The Effects of Nocturnal Hemodialysis Compared to Conventional Hemodialysis on Change in Left Ventricular Mass: Rationale and Study Design of a Randomized Controlled Pilot Study

Michael Walsh; Braden J Manns; Scott Klarenbach; Robert Quinn; Marcello Tonelli; Bruce F Culleton


BMC Nephrology. 2006;7 

In This Article

Abstract and Introduction

Background: Nocturnal hemodialysis (NHD) is an alternative to conventional three times per week hemodialysis (CvHD) and has been reported to improve several health outcomes. To date, no randomized controlled trial (RCT) has compared NHD and CvHD. We have undertaken a multi-center RCT in hemodialysis patients comparing the effect of NHD to CvHD on left ventricular (LV) mass, as measured by cardiac magnetic resonance imaging (cMR).
Methodology/Design: All patients in Alberta, Canada, expressing an interest in performing NHD are eligible for the study. Patients enrolled in the study will be randomized to either NHD or CvHD for a six month period. All patients will have a full clinical assessment, including collection of biochemical and cMR data at baseline and at 6 months. Both groups of patients will be monitored biweekly to optimize blood pressure (BP) to a goal of <130/80 mmHg post-dialysis using a predefined BP management protocol. The primary outcome is change in LV mass, a surrogate marker for cardiac mortality, measured at baseline and 6 months. The high sensitivity and reproducibility of cMR facilitates reduction of the required sample size and the time needed between measures compared with echocardiography. Secondary outcomes include BP control, anemia, mineral metabolism, health-related quality of life, and costs.
Discussion: To our knowledge, this study will be the first RCT evaluating health outcomes in NHD. The impact of NHD on LV mass represents a clinically important outcome which will further elucidate the potential benefits of NHD and guide future clinical endpoint studies.

Despite advances in dialysis therapy, mortality and morbidity remain high for patients with end-stage renal disease (ESRD). For instance, the mortality of this very high-risk population remains at nearly 20% per year with death rates from cardiac disease that are 10-20 fold higher in dialysis patients than in the general population.[1] Only 16% of incident dialysis patients have normal hearts by echocardiography, with concentric left ventricular hypertrophy (LVH) present in 41% and systolic failure in 16%.[2] This is important since the presence of LVH is associated with a several fold increase in risk for both heart failure and mortality.[2,3]

Randomized trials that have attempted to demonstrate reduction in mortality among dialysis patients have generally been unsuccessful.[4,5,6,7,8] Even trials designed to impact surrogate endpoints, such as regression of LVH or LV dilatation, have been disappointing. Furthermore, there are very few interventions that have been shown to improve the poor health-related quality of life (HRQOL) observed in this population.

This difficulty of improving health outcomes may be due to the fact that ESRD is characterized by numerous complex metabolic and physiological abnormalities. Conventional hemodialysis (CvHD) does not normalize the majority of these abnormalities, and provides only a small fraction small molecular weight solute clearance compared with native kidney function.[9] In an attempt to improve urea clearance and clinical outcomes, nocturnal hemodialysis (NHD), a technique first developed in the 1970s, has received renewed attention. In NHD, patients perform dialysis at home; this is done five to six nights per week while they sleep.

Case control and cohort studies suggest that nocturnal hemodialysis may induce regression of LVH,[10,11,12] improve HRQOL,[13,14,15] and improve blood pressure control,[16,17,18] among other health benefits. However, observational data may lead to conclusions ultimately refuted by randomized clinical trials (RCT). Given the uncertainty associated with the observed outcomes and costs derived from non-randomized studies examining NHD,[19,20] it is important to have high quality data on NHD before widespread uptake of this new therapy occurs. We describe a randomized pilot trial comparing NHD (5 or 6 nights per week, 8 hours per night) and conventional hemodialysis (three times per week, four hours per session) with respect to their effect on progression of left ventricular mass measured by cardiac magnetic resonance imaging (cMR). Data on health-related quality of life, and measures of physiologic control, including blood pressure, anemia, calcium and phosphate metabolism and costs will be assessed as secondary outcomes.