hrHPV assays based on signal amplification were less sensitive (ratio, 0.85) and less specific (ratio, 0.96) on self-samples vs clinician samples. The test positivity rate was 14% higher and the positive predictive value was significantly lower for both CIN2+ and CIN3+ for self-samples. hrHPV assays based on polymerase chain reaction were equally sensitive (ratio, 0.99 for CIN2+; ratio, 0.98 for CIN3+) but less specific (ratio, 0.98 to exclude CIN2+) on self-samples vs clinician samples.

The percentage of women in the self-sampling arm who completed a self-sampling test when mailed to her home varied between 6.4% and 34.0% (average, 19.2%) in the per-protocol analysis. The pooled percentage of participating women in the intention-to-treat analysis of the self-sampling arm was 17.7% in the opt-in scenario and 94.6% in the door-to-door scenario. The average percentage of women who participated in the control arm was 11.5% in the mail-to-all scenario, 13.4% in the opt-in scenario, 6.0% in the community campaigns scenario, and 53.3% in the door-to-door scenario. Participation was not significantly different when hrHPV testing was performed vs cytology (P =.60 vs P =.76).

The relative participation rate was 1.87-times and 2.33-times higher in the self-sampling arm compared with the control arm of the trials with a mail-to-all scenario, in the per-protocol and intention-to-treat analyses, respectively. For trials with opt-in scenarios, per-protocol analysis revealed a lower participation rate in the self-sampling vs control arm (0.73), whereas in the intention-to-treat analysis, relative participation of the self-sampling arm exceeded the control arm (1.22). Participation rates decreased with increasing length of time since last screening in both arms.

In women with self-samples that tested positive for hrHPV, 80.6% had a follow-up examination. Adherence to follow-up was lower in the self-sampling arm vs in the control arm, but this finding was not statistically significant. The CIN2+ detection rate in the self-sampling arm varied between 0 and 11 per 1000 screened women. On average, the detection rate of CIN2+ was 2.28-times higher in the self-sampling arm vs the control arm. The detection rate ratio varied with a greater detection rate ratio (P =.031) in women with a self-sample that tested positive for hrHPV who were directly referred for colposcopy. The detection rate varied between 0 and 35 per 1000 screened women. The detection rate per number of screened women was similar in the 2 arms (relative proportion, 1.13).

The authors conclude that “hrHPV testing with an appropriate assay offers a promising new strategy that could increase population coverage substantially.”

Reference

Arbyn M, Smith SB, Temin S, Sultana F, Castle P; on behalf of the Collaboration on Self-Sampling and HPV testing. Detecting cervical precancer and reaching underscreened women by using HPV testing on self samples: updated meta-analyses. BMJ. 2018;363:k4823.

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