Background: Obesity is clinically considered a risk factor for difficult laryngoscopy. This study aimed to evaluate the correlation between Body Mass Index (BMI) and the Cormack and Lehane (C&L) laryngoscopic view in a general surgical population. Methods: A prospective observational study was conducted in 2006 on 1,802 adults undergoing elective surgery requiring tracheal intubation. Patients were categorized by BMI: underweight (<18.5), normal (18.5-24.9), overweight (25-29.9), and obese (≥30). After standardized induction and positioning, the best glottic view on first laryngoscopy was graded (C&L I-IV) by the attending anesthesiologist and recorded by an independent observer. Difficult laryngoscopy was defined as C&L grade III or IV. The correlation between continuous BMI and C&L grade was assessed using Spearman's ρ. The prevalence of difficult laryngoscopy across categories and the diagnostic performance of BMI thresholds were calculated. Results: A weak positive correlation was found between BMI and worse C&L grade (ρ=0.21, p<0.001). The prevalence of difficult laryngoscopy increased across BMI categories: underweight 2.8%, normal 4.4%, overweight 6.5%, obese 13.0% (p for trend <0.001). For predicting difficult laryngoscopy, a BMI ≥30 kg/m² had a sensitivity of 42.5%, specificity of 78.6%, and a positive predictive value of only 13.0%. Conclusion: Increasing BMI is associated with a higher prevalence of difficult laryngoscopy, but the correlation is weak. BMI is a poor standalone predictor due to low sensitivity and very low positive predictive value, emphasizing the need for comprehensive airway assessment beyond weight alone.

Body Mass Index; Obesity; Difficult Laryngoscopy; Cormack and Lehane Grade; Airway Management.