In PAH, Is BMI Linked to Exercise Capacity, Hemodynamics?

Body mass index (BMI) impacts exercise capacity and hemodynamics among individuals with pulmonary arterial hypertension (PAH), according to a new study. 

The determination comes after the study findings showed that participants with obesity or underweight had altered pulmonary artery capacitance (PAC), pulmonary vascular resistance (PVR), and 6-minute walk distance (6MWD) compared with those who were of normal weight.

To reach this conclusion, the researchers analyzed patient data from 21 randomized controlled trials of PAH therapies between 1998 and 2014 that had been submitted to the US Food and Drug Administration. 

In all, data on 6408 patients were evaluated. Among these patients, based on their BMI, 3.7% had underweight (<18.5 kg/m²), 40.2% had normal weight (18.5-24.99 kg/m²), 29.7% had overweight (25-30 kg/m²), and 26.4% had obesity (≥30 kg/m²).

Compared with those who had normal weight, patients who had underweight were younger, more likely to be Asian, and more likely to have congenital heart disease. Also compared with those who had normal weight, patients with obesity were older, less likely to be Asian, and more likely to have idiopathic PAH.

After multivariate adjustment, patients with underweight or obesity had significantly shorter 6MWD and percent predicted 6MWD compared with patients with normal weight.

Compared with all other BMI groups, patients with obesity also had significantly higher PAC. However, there was no difference in PAC index between groups.

Meanwhile, PVR decreased with increasing weight status. No difference in PVR index was detected, though.

“Obese clinical trial participants with PAH had higher PAC, lower PVR, [and] shorter 6MWD, whereas underweight patients had lower PAC, higher PVR, and shorter 6MWD as compared to normal weight patients with no difference in PAC [index] or PVR [index],” the researchers concluded. “Whether these differences have an effect on response to treatment in these trials warrants investigation.”

—Colleen Murphy

Reference:

Minhas J, Appleby D, McClelland R, et al. Obesity and its relationship with exercise capacity and hemodynamics in pulmonary arterial hypertension (PAH). Am J Respir Crit Care Med. 2020;201:A2080. https://www.atsjournals.org/doi/pdf/10.1164/ajrccm-conference.2020.201.1_MeetingAbstracts.A2080