Dr. Hugh Rayner

“How long does it take you to recover from a dialysis session?” refers to the recovery time for the ESRD HD patients. It has been shown to affect the mental and physical components of one’s health. There is limited information about the significance of patient-reported recovery time. In a recent study in AJKD, Rayner and colleagues look at a prospective cohort study of 6,040 patients in the DOPPS (Dialysis Outcomes and Practice Patterns Study) to see if recovery time predicted quality of life, mortality, and future hospitalization.  Corresponding author Dr. Hugh Rayner (HR) discusses this study with Dr. Veeraish Chauhan (eAJKD), eAJKD Contributor.

eAJKD: The focus of your analysis is recovery time (RT) after a hemodialysis session. Why is this important?

HR: For many patients, the intrusion of hemodialysis into their lives does not end when they leave the dialysis unit. It can take many hours for patients to return to normal after a treatment; for some it is not until the next day, meaning that they only have four days of ‘quality time’ in the week. This problem has not received the attention it deserves.

eAJKD: Traditional nephrology teaching has been that “more dialysis is better”. Increasing the duration of dialysis treatment is one of the interventions we apply in cases where dialysis dose seems inadequate. However, in your analysis, longer dialysis sessions were associated with longer RTs as well. So, how does a nephrologist know when a dialysis session length is not “too short,” but not “too long” either?

HR: Our observational study showed that longer treatment times were associated with longer recovery times. However the effect was not large; the odds ratio in the adjusted model was 1.05 (95% CI, 1.00-1.10) per 30-min longer HD session. Furthermore, we cannot be sure how these two variables are linked causally. The nephrologist should therefore use his or her clinical judgment with each patient to achieve the optimum dialysis clearance, treatment time, and symptom burden, including recovery time.

eAJKD: Beyond patients’ quality of life, are there other clinical variables affected by a longer RT?

HR:  Longer recovery time is strongly associated with the rates of hospitalization and mortality. This persists after adjustment for demographics, co-morbidities, and other treatment variables.

eAJKD: Patients reporting an recovery time over 12 hours had a 22% higher rate of first hospitalization, and 47% higher mortality than patients whose recovery time was under 6 hours. What could explain this difference?

HR: Recovery time seems to measure something about a patient’s health status that is not captured by other measures, such as comorbidity and laboratory results. One possibility is that recovery time measures the cumulative negative effects of kidney failure and/or hemodialysis treatments. For example, we know that HD treatment can have damaging effects on the heart and the brain. This makes recovery time a valuable outcome measure to include in clinical trials.

eAJKD: We have recently seen a push towards lower sodium dialysate given the association of higher sodium baths with increasing patient thirst after the treatment (leading to higher inter-dialytic weight gain, hypertension, volume overload, etc). However, in your analysis, higher dialysate sodium was associated with shorter recovery times and no increase in hospitalization or mortality. How would you advise clinical nephrologists when it comes to selecting an optimal dialysate sodium bath?

HR: The definitive answer to this question requires a randomized clinical trial comparing different dialysate sodium concentrations. I hope such a study is done to address this issue. In the meantime, our study suggests that units that have a uniform dialysate sodium concentration should use 140 mEq/L as standard. Units that vary the dialysate sodium between patients should consider increasing the concentration to 140 mEq/L if patients have a recovery time over 2 hours with a concentration at or below 138 mEq/L.

eAJKD: In this era where we are increasingly seeing an emphasis on the “quality” of healthcare (with reimbursements being tied to it), do you suggest including recovery time as a core clinical indicator of a dialysis patient’s health? Is it time to look beyond classic indicators like Kt/V?

HR: I agree that recovery time is a useful measure of dialysis patients’ health, and an informative patient-reported outcome. It is not clear whether it is a useful measure of the quality of hemodialysis care. For it to be used in that way, we need to have reliable evidence that recovery time can be reduced by modifying the treatment. That requires interventional clinical trials using recovery time as one outcome amongst others. I hope our study stimulates people to carry these out so we can move on from surrogate measures.

eAJKD: It seems counterintuitive why a fast ultrafiltration (UF) rate would be associated with shorter recovery time. What do you suppose could explain this?

HR: This may be an example of treatment-by-indication bias. Patients who experience a long recovery time after treatments with a fast UF rate may learn to reduce their salt and fluid intake and thus the UF rate. Alternatively, they may increase their treatment time to reduce the UF rate. This would leave those patients who tolerate a fast UF rate and have a short recovery time in the fast UF rate category in the study.

eAJKD: More patients in Japan seem to have shorter recovery times, with patients in Italy having longer recovery times. What might explain the geographical variability in the RT?

HR: The country differences are intriguing.  We were not able to do analyses within individual countries because of the relatively small sample size in each country. I am therefore reluctant to speculate on the reasons.

To view the article abstract or full-text (subscription required), please visit AJKD.org.