A systematic review 1 including 9 studies with a total of 6 281 patients was abstracted in DARE. The weighted mean sensitivity and specificity of colposcopy in identifying normal from abnormal tissue was 0.96 and 0.48, respectively. The positive and negative predictive values were 0.82 and 0.79. Likelihood ratios for "negative" test findings or findings of atypia ranged from 0.002 to 0.38, for low-grade SIL 0.38 to 1.19, and for high grade SIL or cancer from 2.49 to 18.7.
A clinical trial 2 evaluated the accuracy of colposcopy. 1 850 women were recruited into a diagnostic or a screening group depending on their history of abnormal findings on Papanicolaou tests. Colposcopy were performed and biopsies specimens obtained from abnormal and normal colposcopic sites for all patients. The golden standard of test accuracy was the histologic report of biopsies. The prevalence of high-grade squamous intraepithelial lesions (HSIL) or cancer was 29.0% for the diagnostic group and 2.2% for the screening group. Using a disease threshold of HSIL, colposcopy had a sensitivity of 0.983 and a specificity of 0.451 in the diagnostic group when the test threshold was low-grade squamous intraepithelial lesions (LSIL), and a sensitivity of 0.714 and a specificity of 0.813 when the test threshold was HSIL. The colposcopy area under the receiver operating characteristic curve was 0.821 (95% CI 0.79-0.85) in the diagnostic setting compared with 0.587 (95% CI 0.56-0.62) in the screening setting. Changing the disease threshold to LSIL demonstrated similar patterns in the tradeoff of sensitivity and specificity and measure of accuracy.
Comment: The quality of evidence is downgraded by limitations in review methdology but upgraded by large magnitude of effect.
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