Abstract: FR-PO917

Effect of Lower BMI on Mortality Risk in Older Patients Starting Dialysis Is Time-Dependent

Session Information

  • Geriatric Nephrology
    November 03, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Geriatric Nephrology

  • 901 Geriatric Nephrology

Authors

  • Polinder-Bos, Harmke A., University Medical Center Groningen, Groningen, Netherlands
  • Gansevoort, Ron T., University Medical Center Groningen, Groningen, Netherlands
  • Van diepen, Merel, Leiden University Medical Center, Leiden, Netherlands
  • Dekker, Friedo W., Leiden University Medical Center, Leiden, Netherlands
  • Hoogeveen, Ellen K., Jeroen Bosch Hospital, Den Bosch, Netherlands
  • Franssen, Casper F.M., University Medical Center Groningen, Groningen, Netherlands
  • Gaillard, Carlo A., University Medical Center Groningen, Groningen, Netherlands
Background

Lower body mass index (BMI) has consistently been associated with worse survival in older individuals in the general population and in chronic disease populations. Remarkably, in older dialysis patients no association of BMI with mortality was found. Therefore, we performed an in-depth analysis on this association in the NECOSAD cohort.

Methods

908 patients aged ≥65 years were followed from start of dialysis until death or kidney transplantation, and were divided into tertiles by baseline BMI (BMI <23 (lower), 23-26 (reference), >26 (higher) kg/m2). Because the hazards changed significantly during follow-up, the effect of BMI was modeled for the short-term (<1 year after dialysis initiation) and longer-term (≥1 years after dialysis initiation) using time-dependent Cox-regression models. Furthermore, differences between lower BMI patients who survived versus died during the first year of dialysis therapy were evaluated.

Results

During a median follow-up period of 3.8 year, 567 deaths occurred. Cumulative survival proportions at end of follow-up were 30%, 28% and 31% for the lower, middle and higher BMI groups, respectively. Lower BMI was associated with a higher short-term mortality risk (HR 1.57 [1.10-2.23] P=0.01), and a lower longer-term mortality risk (HR 0.77 [0.60-0.99] P=0.04), adjusted for age, sex, race, and smoking. Patients with a lower BMI who died during the first year of dialysis therapy had significantly more comorbidity, less physical mobility and ability to perform usual activities, and had lower albumin levels compared with those who survived the first year.

Conclusion

In older patients who start dialysis therapy lower BMI is associated with increased 1-year mortality. Remarkably, when surviving the first year of dialysis, patients with lower baseline BMI had a similar or even lower mortality risk compared with patients who had a normal or higher baseline BMI. Especially those older patients with lower BMI that have limited comorbidity and mildly or non-impaired physical function may benefit from having started dialysis.