Research Viewpoints Treatment Session Time: How Does it Influence Mortality Risk in Elderly Hemodialysis Patients?

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Ko GJ, Obi Y, Soohoo M, Chang T, Choi SJ, Kovesdy CP, Streja E, Rhee CM, Kalantar-Zadeh K: No Survival Benefit in Octogenarians and Nonagenarians with Extended Hemodialysis Treatment Time. Am J Nephrol 2018;48:389–398

The elderly continue to be a growing segment of patients with end-stage renal disease (ESRD) who are treated by dialysis. As expected, they have a mortality rate largely because of the concomitant burden of comorbidity. The impact of treatment modality and especially treatment session time with hemodialysis (HD) on mortality risk remains uncertain.

Ko and colleagues conducted an observational retrospective study of 112,026 incident HD patients, all 80 years or older at the inception of dialysis treatment (usually thrice weekly) starting between 2007 and 2011. All-cause mortality (ACM) adjusted for 10 co-morbidity factors, and for nutrition-inflammatory parameters, was the outcome of interest. Interestingly, despite many clinical recommendations to the contrary, elderly patients (≥ 80 years of age) tended to have the shortest treatment session times (median = 211 minutes) during the first 91 days after initiation of treatment. Longer treatment times were associated with better survival in those under 80 years of age, but not in those of age 80 years or more. Very short treatment times (< 210 minutes) were associated with increased mortality risk at all ages. Treatment times ≥ 240 minutes were associated with a trend toward higher mortality risk in the elderly (HR = 1.10; 95 % CI = 0.99 – 1.20 reference group 210 – 239 minutes) but the clinical significance of this observation is highly uncertain.

As this study is purely associative in character, no inferences can be made with high confidence that the observed impact of treatment times on mortality are causally related. The crude mortality rates for the entire all ages cohort was 135 deaths per 1000 treatment years. The lowest HR for mortality was seen with a treatment time of 210 – 240 minutes in the age 80 year plus group. The strength of this study lies in the large number of nationally representative patients included in the cohort. An attempt was made to correct for the impact of multiple comorbidities. The association of trend for a worsening mortality risk with extended treatment time (≥ 240 minutes) is an interesting finding, but it might be attributed to a reverse causality phenomenon. In addition, the mortality risk augmentation by short dialysis treatment times (≤ 210 minutes) regardless of age, is a finding that deserves much attention. This observation suggests that a minimum treatment session length (? > 210 minutes) should be recommended for most patients starting dialysis, regardless of age. A value of 240 minutes for the optimal treatment starting length seems advisable for most patients under 80 years of age. The optimal range of treatment session times for those starting dialysis over 80 years of age is deserving of further investigation by prospectively designed interventional trials.