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Abstract: SA-PO1006

Anion Gap Predicts Early Mortality After Starting Dialysis in the Elderly

Session Information

Category: Dialysis

  • 701 Dialysis: Hemodialysis and Frequent Dialysis

Authors

  • Arai, Yohei, National Center for Global Health and Medicine, Tokyo, Japan
  • Tanaka, Hiroyuki, Yokosuka Kyosai Hospital, Yokosuka, Japan
  • Sakamoto, Emi, National Center for Global Health and Medicine, Tokyo, Japan
  • Shioji, Shingo, Yokosuka Kyosai Hospital, Yokosuka, Japan
  • Kondo, Isao, National Center for Global Health and Medicine, Tokyo, Japan
  • Suzuki, Minami, National Center for Global Health and Medicine, Tokyo, Japan
  • Katagiri, Daisuke, National Center for Global Health and Medicine, Tokyo, Japan
  • Tada, Manami, National Center for Global Health and Medicine, Tokyo, Japan
  • Hinoshita, Fumihiko, National Center for Global Health and Medicine, Tokyo, Japan
Background

The kidney has the principal role in the maintenance of acid-base balance. Metabolic acidosis develops due to reduced renal function and excretion of the daily acid load. It is well known that uremia causes an increase in the serum anion gap (AG). However, it is not known whether changes in AG is associated with mortality after starting dialysis. Therefore, we investigated the association between AG and early mortality after starting dialysis in elderly patients with end-stage renal disease (ESRD).

Methods

We conducted a retrospective cohort study to investigate the association between AG and early mortality after starting dialysis in the elderly. The cohort consisted of patients aged 75 years old or older who started dialysis for ESRD at the National Center for Global Health and Medicine from 2010 to 2017 and at Yokosuka Kyosai Hospital from 2007 to 2011. They were stratified into three groups (G1-3) based on delta AG (ΔAG). ΔAG was calculated using a following equation, ΔAG = serum sodium level - (serum chloride level + serum bicarbonate level) - 12. The primary outcome was death within a year of the start of dialysis. Data were analyzed using Cox proportional hazard models with adjustments for baseline characteristics.

Results

We enrolled 254 patients (males, 59%). Median ΔAG was 2.6 (G1, >3, n=111; G2, 0-3, n=103; G3, <0, n=40). During a mean follow-up of 320 days, the primary outcome was observed in 43 patients. G1 and G3 had significantly higher hazard ratios (HR) for the primary outcome than G2 (G1, HR 2.47, 95% confidence interval 1.13-5.37; G3, HR 3.86, 95% confidence interval 1.62-9.16). After adjusting for baseline characteristics, G1 had significantly higher adjusted hazard ratio (aHR) for the primary outcome than G2 (G1, aHR 3.63, 95% confidence interval 1.56-8.45; G3, aHR 2.33, 95% confidence interval 0.88-6.19).

Conclusion

It is noteworthy that there is an obvious J-curve phenomenon between AG and early mortality after starting dialysis in the elderly.