To the Editor:

I congratulate Glance et al.  1for their work on elucidating the risk profiles of patients with modified metabolic syndrome. Their findings may change the way physician, billing, and insurance groups look at obese patients in the future. For this study, and for the interesting study methods, they must be commended. In addition, the described “complex” of obesity, diabetes mellitus, and hypertension encapsulates metabolic risk features of obstructive sleep apnea. The Perioperative Sleep Apnea Prediction score is a validated screening method that uses all three variables as a clinical prediction tool for sleep apnea.2Thus, the study findings could well be used to describe the perioperative outcomes associated with increased risk of sleep apnea.

One unresolved issue is whether diabetes and hypertension, two independent predictors of adverse outcome in previous outcomes studies,3–6unfairly skewed the analysis. Discounting the supermorbidly obese patient population, obesity has been protective for morbidity in several studies, as duly noted by the authors. On the other hand, diabetes and hypertension have both been independent predictors of organ failure and mortality. Therefore, did the current study prove the increased risk of modified metabolic syndrome or simply prove that the preoperative presence of two independent risk factors (and one protective factor) is more significant than having one protective factor? Separating these two independent risk factors from obesity is important to determine whether the described effect sizes are independent of body mass index. Although the lack of these data in no way invalidates the study results in terms of identifying higher-risk profiles of obesity, if obesity was indeed protective, as is suggested in the literature, were patients with diabetes and hypertension but no obesity at greater risk of adverse outcomes? If so, are we truly using our risk assessment tools appropriately? These are yet unresolved questions; however, Glance et al.  1have provided the initial spark that could ultimately cast light on them.

University of Michigan Medical School, Ann Arbor, Michigan.rsatyak@med.umich.edu

References

1.
Glance LG, Wissler R, Mukamel DB, Li Y, Diachun CA, Salloum R, Fleming FJ, Dick AW: Perioperative outcomes among patients with the modified metabolic syndrome who are undergoing noncardiac surgery. Anesthesiology 2010; 113:859–72
2.
Ramachandran SK, Kheterpal S, Consens F, Shanks A, Doherty TM, Morris M, Tremper KK: Derivation and validation of a simple perioperative sleep apnea prediction score. Anesth Analg 2010; 110:1007–15
3.
Arozullah AM, Daley J, Henderson WG, Khuri SF: Multifactorial risk index for predicting postoperative respiratory failure in men after major noncardiac surgery: The National Veterans Administration Surgical Quality Improvement Program. Ann Surg 2000; 232:242–53
4.
Cunningham EJ, Bond R, Mehta Z, Mayberg MR, Warlow CP, Rothwell PM; European Carotid Surgery Trialists' Collaborative Group: Long-term durability of carotid endarterectomy for symptomatic stenosis and risk factors for late postoperative stroke. Stroke 2002; 33:2658–63
5.
Giles KA, Hamdan AD, Pomposelli FB, Wyers MC, Siracuse JJ, Schermerhorn ML: Body mass index: Surgical site infections and mortality after lower extremity bypass from the National Surgical Quality Improvement Program 2005–2007. Ann Vasc Surg 2010; 24:48–56
6.
Kheterpal S, Tremper KK, Heung M, Rosenberg AL, Englesbe M, Shanks AM, Campbell DA Jr: Development and validation of an acute kidney injury risk index for patients undergoing general surgery: Results from a national data set. Anesthesiology 2009; 110:505–15