Visual inspection plus human papillomavirus testing or liquid-based cytology : how best to control cervical cancer in Peru
The main objective of this thesis was to estimate the sensitivity and specificity of four screening tests: visual inspection after the application of acetic acid (VIA), VIA_M: combined VIA and VIAM (magnified VIA using an AviScope performed by a doctor), liquid-based cytology (LBC using the AutoCyte-Prep manual system) and HPV testing (using Hybrid Capture II); to detect histologically confirmed high-grade squamous intra- epithelial lesions (HSIL). Participants of the "Tamizaje y Tratamiento Inmediato de lesiones cervico-uterinas" (TATI) project, who signed an informed consent for additional cervical samples, were included in this study. Separate cervical samples for conventional cytology (CC), LBC and Hybrid Capture II (HC-II), were collected by a midwife before applying acetic acid (5%) to the cervix and performing VIA. Women testing positive on VIA were referred to VIAM performed by a doctor who confirmed the midwife diagnosis, and treated lesions with cryotherapy if appropriate, or referred women to colposcopy. Negative women on VIA_M; underwent colposcopy if they had HSIL on CC or LBC; or had second screening if they had any lesser abnormality on LBC or were positive only on HC-II. Of 5565 participants, 104 had histologically confirmed HSIL and an estimated 112 had undetected/unconfirmed HSIL. Sensitivities of VIA, VIA_M, LBC (any abnormality), LBC (high-grade abnormality) and HC-II were 44% (95% confidence interval (CI): 34,59), 31% (CI: 20,50), 69% (CI: 61,78), 35% (CI: 23,56) and 72% (CI: 65,79), respectively. VIA had the lowest specificity among all tests: 77% (CI: 74,77). LBC ?HSIL had the highest PPV: 44% (CI: 34,53). HC-II was more sensitive than the other tests in our study. LBC ?HSIL was more specific than the other tests. VIA had low sensitivity and specificity. VIA could still be an option for developing countries if implemented with regular quality assurance.