How Often Should We Sample Hb Levels In Dialysis Patients?

By Peter Laird, MD

It is interesting to understand that many of our practices in medicine are not based on clinical evidence, but instead on financial factors.  However, with the advent of the bundled payment for renal dialysis services, the issue of lab tests which were previously separately billable, those related to routine dialysis evaluation are included in the bundle which shall put several tests at risk of reduced frequency.  An interesting study quite timely from Louisville, Kentucky looked at the question of what is the optimal sampling frequency for Hb measurements:

Determining Optimimum Hemoglobin Sampling for Anemia Managemet from Every-Treatment Data:

Results: The most accurate Hb estimation is achieved when monitoring 8× per month (Hb_err = 0.23 ± 0.05 g/dl), but it exceeds the accuracy of the measurement device. The estimation error increases to 0.34 ± 0.07 g/dl when monitoring 4× per month, 0.39 ± 0.08 g/dl when monitoring 2× a month, and 0.45 ± 0.09 g/dl when monitoring 1× per month. Estimation error comparable to instrument error information is as follows: 8× per month, 15 patients; 4× per month, 22 patients; 2× per month, 6 patients; 1× per a month, 6 patients.

Conclusions: Four times a month is the clinically optimal Hb monitoring frequency for anemia management.

The accuracy of Hb measurements and adjustment of Iron and EPO requirements is an important adjunct to dialysis therapy tied directly to mortality based on high or low values. I suspect many dialysis units will be tempted to monitor Hb no more than twice a month in otherwise stable patients with the pressure of standard labs included in only one monthly payment for all dialysis services. This is one laboratory of great clinical importance that in my opinion is at risk of the financial managers making decisions based on what is best for the dialysis company instead of what the clinical evidence from this one study suggests is best for the patient.   Follow up studies of the impact of the bundle are needed to see how the majority of units respond on Hb management as well as the many other clinical interventions subject to the values of monthly labs.

Comments

[Brian Riddle, NxStageUsers]

I believe that monitoring the Hb level should be based on the patients needs.
We all tolerate and absorb epo/aranesp/iron or any other variations of the drugs differently. thus requiring different levels of monitoring than others.
It should not be based off of an equation, but rather the individual's needs. Some patients, including myself, need to keep a lower Hb as this affects my fistula pressures. If I were to keep my Hb in the recomended range, then I have issues with stenosis. By watching my Hb more closely, I have now gone over 300 days without the need for an angio whereas before I needed them every 2.5 - 3 months. Small veins + thicker blood = higher pressures and greater chances of clotting.
I also beleive that patients needs to be involved and know what level suits them best and work with their medical team to keep track as an individual rather than basin results off of group data.

[Peter Laird, MD]

Dear Brian, thank you for your insightful comments describing some of the difficulties of anemia management not only for yourself, but many other people as well. One of those complications as you note is indeed access clotting which is significantly increased with the use of ESA's. The thickness of the blood, called viscosity in the literature, is greatly enhanced by ESA's but there are likely other factors involved in the access clotting issue apart from the levels of Hb alone.

The main point of my article is the changing reimbursement between the old method where laboratory tests were seperately billable thus in many instances generating income for the dialysis unit to the new method under the bundle where routine monthly tests are all inclusive imposing a financial burden to the dialysis provider the more tests they perform. The likely outcome is that many patients will not receive Hb testing more than twice a month I suspect for cost cutting reasons.

The article I cited points out that adjustment of treatment parameters for Hb is best done on a weekly basis to achieve the targeted goals of therapy. Once, again, I suspect that the once weekly tests will be cut to once bi-weekly placing patients at risk of not meeting their target Hb which may impact clinical outcomes in a negative manner.

This may be the best way in which individual patients can achieve their own unique goals based on the entire clinical presentation for that specific patient. We will need to watch in follow up studies how dialysis providers implement Hb management after the bundle is fully implemented.

[greg10]

Thank you Dr. Laird for posting this and Brian Riddle for linking this from the nxstageusers site. Brian, how have you been titrating your epoetin and how are you doing your Hgb measurements?
I am a caretaker for my elderly father on hemodialysis. I had posted in another forum that we were contemplating on using a point-of-care Hgb meters which cost about $1.25 per test. We settled on using the Stat-site Hgb meter and we have been testing Hgb every time we dialyzed, which is 5x per week. We have been titrating by injecting 2500 units of epoetin subcutaneously and cutting back on the injections as we approach 11 g/dl of Hgb. Just by doing these tests, I concluded that we can cut back epoetin by about 4 fold from the prescribed IV-push epoetin and still maintain a safe level of Hgb. It seems to me, as a newbie, that the clinics should provide these point-of-care meters as a cost effective way of reducing waste and providing better care.

[Peter Laird, MD]

Dear Greg10. I am unaware of any programs that do this sort of monitoring with their patents. I must confess that if done safely without additional risk of infection, it could potentially be much akin to the self monitoring and regulation of insulin by diabetic patients that greatly improves care in close concert with their medical teams. Interesting concept, thank you.

[Sample For Research]

Wow! Thanks! I've already bookmarked the site & saved a couple reports!