Check out this site. This site lists studies being done using the NxStage. It gives contact persons if you are interested in participating. Most are dependent on where you live.
http://clinicaltrials.gov/ct2/results?term=NxStageSome of the studies are:
Comparison of Nocturnal Hemodialysis (NHD) and Short Daily Hemodialysis (DHD) With the NxStage® System One™
Phosphorus and Calcium Removal During Long Hemodialysis Treatment Sessions
FREEDOM: Following Rehabilitation, Economics and Everyday-Dialysis Outcome Measurements Study
Conditions: