Higher Body Mass Index is Associated with Lower Mortality Risk in Patients with Severe Pulmonary Hypertension
Embargo expired: 19-May-2014 5:00 PM EDT
Source Newsroom: American Thoracic Society (ATS)
Newswise — ATS 2014, SAN DIEGO ─ In patients with congestive heart failure, obesity and a larger waist size have paradoxically been associated with a better prognosis in the prior investigations. This effect, known as the obesity paradox phenomenon, is now being demonstrated in patients with severe pulmonary hypertension.
“Obesity-related illnesses, particularly obesity hypoventilation syndrome and sleep apnea, may play a role in the development of pulmonary hypertension, and so we examined whether the protective effects of obesity seen in patients with heart failure were also seen in these patients,” said researcher Jose Caceres, MD, of Jacobi Medical Center/Albert Einstein College of Medicine in the Bronx, NY. Pulmonary hypertension is high blood pressure in the arteries going to the lung.
“In our study of more than a thousand patients with significant pulmonary hypertension, we found that a higher body mass index (BMI) was associated with a reduced mortality risk, even after adjustment for baseline characteristics,” stated co-researcher M. Khalid Mojadidi, MD.
The study was presented at the 2014 American Thoracic Society International Conference.
The study involved 1137 patients with significant pulmonary hypertension (pulmonary artery systolic pressure > 60 mmHg), including 361 with a normal BMI (group A), 639 with obesity (Group B), and 137 with morbid obesity (Group C).
One-year mortality rates were 34.1%, in Group A, 22.8% in Group B, and 12.4% in Group C, yielding a lower relative risk (RR) for one-year mortality in groups B (RR 0.616; 95% confidence interval [CI] 0.484-0.530) and C (RR 0.306; 95% CI 0.184-0.508) compared to Group A. One-year readmission rates however did not significantly differ between groups.
“An obesity paradox may also occur in patients with significant pulmonary hypertension,” said lead author Dr. Ronald Zolty. “A possible mechanism underlying this phenomenon is increased levels of serum lipoproteins associated with increased body fat, which may play a role in neutralizing circulating toxins and inflammatory proteins.”
* Please note that numbers in this release may differ slightly from those in the abstract. Many of these investigations are ongoing; the release represents the most up-to-date data available at press time.
Mortality In Patients With Pulmonary Hypertension And High Body Mass Index
Type: Scientific Abstract
Category: 18.10 - Pulmonary Hypertension: Clinical – Treatment and Outcomes (PC)
Authors: J.D. Caceres1, M.K. Mojadidi1, P. Eshtehardi1 R. Zolty1; 1Jacobi Medical Center/Albert Einstein College of Medicine - Bronx, NY/US
Contrary to the conventional view that a lower body mass index (BMI) results in better health, recent studies suggest that obesity and a larger waist size have a favorable effect on the prognosis of patients with congestive heart failure. While obesity is a known risk factor for heart disease and heart failure, being overweight may provide some protective benefits. This is known as the “obesity paradox phenomenon”.
Obesity hypoventilation syndrome and sleep apnea have been well described as causes of pulmonary hypertension. However, there is currently a paucity of data on BMI as a predictor of outcomes in pulmonary hypertension (PH). The aim of this study was to determine whether an obesity paradox occurs in patients with severe PH.
From July 2002 to July 2012, the transthoracic echos of all patients were reviewed to find patients with severe pulmonary hypertension defined by a pulmonary artery systolic pressure > 60 mmHg. All patients with an ejection fraction < 50% were excluded from the study. Patients were divided into three groups stratified by their BMI:
Group A: Severe PH with a normal BMI (18 to 24.9 kg/m2)
Group B: Severe PH with obesity (BMI 25 to 39.9 kg/m2)
Group C: Severe PH with morbid obesity (BMI ≥40 kg/m2)
Inpatient and social security death records were used to determine one-year mortality. Hospital records were reviewed to determine one-year readmission rate for PH or cor pulmonale.
A total of 1137 patients (361 in Group A, 639 in Group B and 137 in Group C) were included in the study (mean age 71 ± 12; 69% female). One-year mortality rates in Group A, B and C were 34.1%, 22.8% and 12.4% respectively (p<0.001). Higher BMI was associated with a lower relative risk (RR) for one-year mortality in groups B (RR 0.616; 95% confidence interval [CI] 0.484-0.530) and C (RR 0.306; 95% CI 0.184-0.508) compared to Group A. There was no significant difference in one-year readmission rates between Group A, B and C (1.9%, 3.4% and 3.1% respectively; p=0.355)
This study demonstrates that higher BMI is associated with lower mortality in patients with severe PH. Our data suggests that an obesity paradox may also occur in patients with severe PH. Increased levels of serum lipoproteins that are associated with increased body fat may play a role in neutralizing circulating toxins and inflammatory proteins.