HPV testing of self-collected vaginal swabs may help expand access to cervical cancer screening in low-resource settings. We compared the utility for screening of Xpert HPV when run on self-collected vaginal swabs vs. clinician-collected cervical samples
At a colposcopy and a primary care site in Cape Town, South Africa, 585 HIV-negative aged 30-65 years were recruited. Self-collected vaginal swabs and clinician-collected cervical samples were tested using Xpert HPV. This assay detects high risk HPV in 5 channels: HPV16, HPV18,45, HPV31,33,35,52,58, HPV51,59, HPV39,56,66,68. Outcome of cervical intraepithelial neoplasia grade 2/3 or cancer (CIN2+) was determined by colposcopy and histology for all women.
Sensitivity of Xpert HPV to detect CIN2+ was similar in self- (85.7%) and clinician- (88.3%) collected samples, but specificity was lower in self- (77.0%) vs. clinician- (87.3%) collected samples. Sensitivity could be retained at high levels if screen-positive was defined as positivity for one or more of the three channels detecting HPV 16,18,45,31,33,35,52,58 (84.4% vs 87.0% self vs. clinician, respectively). Restricting to these channels, specificity improved to (82.3 vs 90.5% self- vs. clinician, respectively). Defining screen-positive based on more stringent cycle thresholds (Ct) and allowing sensitivity to be 80%, resulted in specificities of 87.3% and 94.7% in self- vs. clinician-collected samples. If a second clinician-collected sample is obtained and tested from self test-positive women, at 80% sensitivity, specificity can be improved to 92.9%.
HPV testing on self-collected samples has excellent sensitivity. Specificity can be improved by HPV type selection and more stringent Ct cut-offs. Specificity can be improved further with secondary triage with HPV testing on clinician-collected samples.