Recruitment of patients with chronic kidney disease and obstructive sleep apnoea for a clinical trial.

Obstructive sleep apnoea is common in chronic kidney disease (CKD) and may accelerate the decline in kidney function. Recruitment for a randomised controlled trial to address whether treatment of sleep apnoea with continuous positive airway pressure (CPAP) slows the progression of kidney failure may be challenging because sleep apnoea is often asymptomatic in this patient population. The present report outlines recruitment challenges and how to address them. Adult patients with CKD were recruited for a 12-month randomised, controlled, non-blinded, parallel clinical trial to evaluate the impact of CPAP therapy on kidney function. Patients completed a home sleep apnoea test and those that met pre-specified sleep apnoea and nocturnal hypoxaemia severity criteria were randomised to receive CPAP or no therapy. Although 1,665 patients were eligible to participate in the study over 3 years, only 57 (3.4%) were ultimately randomised. The sequential reasons (and number of patients) for recruitment failure were: no show at clinic appointment (137), insufficient recruiters to approach every eligible patient (461), on therapy for sleep apnoea (122), unable to provide informed consent (67), refused consent (645), home sleep apnoea test not completed (47) or inclusion criteria not met (116), and declined pre-randomisation education session (12). Many challenges limit effective recruitment, which may be addressed by hiring additional recruiters and increasing the awareness of sleep apnoea among patients with CKD. These findings can be used to improve recruitment strategies and the design of future studies.

Effect of CPAP Therapy on Kidney Function in Patients With Chronic Kidney Disease: A Pilot Randomized Controlled Trial.

BACKGROUND: OSA is common in chronic kidney disease (CKD) and may accelerate a decline in kidney function. It is not clear whether treatment of OSA with CPAP improves kidney function. RESEARCH QUESTION: Does treatment with CPAP improve kidney function in patients with CKD and coexisting OSA? STUDY DESIGN AND METHODS: A randomized, controlled, nonblinded, parallel clinical trial was performed of patients with stages 3 and 4 CKD and coexisting OSA comparing the effect of CPAP vs usual care on the estimated glomerular filtration rate (eGFR) and the urine albumin to creatinine ratio (ACR) over 12 months. RESULTS: Fifty-seven patients were enrolled and 30 were randomized to CPAP. They had moderately severe CKD (eGFR, 38.4 ± 1.5 mL/min/1.73 m2) and significant OSA and nocturnal hypoxemia (oxygen desaturation index: 23.9 events/h; interquartile range [IQR], 20.3 events/h; mean peripheral capillary oxygen saturation: 89.5%; IQR, 1.7%); 60% had baseline albuminuria (ACR, > 3 mg/mmol). No significant difference was found between CPAP and usual care in the change in eGFR and ACR over 12 months. Although some improvement in eGFR occurred with CPAP therapy in patients with a lower risk of CKD progression, this did not reach statistical significance. INTERPRETATION: Although CPAP did not provide additional renal benefits over usual care in all CKD patients, some evidence suggested that CPAP slowed the decline in eGFR in CKD patients with a lower risk of CKD progression. These preliminary data support the need for larger clinical trials exploring the effects of CPAP on kidney function. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT02420184; URL: www.clinicaltrials.gov.

Effect of CPAP therapy on kidney function in patients with obstructive sleep apnoea and chronic kidney disease: a protocol for a randomised controlled clinical trial.

INTRODUCTION: Obstructive sleep apnoea (OSA) is common in patients with chronic kidney disease (CKD) and may contribute to the progression of kidney disease either through direct effects of hypoxia on the kidney or indirectly through hypoxaemia-induced oxidative stress, endothelial dysfunction, inflammation, activation of the renin-angiotensin and sympathetic nervous systems, and hypertension. Treatment of OSA with continuous positive airway pressure (CPAP) improves many of these physiological abnormalities in patients with normal renal function, though to date there are no trials evaluating the effect of OSA treatment on kidney function in patients with CKD. The purpose of this study is to test the feasibility and efficacy of CPAP therapy in CKD patients with OSA. METHODS AND ANALYSIS: The study is a randomised, controlled, non-blinded, parallel clinical trial in which patients with established CKD are screened for OSA. Patients with OSA are randomised to either conventional medical therapy (control group) or medical therapy and CPAP (CPAP group) and followed for 1 year. The primary outcome is the change in estimated glomerular filtration rate. Secondary outcomes are the change in the urinary albumin/creatinine ratio, the Epworth Sleepiness Scale , Pittsburgh Sleep Quality Index and Kidney Disease Quality of Life questionnaire. ETHICS AND DISSEMINATION: Ethics approval has been obtained from the Conjoint Health Research Ethics Board (ID: REB15-0055). Results from this study will be disseminated through presentations at scientific conferences and publication in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT02420184; Pre-results.