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Underweight associated with highest mortality and costs after cardiac catheterisation



Barcelona, Spain – 26 Aug 2017: Being underweight, and not overweight, has the highest mortality, cost, length of stay, and readmission rate for those undergoing cardiac catheterisation, according to an analysis of more than one million patients presented at ESC Congress today.(1)

“Elevated body mass index (BMI) is a risk factor for coronary artery disease, yet studies have shown that overweight and obese patients actually have fewer complications and better clinical outcomes after revascularisation using percutaneous coronary intervention (PCI) – a phenomenon dubbed the obesity paradox,” said lead author Dr Afnan Tariq, an interventional cardiology fellow, Lenox Hill Hospital, New York, USA.

This study examined the association of BMI with in-hospital mortality, cost of care, length of stay, and rate of readmission within 30 days in patients undergoing cardiac catheterisation (coronary angiography) in 2013 in a nationally representative cohort.

Researchers used the National Readmission Database and Nationwide Inpatient Sample Database to retrospectively analyse discharge and readmission data. These are the largest all payer USA inpatient databases and include more than 35 million hospitalisations annually.

In 2013, 1 035 727 patients underwent cardiac catheterisation, of which 42% also received PCI with a stent or balloon. When categorised by BMI, 0.4% of patients were underweight (BMI<19 kg/m2), while 11.4% were obese (BMI 30.1–40 kg/m2) and 8.0% were morbidly obese (BMI over 40 kg/m2). Of those undergoing cardiac catheterisation, only 25.8% of the underweight patients went on to receive PCI, while 32.5% of the morbidly obese, 41% of the overweight, 41% of the obese, and 43.2% of the normal weight categories went on to have a balloon or stent (PCI) placed for coronary blockages (adjusted for comorbidities: all values p<0.001).

Despite the low percentage of cardiac catheterisations and lower rate of PCI compared to normal and overweight BMI groups, underweight patients were over three times more likely to die after cardiac catheterisation than morbidly obese patients and five times more likely to die than obese patients (6.0% mortality for underweight patients, 2.3% normal weight, 1.7% overweight, 1.2% obese, 1.9% morbidly obese, all values adjusted for comorbidities: p<0.001). Interestingly, despite the extreme BMI, morbidly obese patients had a lower mortality rate than normal weight patients and obese patients had the lowest mortality of all groups undergoing cardiac catheterisation.

Length of stay for underweight patients was more than double that of normal weight patients (10.5 days versus 5.1 days) resulting in nearly 50% higher costs for underweight patients ($USD 33 540 versus $USD 22 581). Morbidly obese patients had a slightly longer length of stay and higher costs compared to normal weight patients (6.2 days, p<0.01 and $USD 23 889, p<0.01).

After adjustment for comorbidities, underweight patients were 18% more likely than normal weight patients to be readmitted within 30 days (p<0.007), while morbidly obese patients were 8.2% less likely to be readmitted within 30 days (p<0.001). Overweight and obese patients had the lowest readmission rates, and were over 10% less likely to be readmitted than normal weight patients within 30 days.

Dr Tariq said: “The obesity paradox has flummoxed researchers for some time, and our research also flips the conventional wisdom that a higher BMI should portend a worse outcome. We found that the lower BMI group had worse outcomes across the board, including readmission, length of stay, cost, and mortality.”

“Furthermore, using the largest all payer publicly available database in the USA, we observe that obese and morbidly obese patients receive stents or balloons at a lower rate than normal weight patients, are less likely to be readmitted within 30 days, and have lower mortality than normal weight patients undergoing cardiac catheterisation,” he continued.

Dr Tariq concluded: “Further research will certainly add to the growing body of evidence, but the scales seem to be tipping in favour of higher BMI patients having better outcomes than normal weight patients. This study also reinforces the notion that the frail, those with the lowest BMI, have the worst outcomes - suggesting that when it comes to cardiac catheterisation, the smaller they are, the harder they fall.”

ENDS

Notes to editor

Sources of funding: none.

Disclosures: No disclosures for all authors.

References and notes
1) The abstract “Impact of BMI on clinical outcomes and readmissions after cardiac catheterization in the USA” will be presented during:
·   Poster session 1: PCI – Long-term outcome on Saturday 26 August from 11:00 to 16:00 in the Poster Area.
·    The press conference - Cardiac interventions - expanding applications on Saturday 26 August from 15:00 to 16:00.

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About the European Society of Cardiology
The European Society of Cardiology brings together health care professionals from more than 140 countries, working to advance cardiovascular medicine and help people lead longer, healthier lives.

About ESC Congress 2017
ESC Congress is the world’s largest and most influential cardiovascular event contributing to global awareness of the latest clinical trials and breakthrough discoveries. ESC Congress 2017 takes place 26 to 30 August at the Fira Gran Via in Barcelona, Spain. The scientific programme is here. More information is available from the ESC Press Office at press@escardio.org.

This press release accompanies both a presentation and an ESC press conference at the ESC Congress 2017. Edited by the ESC from material supplied by the investigators themselves, this press release does not necessarily reflect the opinion of the European Society of Cardiology. The content of the press release has been approved by the presenter.