Free
Correspondence  |   October 2009
Body Mass Index: An Illogical Correlate of Obesity
Author Affiliations & Notes
  • Lars Hyldborg Lundstrøm, M.D.
    *
  • *Herlev Hospital, Copenhagen University, Herlev, Denmark. (Lundstrøm, Møller, Wetterslev)
Article Information
Correspondence
Correspondence   |   October 2009
Body Mass Index: An Illogical Correlate of Obesity
Anesthesiology 10 2009, Vol.111, 921. doi:10.1097/ALN.0b013e3181b56cb8
Anesthesiology 10 2009, Vol.111, 921. doi:10.1097/ALN.0b013e3181b56cb8
In Reply:—
We will like to thank Woehlck et al.  for their interesting and relevant comments on our assessment of the association between body mass index and a difficult tracheal intubation (DTI).1 We consider the ponderal index (PI) as an operational measurement for obesity, which may be usable in a clinical context as a possible bedside test for predicting a DTI. We performed a preliminary multivariate regression analysis to determine if it is possible to include both body mass index and PI in the same model. This analysis left PI as the only independent significant risk factor for DTI, suggesting that PI may be a better predictor of DTI than body mass index. Nevertheless, the association between PI and DTI was only marginal stronger than between body mass index and DTI. We report this preliminary result with certain reservations, as it may depend heavily on the stratification of the PI,2,3 which is by no means straightforward, as the cutoff value is not naturally given. Furthermore, our preliminary analysis suggests only marginal benefits as to the prognostic accuracy, with PI dichotomized at 25. To determine if a more clinically relevant and statistically significant relationship between the PI and DTI exists, more comprehensive and profound analyses with relevant model control are necessary. Therefore, based on our cohort, we may be able to present a more thorough assessment of this topic in the future.
*Herlev Hospital, Copenhagen University, Herlev, Denmark.
References
Lundstrøm LH, Møller AM, Rosenstock C, Astrup G, Wetterslev J: 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. Anesthesiology 2009; 110:266–74Lundstrøm, LH Møller, AM Rosenstock, C Astrup, G Wetterslev, J
Altman DG, Royston P: The cost of dichotomising continuous variables. BMJ 2006; 332:1080Altman, DG Royston, P
Royston P, Altman DG, Sauerbrei W: Dichotomizing continuous predictors in multiple regression: A bad idea. Stat Med 2006; 25:127–41Royston, P Altman, DG Sauerbrei, W