Is it time to wake up to online Hemodiafiltration?

There has been a lot of interest recently in online Hemodiafiltration (olHDF) with multiple studies  published in the past year. It is a technique which has gained favor in Europe (albeit with a lack of hard evidence) while being not utilized at all in the US for various reasons. HDF involves the addition of convective clearance, hemofiltration, to the diffusive treatment of hemodialysis (HD) which gives better clearance of middle sized uremic toxins. Very large volumes of plasma water are ultrafiltered using a high flux dialyzer with replacement solution needed to maintain fluid balance. As a large volume of fluid is infused directly into the patient, this infusate needs to be ultrapure with low levels of pyrogen and microbial contamination. The development of online generation of ultrapure replacement fluid, directly from the water treatment plant, has facilitated the roll out of olHDF in Europe. Safety concerns have also been addressed. Previously reported benefits, apart from middle molecule clearance, have included better phosphorous removal, improved intra-dialytic blood pressures, lower levels of EPO resistance, improved quality of life among others but hard outcome data has been lacking until recently. The past year has seen the publication of 3 randomized controlled trials examining olHDF versus conventional HD.

CONTRAST Study

The Convective Transport Study randomly assigned 714 patients to either olHDF or low flux HD. There was no difference between the groups in the primary outcome of all-cause mortality after a 3 year follow-up. However, in post-hoc analyses, receiving high dose olHDF (>22L of convective volume per session) was associated with a lower all-cause mortality compared to low flux HD (HR 0.62).

Turkish olHDF Study

This study randomized 782 patients to olHDF or high flux HD. The composite endpoint of all-cause mortality and nonfatal cardiovascular event rate was not different between the groups after a 2 year follow-up. However, again in a post-hoc analysis, a higher delivered dose of convective clearance (>17.4L, the median clearance) was associated with a lower risk of overall (RR 0.54) and cardiovascular mortality (RR 0.29).

Spanish olHDF Study

The latest study set out to deliver a high dose of replacement fluid and they succeeded (median convective volumes approximately 23L). They assigned 906 patients to either continue their current modality (mostly high flux HD) or switch to olHDF. The primary outcome of all-cause mortality occurred 30% less frequently in the olHDF group (p=0.01) after approximately 2 years.

Verdict: My previous experience with olHDF involved using it in an ad-hoc basis for patients with uremic symptoms despite ‘adequate’ KT/V urea or in patients with long dialysis vintage (extrapolating results from the HEMO study as high flux HD is a form of low dose HDF). Many European Nephrologists have presumed outcomes would be better but with very little data to back that up. We now have 3 RCTs suggesting a relationship between high dose olHDF and improved mortality. In our dialysis patients with such high mortality and with few interventions proven to impact this over decades, these results should be appreciated by the Nephrology community. It is at least time to reconsider the barriers to its use.

Posted by Paul Phelan

World Kidney Day 2011

Happy World Kidney Day 2011!  
This years theme is- 

protect your kidneys, save your heart.  

World Kidney Day began in 2006 and has continued to grow each year.  While every other organ system/disease has had a day/month for quite some time, it took a while to add our favorite organ (the kidney) to this list.  Here are the last 5 themes for world kidney day.

2006  Are your kidneys OK?

2007  Common, harmful and treatable

2008  Amazing kidneys

2009  Protect your kidneys: Keep your pressure down

2010  Protect your kidneys: Control Diabetes

This years theme is fitting because chronic kidney disease (CKD) alone has been established as an independent risk factor for cardiovascular disease (CVD). A nice editorial from ISN/International Federation of Kidney Foundations World Kidney Day Committee is published online for free here outlines the lack of attention CKD is given by world governments and public health authorities. This day helps give much needed attention to CKD and hopefully will lead to more awareness and eventually more therapies. Increased recognition of CKD will hopefully lead to more aggressive therapies for blood sugar, blood pressure and cholesterol. Which will in turn will lead to few patients developing CVD and ESRD.

What else can World Kidney Day do? We have long recognized the 20- to 30-fold increase in CVD in patients with ESRD. Much attention has been given to ESRD care. However, we have done little to impact cardiovascular mortality in patients with ESRD. Again, World Kidney Day can help give more attention to this growing problem as well. Expanding home dialysis options (daily home hemo and peritoneal dialysis) for patients on hemodialysis. This will need to be tackled on many fronts 1. Physician training and acceptance  2. Increasing infrastructure at dialysis units to deal with patient training and call system for issues related to nocturnal dialysis  3. Educating the public to know that this option can be performed safely and effectively.  4. Improving reimbursement programs to allow providers to utilize these options.

Some of the fellows at Duke will be volunteering at the Raleigh NKF KEEP program this weekend to celebrate World Kidney Day.  Lets spread that word about kidney disease so we can reverse this growing epidemic!