Tall Non-Black Dialysis Patients Die Prematurely

Austin G. Stack MD., MSc., FRCPI. Professor and Foundation Chair of Medicine, Graduate Entry Medical School (GEMS),Consultant Nephrologist, University Hospital LimerickMedicalResearch.com Interview with:
Austin G. Stack MD., MSc., FRCPI.
Professor and Foundation Chair of Medicine, Graduate Entry Medical School (GEMS),Consultant Nephrologist,
University Hospital Limerick

Medical Research: What is the background for this study?

Dr. Stack: Height is an important proxy for nutritional health and published studies in the general population have generally shown that taller individuals liver longer. Dialysis patients have life spans that may be 1/5th that of the general population, and it is important to identify those characteristics that are associated with greatest survival. Few studies have described the relationship between adult height and survival in patients undergoing dialysis in the Unites States.

Our study, using data from the US Renal Registry, is the largest study ever conducted that has investigated the relationship with height and mortality risk in patients undergoing dialysis.

Medical Research: What are the main findings?

Dr. Stack: In over 1 million new dialysis patients, we found that

  1. To our surprise, and in contrast to studies in the general population; tallness was in general associated with higher mortality risk and shorter life spans. Thus our findings were the reverse of what is generally observed in the general US population (i.e. paradoxical).
  2. Patients in the tallest categories (highest quintiles) had the highest death risk, although they were differences between men and women and across race groups
  3. This paradoxical relationship was not explaining by concurrent illness, socioeconomic status, or differences in care provided to patients prior to dialysis, or after dialysis initiation.
  4. The effect was stronger in men than for women.
  5. The effect differed by race. The strong association of increasing height with death was observed for white, Asian and native American/Alaskan Natives, but not Black race.
  6. The duration of the dialysis treatment did influence the height-mortality association with higher mortality risks for taller patients who had received shorter treatment times.

Thus, unlike all other race groups, increasing height did not associate with higher death rates for black men and women.

In fact, for black patients, increasing height was associated with lower death risk, very similar to the general population.

Medical Research: What should clinicians and patients take away from your report?

Dr. Stack: Height exerts an important quantifiable effect on dialysis patient survival. It is an easily measured physical trait and an important prognostic marker in survival studies.

In general, tallness is associated with higher death rates for all race groups with the exception of Black race.

Overall, patients in the tallest categories had the highest risk of dying prematurely, although the association was stronger in men than in women, and the association was observed in white, Asian, and American Indian/Alaskan native patients, but not in black patients. (In fact, for black patients, increasing height was associated with a lower risk of premature death, as seen in the general population.)

Furthermore, our study found that the duration of dialysis treatment (in hours) modified the impact of height on life expectancy. Consequently, we believe that nephrologists who care for tall patients take this into consideration and ensure all patients are getting adequate dialysis.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Stack: Adulthood height is an anthropometric measurement that is determined by many factors, both genetic and environmental including the interplay of several childhood and adolescence environmental factors including intercurrent illness, nutrition, and socioeconomic circumstances.

Given that height is determined by many factors, it is unclear as to what components of height (bone mass, fat mass, muscle mass) actually contribute to survival.

Teasing out which of these (if not all of them) contribute to patient survival needs to be further explored in scientific studies.


M. E. Elsayed, J. P. Ferguson, A. G. Stack. Association of Height with Elevated Mortality Risk in ESRD: Variation by Race and Gender.Journal of the American Society of Nephrology, 2015; DOI:10.1681/ASN.2014080821

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Austin G. Stack MD., MSc (2015). Tall Non-Black Dialysis Patients Die Prematurely