title: High body mass index is a weak predictor for difficult and failed tracheal intubation: a cohort study of 91,332 consecutive patients scheduled for direct laryngoscopy registered in the Danish Anesthesia Database.
abstract: BACKGROUND
  Previous studies have failed to detect high body mass index (BMI) as a risk factor for difficult tracheal intubation (DTI). BMI was investigated as a risk factor for DTI in patients planned for direct laryngoscopy.
  
  
  METHODS
  A cohort of 91,332 consecutive patients planned for intubation by direct laryngoscopy was retrieved from the Danish Anesthesia Database. A four-point scale to grade the tracheal intubation was used. Age, sex, American Society of Anesthesiologists physical status classification, priority of surgery, history of previous DTI, modified Mallampati-score, use of neuromuscular blocker, and BMI were retrieved. Logistic regression to assess whether BMI was associated with DTI was performed.
  
  
  RESULTS
  The frequency of DTI was 5.2% (95% confidence interval [CI] 5.0-5.3). In multivariate analyses adjusted for other significant covariates, BMI of 35 or more was a risk for DTI with an odds ratio of 1.34 (95% CI 1.19-1.51, P < 0.0001). As a stand alone test, BMI of 35 or more predicted DTI with a sensitivity of 7.5% (95% CI 7.3-7.7%) and with a predictive value of a positive test of 6.4% (95% CI 6.3-6.6%). BMI as a continuous covariate was a risk for failed intubation with an odds ratio of 1.031 (95% CI 1.002-1.061, P < 0.04).
  
  
  CONCLUSIONS
  High BMI is a weak but statistically significant predictor of difficult and failed intubation and may be more appropriate than weight in multivariate models of prediction of DTI.
authors.affiliation: Department of Anesthesia and Intensive Care Herlev, and Copenhagen Trial Unit, Centre of Clinical Intervention Research, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark. lars_hyldborg@hotmail.com
authors.forename: Lars H
authors.initials: LH
authors.lastname: Lundstrøm
authors.forename: Ann M
authors.initials: AM
authors.lastname: Møller
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rosenstock
authors.forename: Grethe
authors.initials: G
authors.lastname: Astrup
authors.forename: Jørn
authors.initials: J
authors.lastname: Wetterslev
mesh_terms: D000704:Analysis of Variance; D001827:Body Height / Q000502:physiology; D015992:Body Mass Index; D001835:Body Weight / Q000502:physiology; D016208:Databases, Factual; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000453:epidemiology*; D007442:Intubation, Intratracheal / Q000706:statistics & numerical data*; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D019148:Neuromuscular Blockade; D009765:Obesity / Q000150:complications*; D050177:Overweight / Q000150:complications*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D012044:Regression Analysis; D012307:Risk Factors; D018401:Sample Size; D017211:Treatment Failure