There have been numerous studies reporting lower mortality rates in obese patients with various cardiovascular disorders than in nonobese patients, a phenomenon known as the "obesity paradox." Limited data exist regarding the effect of obesity on prognosis in patients with pulmonary arterial hypertension (PAH). We used the National Inpatient Sample database for years 2003 to 2011 to identify all patient hospitalizations aged ≥18 years with a primary diagnosis of PAH. Patients with a diagnosis of obesity were identified using Elixhauser co-morbidity measure provided in Nationwide Inpatient Sample database, based on International Classification of Diseases, Ninth Revision, Clinical Modification, codes and the diagnosis-related groups. Multivariable logistic regression was used to compare in-hospital mortality between obese and nonobese patients with PAH. Of the 18,450 patients with a primary diagnosis of PAH, 14.7% were obese. Obese patients with PAH were younger, more often women, and more often black compared with nonobese white patients. After risk adjustment for demographics, hospital characteristics, and baseline co-morbidities, obese patients with PAH had lower observed in-hospital mortality compared with nonobese patients with PAH (3.5% vs 8.1%; adjusted odds ratio 0.66, 95% confidence interval 0.51 to 0.85, p = 0.001). In conclusion, from a 9-year nationwide cohort of patients with PAH, we observed significantly lower risk-adjusted in-hospital mortality in obese patients compared with nonobese patients.
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