Obesity Paradox Strengthened by New SCAAR Data in ACS

September 06, 2012

September 6, 2012 (Gothenburg, Sweden) — Further support for the concept of the obesity paradox has come from a large study of patients with acute coronary syndrome (ACS) in the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) [1]. Those who were deemed overweight or obese by body-mass index (BMI) had a lower risk of death after PCI than normal-weight or underweight participants up to three years after hospitalization, report Dr Oskar Angerås (University of Gothenburg, Sweden) and colleagues in their paper, published online September 5, 2012 in the European Heart Journal.

"In patients who have a chronic disease, obesity seems to have some kind of protective effect--what this is we don't know, it's difficult to say," coauthor of the new research, Dr Kristjan Karason (University of Gothenburg, Sweden), told heartwire.

In an accompanying editorial [2], Drs Stephan von Haehlin, Oliver Hartmann, and Dr Stefan D Anker (Charité Medical School, Berlin, Germany) agree that this research strengthens the existing evidence for the obesity paradox. They conclude that weight loss in patients with chronic illness and a BMI of < 40 kg/m2 "is always bad, and in fact not a single study exists to suggest that weight loss in chronic illness makes patients live longer."

Perhaps we should be less worried about patients who are overweight and have chronic diseases, as they seem to do fairly well.

But Karason says he feels this advice is taking things a step too far. He notes that heart-disease guidelines still recommend that patients should lose weight, "and I don't think we have enough data to answer the question of whether these patients should not lose weight." Still, he says, "perhaps we should be less worried about patients who are overweight and have chronic diseases, as they seem to do fairly well." But he says this stance does not extend to the extremely obese (BMI > 35 kg/m2). While he and his colleagues did not have enough patients in this category to draw any firm conclusions, "I would recommend those with BMI > 35 kg/m2 to lose weight because they have a lot of other problems, comorbidities, and poor quality of life," he observes.

Obesity paradox should be recognized in guidelines

Angerås and colleagues remind readers that the obesity paradox refers to epidemiological evidence that obesity compared with normal weight is associated with counterintuitively improved health in a variety of disease conditions.

From the SCAAR registry, they identified almost 65 000 patients who underwent coronary angiography due to ACS. Of the patients, 84.4% had significant coronary stenosis while 15.6% had no significant stenosis. Patients were then further subdivided according to the treatment they received: medical therapy, PCI, or CABG. Patients were also separated into nine BMI categories, with the "lean" BMI category (21.0 to 23.5 kg/m2) used as the reference group. Patients were followed for a mean of 21 months.

The underweight group (BMI < 18.5 kg/m2) had the greatest risk for mortality. Medical therapy and PCI-treated patients with modest overweight (BMI 26.5 kg/m2 to < 28 kg/m2) had the lowest risks for mortality (hazard ratio 0.52 and HR 0.64, respectively).

And when BMI was studied as a continuous variable in patients with significant CAD, the adjusted risk for mortality decreased with increasing BMI to approximately 35 kg/m2, then increased.

In patients with significant CAD undergoing CABG and in those with no significant CAD, there was no difference in mortality risk in the overweight groups compared with the normal-weight group, however.

The researchers note a number of limitations to the study, including the fact that they did not have data on pharmacological treatment given to participants and therefore were not able to adjust for possible differences relating to therapy. But they did adjust for age, smoking status, history of malignancy, renal failure, and heart failure, among other factors.

The obesity paradox requires much more attention and deserves to be recognized in the guidelines.

"These data strengthen the concept of the obesity paradox substantially," the authors state. The relation between BMI and mortality showed the lowest risk among overweight or obese patients and the highest in underweight and normal-weight patients.

"The obesity paradox requires much more attention and deserves to be recognized in the guidelines," they conclude.

Angerås et al report no conflicts of interest. von Haehling reports receiving fees for consulting from Professional Dietetics, Solartium Dietetics, and Pfizer. Anker reports receiving fees for consulting from Professional Dietetics, Fresenius Medical Care, and Bosch. Hartmann is an employee of Thermo Fisher Scientific.