Cardiorespiratory fitness assessed by cardiopulmonary exercise testing between different stages of pre‐dialysis chronic kidney disease: A systematic review and meta‐analysis

ABSTRACT Aim The burden of several cardiovascular risk factors increases in parallel to renal function decline. Exercise intolerance is common in patients with chronic kidney disease (CKD) and has been associated with increased risk of adverse outcomes. Whether indices of cardiorespiratory capacity deteriorate with advancing CKD stages is unknown. Methods We conducted a systematic review and meta‐analysis of studies assessing cardiorespiratory capacity in adult patients with pre‐dialysis CKD using cardiopulmonary exercise testing (CPET) and reporting data for different stages. Our primary outcome was differences in peak oxygen uptake (VO2peak) between patients with CKD Stages 2–3a and those with Stages 3b–5(pre‐dialysis). Literature search was undertaken in PubMed, Web of Science and Scopus databases, and books of relevant meetings. Quality assessment was undertaken with Newcastle‐Ottawa‐Scale. Results From 4944 records initially retrieved, six studies with 512 participants fulfilling our inclusion criteria were included in the primary meta‐analysis. Peak oxygen uptake (VO2peak) was significantly higher in patients with CKD Stages 2–3a versus those with Stages 3b–5(pre‐dialysis) [weighted‐mean‐difference, WMD: 2.46, 95% CI (1.15, 3.78)]. Oxygen consumption at ventilatory threshold (VO2VT) was higher in Stages 2–3a compared with those in Stages 3b–5(pre‐dialysis) [standardized‐mean‐difference, SMD: 0.59, 95% CI (0.06, 1.1)], while no differences were observed for maximum workload and respiratory‐exchange‐ratio. A secondary analysis comparing patients with CKD Stages 2–3b and Stages 4–5(pre‐dialysis), yielded similar results [WMD: 1.78, 95% CI (1.34, 2.22)]. Sensitivity analysis confirmed the robustness of these findings. Conclusion VO2peak and VO2VT assessed with CPET are significantly lower in patients in CKD Stages 3b–5 compared with Stages 2–3a. Reduced cardiorespiratory fitness may be another factor contributing to cardiovascular risk increase with advancing CKD. SUMMARY AT A GLANCE Exercise (cardiorespiratory) capacity is an often overlooked aspect of health in people with chronic kidney disease. Among people with CKD, markers of cardiorespiratory capacity are significantly lower in advanced CKD compared with earlier stages of CKD.