Comparison of diagnostic efficiency between fluorescence colposcope and conventional colposcopy
The comparison results of colposcopy and pathological examination were illustrated in Table 2. We analyzed the diagnostic efficiency of fluorescence colposcopy on a per-patient basis and per-site basis separately. On the per-patient basis, the ROC curve of each patient’s SBRs was shown in Figure 3A. The set cut-off value was 2.34, correspondingly, there were 10, 32, 50, and 5 patients with true positive (TP), false positive (FP), true negative (TN), and false negative (FN) respectively (Figure 3B, Table 2). A total of 360 cervical sites were sampled in the 97 patients of fluorescence colposcope group. The ROC curve of SBRs on the per cervical site basis was displayed in Figure 3C and the cut-off value was 1.63. The cervical sites of TP, FP, TN, and FN were 16, 87, 250, 7 respectively (Figure 3D, Table 2). For conventional colposcope, comparing the colposcopic impressions with the pathological results, the number of TP, FP, TN, and FN cases were 13, 29, 45, 11 respectively (Table 2).
The diagnostic efficiency including accuracy, sensitivity, specificity, PPV, NPV and associated 95% CI were calculated and shown in Table 3. The diagnostic efficiency of fluorescence colposcope on a per-patient basis (accuracy=61.9%, sensitivity=66.7%, specificity=61.0%, PPV=23.8%, NPV=90.9%) was similar to the conventional colposcope group (accuracy=59.2%, sensitivity=54.2%, specificity=60.8%, PPV=31.0%, NPV=80.4%). However, when performing statistical analysis on a per-site basis, the accuracy, specificity, and NPV of the fluorescence colposcopy group (73.9%, 74.2%, 97.3% respectively) were better than those of the conventional colposcopy group (p=0.005, 0.021, 0.000 respectively), but the PPV (15.5%) was lower (p=0.035). These results indicated that fluorescence colposcope had a comparable effect in diagnosing cervical precancerous lesions compared with conventional colposcope. Surprisingly, this fluorescence colposcope also demonstrated an excellent negative predictive effect, which was valuable for cervical cancer screening.