On Tuesday, the New York Times published an article about recent findings regarding obesity and critical illness. The conclusion? Heavy people survived more than thin people.
The study, led by James O'Brien of Ohio State University Medical Center and published recently in Critical Care Medicine, explored the relationship between BMI (Body Mass Index) and hospital mortality for critically ill adults. The research team gathered data over a 6-year period from 84 hospitals on 1,488 patients being treated for acute lung injury, all on mechanical ventilators. Over half the patient group had higher than normal BMIs. The data showed a clear relationship between BMI and survival to hospital discharge. Those patients with the higher BMIs enjoyed a lower risk of death than those patients with low BMIs.
Before obesity starts getting a good name…The conclusion only tells part of the story. The research team notes that the use of heparin differed in the patient groups. High BMI patients were more likely to get prophylactic treatment for blood clots – a possible factor in better outcomes. Also, the research team noted that those folks with low BMIs were potentially much sicker at the start – their low BMIs resulting from illness rather than health.
With obesity associated with so many deleterious health problems, this article was confounding and almost disturbing at first blush. However, the notion that very heavy people might be treated differently in a critical care setting because of their size helps make sense of the outcomes data. Similarly, outside a hospital thinness is easy to associate with robust good health. But inside an ICU, thin can look much more like frail and vulnerable to death.
Interesting findings to be sure – and a good reminder to peel the onion another layer or two in pursuit of the answer to "Why?"
Body mass index is independently associated with hospital mortality in mechanically ventilated adults with acute lung injury *.
Critical Care Medicine. 34(3):738-744, March 2006.
O'Brien, James M. Jr. MD, MSc; Phillips, Gary S. MAS; Ali, Naeem A. MD; Lucarelli, Maria MD; Marsh, Clay B. MD; Lemeshow, Stanley PhD
New York Times
Outcomes: Heavy People May Beat Critical Illness More Often
By ERIC NAGOURNEY
Published: May 9, 2006