Test characteristics of visual inspection with 4% acetic acid (VIA) and Lugol's iodine (VILI) in cervical cancer screening in Kerala, India

Abstract

Simple and inexpensive methods based on visual examination of the cervix are currently being investigated as alternative methods of cervical screening. The test characteristics of visual inspection with 4% acetic acid (VIA), and Lugol's iodine (VILI) and conventional cytology were investigated in a cross-sectional study involving 4,444 women aged 25 to 65 years in Kerala, India. While detection of any acetowhite area constituted a low-threshold positive VIA, detection of well-defined, opaque acetowhite lesions close to or touching the squamocolumnar junction constituted a high-threshold positive VIA test. Detection of definite yellow iodine nonuptake areas in the transformation zone close to or touching the squamocolumnar junction constituted a positive VILI test. Cytology was considered positive if reported as atypia or worse lesions. All screened women were evaluated by colposcopy and biopsies were directed in 1,644 women (37.0%), which allowed the direct estimation of sensitivity, specificity and predictive values. The reference diagnosis was based on a combination of histology and/or colposcopy. True disease status was defined as CIN 2 and worse lesions. A total of 149 (3.4%) women had CIN 2 or worse lesions. The sensitivities of low-threshold VIA, high-threshold VIA, VILI and cytology to detect CIN 2 or worse disease were 88.6%, 82.6%, 87.2% and 81.9%, respectively; the corresponding specificities were 78.0%, 86.5%, 84.7% and 87.8%. Our results indicate that VIA and VILI are suitable alternate screening tests to cytology for detecting cervical neoplasia in low-resource settings.