Junkfood Science: Obesity Paradox # 14 — Serious illness

March 17, 2008

Obesity Paradox # 14 — Serious illness

Do fat people have a survival edge over thinner people when faced with a critical illness or do they fare worse? A study published in the January issue of Critical Care Medicine sought to find the answer to this question.

Researchers at the University at Buffalo School of Medicine and Biomedical Sciences, Buffalo, NY examined the records on more than 62,000 patients in intensive care units in the United States, Europe, Australia and the Middle East. The researchers were looking to see if obesity was associated with a better or worse chance for survival among critically ill patients.

They included in their meta-analysis all studies on ICU adult patients published since 1966 to February, 2007 which had reported weight status and mortality. As in all medical or surgical ICUs, the conditions that brought these patients to intensive care units varied, with most being respiratory problems, trauma and infections.

The first thing that became apparent in the data was that ‘obese’ people made up a remarkably lower percentage of ICU patients. Only 25% of the ICU patients were ‘obese’, compared with 75% who were not ‘nonobese’.

The second thing that the data showed, looking at the deaths that occurred during ICU stays, there was “no mortality difference between the obese and the nonobese group,” they said [RR, 1.00; 95% CI, 0.86–1.16].

When the researchers examined the overall survival rates throughout hospital stays, the ‘obese’ patients were associated with a 17% higher chance of surviving hospitalization compared to nonobese patients. Not a staggering correlation, but reportable because it counters what might have been expected.

Most healthcare professionals probably expected them to find more ‘morbidly obese’ patients in the ICU and that those patients would be at greater risk of dying. Lead author, Dr. Folu Akinnusi, told Canwest News that he hopes their findings will make doctors think twice about “subconsciously writing off the obese.”

“A lot of times, people have less of an expectation,” that obese will survive, he said. “If we know they’re not at greater risk, then you’re very likely to give them as much of a chance as everyone else and do the most you can for them.” This was a profound call for an end to weight discrimination in healthcare and among healthcare professionals.

The facts continue to contradict what our culture has come to assume about the health of ‘obese’ people. Some readers might be tempted to explain away this study’s findings as perhaps the thinner people had been sicker. These researchers thought of that. They also examined the severity of illnesses among the patients on admission, to rule out confounders that might skew the data, such as if thinner patients were sicker. Based on three different scoring systems (Acute Physiology and Chronic Health Evaluation II, Simplified Acute Physiology Score II, and Injury Severity Scores) they found there was no differences in the severity of illnesses between the ‘obese’ and ‘nonobese.’ Fat and thin people both get sick and thinness is no assurance of health.

How long patients had been on ventilators was a secondary outcome and they only had information on 42% of the ICU patients, but among those, ‘obesity’ was associated with being on ventilators 1.48 days longer than the ‘nonobese.’ But this difference in care had no effect on outcomes.

As the researchers wrote in their discussion section, the conflicting studies in the literature on obesity and ICU mortality are the byproducts of the selectivity of patients chosen for inclusion and the quality and design of studies. In explaining the worse outcomes reported in some early studies, they also suggested that ICUs may not have recognized that “the distribution, metabolism, protein binding and clearance of many drugs are altered in the obese, which usually result in underdosing of critical therapeutic agents.” More recent studies, however, have seen this trend reversed and studies have found no correlation between obesity and increased mortality, they said.

The researchers concluded that ‘mild obesity’ (BMI 30 - <35) but even more significantly, ‘moderate obesity’ (BMI 35 - <40), had a protective effect during critical illness compared to ‘overweight and ‘healthy’ weight patients. And contrary to popular wisdom, even “‘morbid obesity’ did not have an adverse effect on outcome.”

The researchers found that this study’s findings concurred with all the “currently available data in the obesity literature.” They went on to describe other studies reporting “the obesity paradox,” including the study of 108,927 acute heart failure patients with in-hospital mortality rates directly related to BMI (6.3%, 4.6%, 3.4%, and 2.4% for underweight, ‘normal’ weight, ‘overweight’, and ‘obese’ patients, respectively).

No one has researched why the ‘obese’ might do better, they said, but several theories have been advanced, including that fat cells (adipose tissue) help provide reserves beneficial during highly catabolic states (wasting) during critical illness. Another theory is that hormones secreted by fat cells (leptin and interleukin-10) have immune effects that might reduce the inflammatory response and improve survival during severe illness. “Leptin has a notable regulatory effect on T-lymphocytes and interferon-[gamma] production... Clinical studies in humans have also reported higher leptin levels in survivors of severe sepsis and septic shock than nonsurvivors. Interleukin-10 is another adipokine that possesses anti-inflammatory properties that help control the initial inflammatory response in critical illness...”

In examining their data closely, the diversities of weights and sizes had considerably less to do with mortality than popularly believed. ‘Overweight’ was associated with slightly improved outcomes compared to ‘normal’ weight, but ‘obese’ did better still. Despite the current trend of “excusing” those who are a few pounds ‘overweight,’ but saying that “being obese is deadly,” the body of evidence continues to show that those who make up the largest numbers in the ‘obese’ category do best of all.

The bottom line, is that obesity itself cannot be blamed for why people die.

The media and marketing departments for the anti-obesity interests will probably continue to do their best to ensure the public rarely hears of studies like this and of the evidence. Convincing us that fat is about health is essential to them. More importantly, it is to the benefit of any special interest to have consumers unable to or discouraged from critically examining and understanding the scientific evidence. People who just believe what they’re told to think are the most easily manipulated, frightened and hurt.

That’s why the greatest protection we all have from being taken advantage of, needlessy worried, or making decisions that are not in our best interests, is to think critically and dig for the facts, even if, and especially if, those ideas go against the zeitgeist.

The faithful will swallow it whole, so long as logical reasoning is never allowed to be brought to bear on it. — Adolf Hitler, Munich 1935, Voice of Destruction

© 2008 Sandy Szwarc

Bookmark and Share