Abstract Body: Objectives
Prior studies suggest that cardiorespiratory fitness (CRF) is reduced among people with HIV (PWH), and that approximately 30% of PWH have chronotropic incompetence, or inability to increase heart rate during exercise. In the general population, chronotropic incompetence is associated with mortality and future cardiovascular disease. We sought to determine the prevalence of reduced CRF and chronotropic incompetence among older PWH and identify factors associated with reduced CRF and chronotropic incompetence.
Methods
The High-Intensity Exercise to Attenuate Limitations and Train Habits in Older Adults With HIV (HEALTH) study included people ≥50 years old with treated HIV, self-reported fatigue, and sedentary lifestyle. We included participants who completed baseline cardiopulmonary exercise testing (CPET) using a treadmill graded exercise protocol. We assessed CRF as peak oxygen consumption (VO₂) and chronotropy using adjusted heart rate reserve (AHRR). We defined reduced CRF as <85% predicted using the Fitness Registry and the Importance of Exercise National Database (FRIEND) equation and chronotropic incompetence as AHRR <80% (or <62% if on beta-blocker).
Results
Among 212 PWH screened, 142 consented, and 131 completed CPET with 4 excluded for poor quality gas exchange measurements. Median age was 57 years, 11% female, 17% Black and 12% Hispanic, and 43% obese (BMI ≥30). Mean peak VO₂ was 2.27±0.52 L/min or 25.7±5.8 ml/kg/min and mean AHRR was 87±20%. On CPET, 52/127 (41%) had reduced CRF <85% predicted and 35/130 (27%) had chronotropic incompetence. AHRR was correlated with 400-meter walk time (Spearman’s ρ=-0.37, p<0.001), PROMIS Fatigue score (ρ=-0.21, p=0.022) and PROMIS Function score (ρ=0.27, p=0.004); peak VO₂ was correlated with 400-m walk time (ρ=-0.26, p=0.006), 10x chair rise time (ρ=-0.22, p=0.018) and PROMIS Function score (ρ=0.19, p=0.044). Factors associated with chronotropic incompetence include chronic lung disease (p=0.041), marijuana use (p=0.042), and longer duration on antiretroviral therapy (p=0.029), but not age, BMI, current protease inhibitor use, or nadir CD4 count <200 cells/ml; clinical factors were not associated with reduced CRF.
Conclusions
Reduced CRF and chronotropic incompetence are common among older PWH and associated with worse physical function (both patient-reported and measured), suggesting that reduced CRF and chronotropic incompetence are clinically meaningful among older, sedentary people with HIV.