POS-293 Physical Activity In Renal Disease (PAIRED) and the effect on hypertension: a randomized controlled trial

Abstract

Hypertension is a key determinant of both cardiovascular (CV) events and progressive renal dysfunction in people with chronic kidney disease (CKD). Exercise is an effective strategy for blood pressure (BP) reduction in the general population but in CKD, hypertension is mediated by advanced vascular stiffness and volume expansion, and it is unclear whether exercise will mitigate this. The primary aim of this randomized trial was to determine the effect of exercise training compared to usual care on 24-hour ambulatory systolic blood pressure (SBP) in people with CKD at eight weeks. Participants with an eGFR of 15-44 ml/min per 1.73m2 and SBP >120 mmHg were recruited from a single center Canadian renal program. Participants were randomized, stratified by eGFR (<30 versus ≥30), to receive thrice weekly, moderate intensity aerobic exercise (50–60% heart rate reserve) supplemented with isometric resistance exercise, targeting 150 minutes per week and delivered over 24-weeks, or usual care. For exercise participants, Phase 1 (eight weeks) included an in-center weekly session and home-based sessions, and Phase 2 (16 weeks) included home-based sessions. The primary outcome was the difference in 24-h ambulatory SBP after 8 weeks of exercise training compared to control. Secondary outcomes included markers of CV risk, arterial stiffness (pulse wave velocity), aerobic capacity as measured by cardiopulmonary exercise testing and physical activity as measured by 7-day accelerometry. Outcomes were analyzed using mixed linear regression including fixed effects terms for time point, intervention, baseline eGFR, the outcome variable measured at baseline, and a random effects term for participant. Missing values were multiply imputed using chained equations with predictive mean matching. 44 people were randomized (30% of target enrolment) prior to stopping due to COVID-19. Of those randomized, 36% were female, mean age was 66, 55% were diabetic, and mean GFR was 29. Eligibility was 25%, primarily due to transportation barrier to attend the in-center sessions. Compared with usual care, there was no significant change in 24-ambulatory SBP at eight weeks 2.86 mmHg (95% CI -2.64, 8.35; P=0.31) or 24 weeks. There was no significant change in arterial stiffness as measured by pulse wave velocity. VO2peak improved by 235 ml/min in the exercise group (95% CI 18, 452; P=0.03) and there was a significant increase in BMI at 8 weeks 2.01 kg/m2 (95% CI 0.13, 3.89; 0.04) which was reflected in an increase in kilograms of fat free mass but this was not sustained at 24 weeks. The daily mean step count did not differ significantly between groups at 8 weeks, -62 (95% CI -821, 698) or at 24 weeks. In Phase 1, 90% of participants initiated at least 70% of the prescribed sessions versus only 48% of participants in Phase 2. Exercise training improved VO2peak and optimized body composition in people with moderate to severe CKD. However, the trial was under powered to detect a difference in blood pressure and additional trials are needed. To address limitations to trial recruitment resulting from a lack of transportation as well as the pandemic, effective home-based exercise interventions are needed.