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Abstract: PO1042

Short-Term Association of Pre-Dialysis Calculated Serum Osmolality and Its Per-Quarter Change with Mortality in Maintenance Hemodialysis Patients

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Miyagi, Tsuyoshi, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Wenziger, Cachet, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Hsiung, Jui-Ting, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Narasaki, Yoko, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Miyasato, Yoshikazu, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Kimura, Hiroshi, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Iseki, Kunitoshi, Ryukyu Daigaku Igakubu Daigakuin Igaku Kenkyuka, Nakagami-gun, Okinawa, Japan
  • Tantisattamo, Ekamol, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Rhee, Connie, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Streja, Elani, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
  • Kalantar-Zadeh, Kamyar, Harold Simmons Center for Kidney Disease Research and Epidemiology, Orange, California, United States
Background

Homeostatic regulation of serum osmolality (SOsm) is critical for normal cellular function. Since kidney plays an important role in maintaining homeostasis, patients with kidney dysfunction might be unable to maintain homeostasis. However, it is unknown if SOsm can predict risk of mortality in maintenance hemodialysis (HD) patients.

Methods

We identified 16,402 patients who transitioned to maintenance HD in a large U.S. dialysis organization over 5 years (2007-2011) and had available calculated pre-dialysis SOsm (Sodium and Potassium and blood urea nitrogen (BUN) and Glucose) at baseline. We used the equation with the best fit between measured and calculated SOsm as follows: 2x([Na, in mmol/L]+[K, in mmol/L])+[Glucose, in mg/dL]/18+[BUN in mg/dL]/2.8. We divided the patients into ten groups based on their calculated SOsm (SOsm updated at quarterly intervals as a proxy of short-term exposure): <300, 300–<304, 304–<307, 307–<309, 309–<311, 311–<313, 313–<315, 315–<317, 317–<321 (reference group) and ≥321 mOsm/Kg, and calculated SOsm’s per quarter change from the date of first dialysis: <-8.0, -8.0–<-6.0, -6.0–<-4.0, -4.0–<-2.0, -2.0–<0, 0–<+2.0 (reference group), +2.0–<+4.0, +4.0–<+6.0, +6.0–<+8.0and ≥+8.0 mOsm/Kg. All-cause mortality risk was estimated using multivariable Cox models.

Results

The patients were 56% male, 48% non-white, and the mean age was 63 ± 13 (mean ± SD) years. Those with low calculated SOsm tended to be older. In time-varying analysis, the association between all-cause mortality showed that patients with the lowest calculated SOsm had the highest hazard ratio after fully adjusted (Figure A). We observed a U-shaped association between all-cause mortality and per quarter change in calculated SOsm such that SOsm change levels ±8.0 mOsm/Kg were associated with higher mortality risk (Figure B).

Conclusion

This result suggests that short-term and a wide range of changes in serum osmolality may increase the risk of all-cause mortality in hemodialysis patients.