Age-Obesity Interaction in Pulmonary Arterial Hypertension

No correlation between obesity and mortality in individuals with pulmonary arterial hypertension (PAH) was observed; however, the interaction of age and obesity with respect to survival showed an increased risk for mortality in young adults who were morbidly obese, according to a study published in CHEST.

Data were drawn from the French Pulmonary Hypertension Registry, and a cohort of 1255 incident participants were characterized with idiopathic, drug-induced, or heritable PAH. PAH in all participants was defined at baseline as PA pressure ≥25 mm Hg, pulmonary artery wedge pressure ≤15 mm Hg, and pulmonary vascular resistance >3 Wood units. The cohort was further categorized as underweight (BMI <18.5 kg/m²), normal weight (BMI 18.5-24.9 kg/m²), overweight (BMI 25-29.9 kg/m²), obese (BMI 30-34.9 kg/m²), or morbidly obese (BMI ≥35 kg/m²).

Of the 1255 individuals, 30.3% were obese and 11.2% were morbidly obese; comorbid conditions were more prevalent than in the other weight groups, including systemic hypertension, hypothyroidism, and diabetes. A higher frequency of drug-induced PAH was also reported in obese and morbidly obese, and more women were affected than men. Obese individuals also demonstrated worse exercise capacity but with less hemodynamic impairment. Coronary artery disease, hyperthyroidism, and smoking were equally prevalent across all groups.

Results of the study showed that overall survival was not significantly different among any of the BMI categories; specifically, obese and morbidly obese participants showed lower mortality rates at 1 year from baseline, similar mortality rates at 3 years, and higher mortality rates in the morbidly obese at 5 years. The interaction observed between obesity and age and survival rates was noteworthy. In comparing mortality rates of people who were younger than 65 (n=648) and 65 and older (n=607), the younger obese group had the highest risk for death (hazard ratio, 3.01; 95% CI, 1.56-5.79; P =.001).

Limitations included the retrospective nature of the study and grouping participants by BMI, potentially misclassifying those who gained weight from hypervolemia as a result of right heart failure, which would have inflated the mortality estimation in the obese cohort. In addition, missing data like the serial measurements of BMI over time or diuretic use could also lead to group misclassification.

No significant association between obesity and mortality was observed; however, a trend linking mortality to morbidly obese and underweight individuals was noted. Although interactions between obesity and gender or disease etiology were not observed, the obesity-age interaction showed a higher risk for death in younger morbidly obese people. These results suggest that younger, morbidly obese people should receive careful prognostic evaluation and may benefit from weight management activities as well as thoughtfully timed disease interventions.

Disclosures: Some investigators report financial support from Actelion Pharmaceuticals, Bayer, Novartis, Pfizer, GlaxoSmithKline, and Bristol Myers Squibb.

Reference

Weatherald J, Huertas A, Boucly A, et al. The association between body mass index and obesity with survival in pulmonary arterial hypertension [published online May 22, 2018]. CHEST. doi:10.1016/j.chest.2018.05.006