Preserving Residual Renal Function: The Ignored Goal

[Hemodoc]

By Peter Laird, MD

Several studies have conclusively shown that residual renal function  (RRF) is an important factor in dialysis patient survival. Douglas Shemin, MD and his group followed 114 hemodialysis patients and categorized them according to the presence or absence of preserved residual function.

Residual renal function and mortality risk in hemodialysis patients

This prospective observational study of all 114 patients at a single community-based freestanding HD center is designed to examine the impact of residual renal function (defined as renal urea clearance and renal creatinine clearance derived from 24-hour urinary volumes) on mortality over a 2-year period. During that period, 50 deaths occurred in 114 patients. The presence of residual renal function was protective against mortality (odds ratio for death, 0.44; 95% confidence interval, 0.24 to 0.81; P [equals] 0.008), even after adjustment for duration of dialysis treatment, age, smoking, presence of diabetes, presence of cardiovascular disease, serum albumin level, and urea reduction rate. In conclusion, the presence of residual renal function, even at a low level, is associated with a lower mortality risk in HD patients.

There are several strategies to preserve residual renal function including starting first with peritoneal dialysis as PD has greater preserved RRF than conventional hemodialysis, ultra-pure dialysate and biocompatible membranes, ACE Inhibitors, ARB's and calcium channel blockers, controlling ambulatory blood pressure, avoiding nephrotoxic drugs, and lastly to avoid hypotensive episodes and dehydration hemodialysis sessions.

Predictors of the rate of decline of residual renal function in incident dialysis patients

Conclusions: rGFR is better maintained in PD patients than in HD patients. The associated factors such as a higher diastolic blood pressure, proteinuria, dialysis hypotension and dehydration can either be treated or avoided.

Despite the clear survival advantage of preserving RRF, many patients continue to experience significant episodes of intradialytic hypotension which many rightly believe, in my opinion, avoidably contributes to rapidly declining residual renal function.

Europe has more stringent water quality standards supporting ultra-pure dialysate while America continues to largely ignore the positive outcomes with ultra-pure dialysate. NxStage utilizes their pureflow system which their published accounts show an ultra-pure dialysate level.  An important aspect of residual renal function is whether more frequent dialysis with gentler ultrafiltration will positively impact RRF in the same magnitude that PD offers to patients.  Studies are greatly needed in this area.

Patients on home hemodialysis should discuss the additional factors known to preserve residual renal function with their health care team and simply remind anyone that they encounter in a hospital setting that they need to offer treatments specifically designed to avoid further damage to their kidneys even though they are already on dialysis. Unfortunately, despite the known benefits, concerted efforts to preserve RRF are largely ignored even within the nephrology community, let alone among the many other physicians a dialysis patient will especially encounter in a hospital setting. In this instance, the dialysis patient and his care partners will need to remind each health care professional of the importance of designing a care plan around the central goal of preserving the residual renal function. It truly is a matter of life and death for dialysis patients.

http://www.hemodoc.com/2011/03/preserving-residual-renal-function-the-ignored-goal.html

[MooseMom]

Peter, do you think that the underlying cause of a patient's renal failure has any bearing on how much residual function s/he has and/or for how long?

I've taken an ACE inhibitor for years, but I've never taken an ARB.  In fact, I had not heard of ARBs until recently.  Is this something I should discuss with my neph?  Are the two often taken in concert?

[Hemodoc]

Peter, do you think that the underlying cause of a patient's renal failure has any bearing on how much residual function s/he has and/or for how long?

I've taken an ACE inhibitor for years, but I've never taken an ARB.  In fact, I had not heard of ARBs until recently.  Is this something I should discuss with my neph?  Are the two often taken in concert?

Yes, several studies document those with diabetes and/or vascular disease have loss of residual renal function at a higher rate than those patients with no or few co-morbid diseases.

The issue of ARBs and ACE Inh at the same time also appears to be a settled issue in a negative sense that this combination should be avoided for a variety of reasons.  By themselves, they each contribute to preserving residual renal function, but  in combination together, they significantly increase several complications associated with their use.  Interestingly, several years ago, the dual combination of an ACE Inh and an ARB was all the rage.  We know better now.  It should be avoided.  ACE Inh appear to have longer data points and perhaps more efficacy than ARBs but time will tell as well with the ARBs. For people like me with a dry cough from Prinivil, Cozaar is my only choice with our formulary right now.  Calcium channel blockers have excellent data showing benefit in preserving renal function as well and can be used in combination with either an ACE Inh or an ARB.

[MooseMom]

Thanks for that, Peter.  I already take a calcium -channel blocker (norvasc), so I guess I'm well covered.  I do believe I have received very good pre-dialysis care, and I hope that carries on as I transition onto dialysis.

