Obese Patients with PAH Have Lower Risk of Dying While Hospitalized, Study Finds

Obese people with pulmonary arterial hypertension (PAH) are less likely than patients of normal weight to die while hospitalized, finds a study examining the so-called “obesity paradox.”

The study, “Relation Between Obesity and Survival in Patients Hospitalized for Pulmonary Arterial Hypertension (from a Nationwide Inpatient Sample Database 2003 to 2011), appeared in The American Journal of Cardiology.

It has been extensively proven, and is now widely accepted, that obesity increases the risk of coronary heart disease, heart failure, hypertension and chronic obstructive pulmonary disease. However, several previous studies have also shown that obese individuals with cardiovascular diseases have lower mortality rates than patients of normal weight.

To shed light on this matter, researchers from several U.S.-based health institutions analyzed the potential link of obesity with in-hospital mortality rates among PAH patients.

Using the Nationwide Inpatient Sample (NIS) databases between 2003 and 2011, researchers collected information on 18,450 patients with diagnosed primary PAH, of whom 2,712 (about 14.7 percent) were obese. In general, the obese PAH patients were younger, more often women, and more often black.

The analysis showed that overall, obese PAH patients had a 44 percent lower risk of in-hospital mortality compared to non-obese patients.

“To the best of our knowledge, our study is the first to report the protective effect of obesity on in-hospital mortality in patients with PAH at a large, nationwide level,” researchers wrote.

It is still unclear why obesity protects people against cardiovascular and pulmonary diseases. Some studies have proposed that adipose, or fat, tissue may work as a buffer, thanks to the higher amounts of signaling proteins it produces. Others have suggested that the renin-angiotensin system, a hormone system involved in the regulation of arterial blood pressure, among other things, is involved.

“It is critically important to emphasize that this strong paradoxical association of obesity with favorable survival does not assume causation and should not be seen as encouragement for weight gain,” researchers emphasized. “However, the existence of the obesity paradox should stimulate research to elucidate the mechanism(s) behind this interesting observation and use it for potentially improving patient care and prognosis.”