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Prevalence of morbid obesity increasing in PCI patients
The proportion of morbidly obese patients undergoing PCI increased 91% from 1998 to 2009, and these patients are at greater risk for morbidity and mortality, according to new study results.
Researchers examined the prevalence of morbid obesity (BMI >40) among 227,044 PCI patients enrolled in the Blue Cross Blue Shield of Michigan Cardiovascular Consortium registry from 1998 to 2009. Patients were divided into four categories: lean (n=43,346, 19.1%); overweight (n=82,487, 36.6%); sub-morbidly obese (n=84,479, 37.2%); and morbidly obese (n=16,730, 7.4%).
In 1998, 33.5% of patients presenting for PCI were sub-morbidly obese and 4.38% were morbidly obese. In 2009, 38.08% of patients were sub-morbidly obese and 8.36% were morbidly obese.
The study also compared in-hospital outcomes, including in-hospital death, emergency CABG, all CABG, contrast-induced nephropathy, nephropathy requiring dialysis, post-procedure transfusion, stroke/transient ischemic attack, MI, major adverse cardiac events, vascular complications and gastrointestinal bleeding. Compared with overweight PCI patients (BMI 25-30), morbidly obese patients had lower risk for emergency and all CABG, but increased risk for contrast-induced nephropathy (adjusted OR=1.89; 95% CI, 1.7-2.11), nephropathy requiring dialysis (adjusted OR=4.08; 95% CI, 2.98-5.59), vascular complications (adjusted OR=1.31; 95% CI, 1.17-1.47) and mortality (adjusted OR=1.63; 95% CI, 1.33-2.0).
According to the researchers, the increased risk for contrast-induced nephropathy and nephropathy requiring dialysis may be related to the use of contrast media because obese patients may require multiple dye injections, which can raise the risk for complications. Another potential factor implicated is the difficulty of accurate renal function calculations in obese patients, as commonly used methods are not validated in patients with high BMI. Increases in vascular complications could be attributed to the high percentage of patients who underwent transfemoral PCI because high BMI can make access and vascular closure difficult.
The researchers said the increased mortality risk for morbidly obese PCI patients is an important finding because the morbidly obese group was the youngest on average (mean age, 59 years vs. 64 years in the overweight group) and more likely to undergo PCI for stable disease.
“These epidemiological changes have important implications for technical considerations of cardiac catheterization, design of the catheterization lab to accommodate these patients and, most importantly, for societal effort toward prevention of obesity,” the researchers concluded.
For more information:
Buschur ME. J Am Coll Cardiol. 2013; [published online ahead of print June 18].
Disclosure: The researchers report no relevant financial disclosures.
Perspective
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The findings are certainly expected with the rapid increase of obesity in the United States. I was surprised not only at the high percentage of patients who were morbidly obese, but at the declining minority who were lean. While the researchers found no impact on mortality, most studies have seen a U-shaped curve with morbid obesity and underweight patients having an increased mortality compared with overweight and obese patients. I wonder if one explanation could be that this study was not able to adequately adjust for baseline characteristics to show a difference.