European Journal of Cardiovascular Medicine

Purpose: The purpose of the study was to develop a new scoring system for predicting difficult intubation based on the ratio of the patient’s height to thyromental distance, upper lip bite test(ULBT), head and neck movements, modified Mallampati test(MMT), and neck circumference and compare it with Wilson score. Methodology: This prospective observational study was conducted on 300 ASA I, II, and III patients, who underwent elective surgeries under general anesthesia with endotracheal intubation as per inclusion and exclusion criteria. Results: In this study, among the individual parameters, MMT had the highest sensitivity (61%), while head and neck movements had the highest specificity (95.5%). ULBT had the best positive predictive value (42.9%), negative predictive value (94%), and positive likelihood ratio (5.5). Taking the cutoff for the new score as >=2, it predicted 34 out of 36 difficult intubations. Sensitivity was high at 94.4%. But specificity was low (41.7%). Kappa was 0.13. Wilson score with a cutoff of >=2 predicted only 16 difficult intubations out of 36. Sensitivity was low (44.4%), and specificity was 70.8%. Kappa was 0.09. On comparing the two scores, the sensitivity was very high for the new score >=2 compared with the Wilson score and was statistically significant (94.4% vs. 44.4%, p < 0.01). Specificity was less for the new score than the Wilson score and was statistically significant (41.7% vs. 70.8%, p <0.01). Accuracy was poor for the new score compared to the Wilson score and was significant (48% vs 67.7%, p<0.01).  Positive (PPV) and negative (NPV) predictive values were comparable for both. Using a cut off for New score >=3 resulted in higher sensitivity and specificity (88.9% and 82.6%, respectively) and accuracy of 83.3%. The new score with a cut off of >=3 yielded significantly higher sensitivity (88.9% vs. 44.4%, p <0.01), specificity (82.6% vs 70.8%, p <  0.01), and accuracy (83.3% vs. 67.7%, p <0.01) than Wilson score. PPV (41% vs. 17.2%, p <0.01) and NPV (98.2% vs. 90.3%, p <0.01) were also significantly higher for a new score >=3 than Wilson score. Conclusion: The modified Mallampatti test, the upper lip bite test, the ratio of height to thyromental distance, neck circumference, and, head and neck movements failed to meet the criteria for an ideal predictive test, when used as an independent predictor. When these parameters were combined to derive a new score, the predictive accuracy was much better. We had hypothesized that a new score with a cutoff of >=2 would accurately predict difficult intubation. It was inferior to Wilson score in predicting difficult intubation. By increasing the cutoff to >=3, sensitivity and specificity were equally good, and positive and negative predictive values were also high. On comparing it with the Wilson score, the predictive accuracy of the former was better. A combination of predictors is always better than a single predictor in identifying difficult intubation, and the new score with a cutoff score >=3 predicts difficult intubation better than Wilson score