[Hemodoc]

Thanks for that, Peter.  I already take a calcium -channel blocker (norvasc), so I guess I'm well covered.  I do believe I have received very good pre-dialysis care, and I hope that carries on as I transition onto dialysis.

For me starting dialysis was a little anticlimactic since it was so long in coming to that point, a total of nine years for me to get used to the idea and deal with it.  The preparation you are doing now will serve you well.  Exercise, eating well, avoiding salt and controlling blood pressure goes a long way in the dialysis game. If you can get as much dialysis as possible, that completes the biggest hoops we have to jump through, but there are more as well you are aware.

[tyefly]

I unfortunately didnt not have much time to deal with residual function.. My kidney decline was over a period of months...  I did not have high blood pressure until I started loosing my renal function....  its like everything happen at once... I was put on lisnopril for several months and I did develop a bad cough...  so they put me on Cozaar and the cough went right away.... I have had a decline in residual function since I started dialysis and notice that when I dont do dialysis that day  I have more function....   I hope to continue residual function and I will talk to my health care team  about this....

[Willis]

I also have Iga Nephropathy and even though I was diagnosed via biopsy in Oct 2005 I know now that I first had symptoms at least 30 years ago. I'm scheduled to get a fistula on April 20th. My neph is open to me going on PD and if I decide to do that then I will get the PD catheter as soon after my fistula surgery as possible. My surgeon seems to think this is a good plan and I think it seems like a good idea to have the fistula as a back up.

Your article above is interesting. I'm having a hard time deciding whether I want to do CCPD or home hemo but it seems like maintaining residual function for as long as possible is a desirable goal. So that would be another positive for PD. I want to continue to work and exercise as much as possible and PD seems best for that. I just want to choose the modality which will give me the best chance to continue an active life. (I play tournament table tennis and play/practice 15-20 hrs per week.) I'm not sure if I'm asking a question here or not, but maybe looking for some assurance that PD is my best choice?

Now another question that I'm not sure is related or not. As part of my pre-surgery work up I had to undergo a stress test. I was told that I have one of the healthiest hearts they've seen in a 58 year old. But my cholesterol was very slightly high and the cardiologist prescribed some form of statin drug. Personally, I'm not big on taking drugs and I've refused to take statins for many years. I get the feeling sometimes that cholesterol just happens to be one of those things that seems to be objectively measurable and thus makes a good basis for prescribing "something" and making the patient feel like the doctor is doing "something." Not to mention the profits the drug companies make.

Well, sorry for the mini-rant, but in light of your research on maintaining renal function during dialysis, what is your opinion of statin drugs in general? If it depends on the specific drug, let me know and I will dig up the name of what I was prescribed.

Thanks
Willis

 

[Hemodoc]

I also have Iga Nephropathy and even though I was diagnosed via biopsy in Oct 2005 I know now that I first had symptoms at least 30 years ago. I'm scheduled to get a fistula on April 20th. My neph is open to me going on PD and if I decide to do that then I will get the PD catheter as soon after my fistula surgery as possible. My surgeon seems to think this is a good plan and I think it seems like a good idea to have the fistula as a back up.

Your article above is interesting. I'm having a hard time deciding whether I want to do CCPD or home hemo but it seems like maintaining residual function for as long as possible is a desirable goal. So that would be another positive for PD. I want to continue to work and exercise as much as possible and PD seems best for that. I just want to choose the modality which will give me the best chance to continue an active life. (I play tournament table tennis and play/practice 15-20 hrs per week.) I'm not sure if I'm asking a question here or not, but maybe looking for some assurance that PD is my best choice?

Now another question that I'm not sure is related or not. As part of my pre-surgery work up I had to undergo a stress test. I was told that I have one of the healthiest hearts they've seen in a 58 year old. But my cholesterol was very slightly high and the cardiologist prescribed some form of statin drug. Personally, I'm not big on taking drugs and I've refused to take statins for many years. I get the feeling sometimes that cholesterol just happens to be one of those things that seems to be objectively measurable and thus makes a good basis for prescribing "something" and making the patient feel like the doctor is doing "something." Not to mention the profits the drug companies make.

Well, sorry for the mini-rant, but in light of your research on maintaining renal function during dialysis, what is your opinion of statin drugs in general? If it depends on the specific drug, let me know and I will dig up the name of what I was prescribed.

Thanks
Willis

Dear Willis, sorry to hear that you are in need of renal replacement soon.  My take on all of the issues is that short of living donor transplant, nocturnal home hemodialysis at this time appears to have the best outcomes. The issue of preserving renal function with extended or daily dialysis simply has not been studied to date, however many speculate that it may actually preserve renal function better than conventional in-center hemodialysis but that is no proven.

