3.3 Establishment of the LFS system based on laryngoscopic characteristics and a comparison with other methods
According to the regression analysis, the effect of hyperemia was the most obvious factor (OR=38.278), followed by the involvement of anterior commissure (OR=5.314) and thick leukoplakia (OR=4.556). We established a vocal cord LFS system with a possible range of 0-10 points (see Table 3 for details). To facilitate calculation and memorization, according to the regression coefficient, four points were assigned to hyperemia, two points to the involvement of anterior commissure and thickness, and one point to two indicators (size and texture) correlated with benign and malignant leukoplakia (Score=4×hyperemia + 2×involvement of anterior commissure + 2×thickness + 1×size + 1×texture). The total scores of the benign vocal cord leukoplakia group and malignant vocal cord leukoplakia group were calculated according to the above scoring system, and the ROC curve was generated. The area under the ROC curve (AUC) for the diagnosis of benign and malignant vocal cord leukoplakia by the scoring system was 0.946 (95% CI: 0.916-0.976, P =0.000). In addition, according to the calculation formula (Score=0.060×age +2.609×texture +1.307×hyperemia) for assessing benign and malignant vocal cord leukoplakia reported by Fang et al .4, the AUC was 0.880 (95% CI: 0.821-0.939, P =0.000); the AUC according to the classification of leukoplakia reported by Zhang et al .5 was 0.742 (95% CI: 0.664-0.820,P =0.000). The AUC of the LFS was significantly better than that of the Fang score (P = 0.0143) and Zhang classification (P<0.0001) (Figure 1).