The Papanicolaou (Pap) test—the conventional screening method for cervical intraepithelial neoplasia (CIN)—is suboptimal due to high false-negative and false-positive test results due to the poor quality of sampling, preparation problems and errors in detection and interpretation. In a large number of studies, the diagnostic accuracy of an alternative procedure, liquid-based cytology, has been compared with the Pap test with conflicting results. Few of these studies, however, were randomized and none of the randomized trials were well designed. This cluster randomized controlled trial compared liquid-based cytology and the Pap test with respect to testing positivity rates, histologically confirmed detection rates, and positive predictive values (PPVs). The study subjects were women aged 30 to 60 years who were participants in the Dutch cervical screening program. Between 2004 and 2006, 49,222 patients at 122 practices were screened with liquid-based cytology and 40,562 patients at 124 practices were screened with the Pap test. Screen-positive women were followed prospectively for 18 months after initial screening. All medical personnel and others involved with follow-up of screen-positive women were blinded to the cytology screening system used and initial results. Both the intention-to-treat and per-protocol analysis were used. Multivariate logistic regression analysis was used to adjust for possible confounding factors (age, urbanization level, study site, and period). Detection rate ratios of verified cervical abnormalities were calculated for the liquid-based test relative to the Pap test for the primary histological outcome of CIN grades 1+, 2+, and 3+ and carcinoma. The adjusted positive predictive value (PPV) ratios were also calculated. PPV ratios were evaluated at different levels of test positivity and outcome thresholds. The adjusted detection rate ratio for CIN grade 1+ was 1.01, with a 95% confidence interval [CI] of 0.85–1.19); for CIN grade 2+, the rate ratio was 1.00 (95% CI, 0.84–1.20); for CIN grade 3+, the rate ratio was 1.05 (95% CI, 0.86–1.29); and for carcinoma, the rate was 1.69 (95% CI, 0.96–2.99). Comparable results were found for the PPV ratios. Both the detection rate and PPV ratios were close to one and none of the ratios significantly differed from unity. These findings demonstrate that liquid-based cytology is neither more sensitive nor more specific than the Pap test in detecting CIN or cancer.
No takes yet. Share an insight, caveat, or question.
Siebers et al. (2010) studied this question.