PD has about equal survival to standard hemodialysis, nocturnal dialysis gets equivalent outcomes to cadaveric transplant.  For myself, the daily dialysis looked like my best bet.  PD unfortunately does not hold up as well after about two years in many patients.  The median survival for PD patients is 36-38 months depending on the data you look at. Nocturnal dialysis buys you more time compared side to side.

As far as fistulas go, I play the piano and it is not a problem but that is not quite to the degree of exertion as competitive table tennis. I know many are quite active, but I do go to extremes of protecting my left arm where I have my fistula.  I suspect you will be hard placed to find much data on this issue which in general is that of protecting the access at all costs.  In the end, each person makes their own decisions on how far that they push the activities.

In the end analysis it is a personal decision on which modality is right for your given situation.  We all have biases for or against certain aspects of one form of renal replacement over another.  Get the best information on all of your options, have detailed discussions with your family and medical team.  i suspect like most people, you will choose and feel comfortable with that choice based on your individual preferences coupled with the medical information.

As far as statins go, the SHARP trial did show a benefit to cholesterol lowering in CKD patients. One of the issues with statins in dialysis patients is the fact that sudden cardiac death in our population is multifactorial.  I do believe that there is a benefit to statins as evidenced by epidemiological studies showing patients with elevated chol at higher risk of death.  Statins can also slow the progression of renal disease as well. I take Pravachol which in my experience has fewer side effects than Mevacor, Lipitor or Zocor.  In my case, my pravachol lowered my total cholesterol over 100 points.  It is not touted as being as strong as some of the other statins, but it works well for me.  There are definite benefits to statin therapy and most folks do not have side effects, but some do.  I didn't really tolerate Lipitor or Zocor, but do well with pravachol.

We wish you the best.

God bless,

Peter

[MooseMom]

I was diagnosed with fsgs 20 years ago, but it was only 6 years ago that I began rigorous treatment.  Twenty years ago, apparently no one knew there was a link between CKD and high blood lipid levels.  I began taking statins because my cholesterol was 550 (which was a shock because I had been something of a "health nut"), and we couldn't leave that untreated.  Like Peter, I take Pravachol, too, because I developed an allergy to Crestor and pravachol, despite being an older drug, has fewer side effects.  It has been incredibly effective for me.  With CKD, I would hesitate to leave untreated any elevation in blood lipids, but I'm more of a paranoid bent.

Willis, I'd be interested in what you and your doc finally decide to do re statins.  Keep us posted!  Thanks.

[Willis]

A few years ago I was taking Crestor I think (my wife is the family pharmacist so I can't keep up with all the details sometimes ) and I just knew something was wrong. When I stopped taking it I could tell that I felt better by the very next day!

Right now my cholesterol was 160-something which I think is just a few points over the high end of the normal range. Thanks for the info on the Pravachol. If that's not what I'm on I'll see if I can change to that. I do know that what I just started taking is the inexpensive $4 generic version.

So many things to consider and so many choices... 

 

[Hemodoc]

A few years ago I was taking Crestor I think (my wife is the family pharmacist so I can't keep up with all the details sometimes ) and I just knew something was wrong. When I stopped taking it I could tell that I felt better by the very next day!

Right now my cholesterol was 160-something which I think is just a few points over the high end of the normal range. Thanks for the info on the Pravachol. If that's not what I'm on I'll see if I can change to that. I do know that what I just started taking is the inexpensive $4 generic version.

So many things to consider and so many choices... 

 

Yes, much better than 1959 and before.  You would be preparing to say good bye to this world, not looking at which renal replacement option to choose.  Having choices is a good thing.  We need to be thankful for living here in America as well.  In many places in the world, if you don't have the money to pay your own way in dialysis, you start to say goodbye.  Choices are good.

Best of luck sorting it all out with your medical team.

God bless,

Peter

[Willis]

Yes, Peter, I keep trying to be positive about the whole thing! Doesn't make decisions any easier though... 

I checked my meds and it's Pravastatin. I'm guessing that's a generic version of Pravachol and if so then I guess that's good.

Thanks for your help
Willis

 

[MooseMom]

I checked my meds and it's Pravastatin. I'm guessing that's a generic version of Pravachol and if so then I guess that's good.

Yes, pravastatin is the generic of Pravachol.

[boswife]

simvastatin?

[Hemodoc]

simvastatin?

Simvistatin = Zocor

Atorvastin = Lipitor

Rosuvastatin = Crestor

[boswife]

;-)  thanks hemodoc 

[Willis]

;-)  thanks hemodoc 

+1