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Abstract: TH-PO209

Hidden Hypocalcemia at the Initiation of Dialysis as a Risk Factor for Cardiovascular Disease and All-Cause Mortality

Session Information

Category: Bone and Mineral Metabolism

  • 402 Bone and Mineral Metabolism: Clinical

Authors

  • Yamaguchi, Satoshi, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Hamano, Takayuki, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Doi, Yohei, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Kubota, Keiichi, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Oka, Tatsufumi, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Sakaguchi, Yusuke, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Matsui, Isao, Osaka Univ Graduate School of Medicine, Osaka, Japan
  • Isaka, Yoshitaka, Osaka Univ Graduate School of Medicine, Osaka, Japan
Background

Lower corrected calcium (cCa) levels were reported to be associated with better prognosis among incident dialysis patients. On the other hand, hypocalcemia (HypoCa) often leads to arrhythmia and heart failure. Prognostic importance of true calcium (Ca) status defined by ionized calcium (iCa) remains to be revealed.

Methods

We performed a retrospective cohort study of incident hemodialysis (HD) patients. We collected the latest data just before the initiation of HD. We divided patients into 3 categories: Apparent HypoCa (low iCa: <1.15 mmol/L and low cCa: <8.4 mg/dL), Hidden HypoCa (low iCa and normal cCa), and Normocalcemia (NormoCa: normal iCa and normal cCa). The primary outcome was the composite outcome of all-cause death and cardiovascular diseases (CVD) after the initiation of HD. Using log-rank tests, Kaplan-Meier curves, and cox proportional hazards models, we examined whether Ca status predicts the primary outcome.

Results

Among the enrolled 321 patients, 75% of the patients showed true HypoCa defined as iCa <1.15 mmol/L, 57% of whom showed Hidden HypoCa. Over a median follow-up period of 31.5 months, 31% of the patients reached the primary endpoint. The risk for the primary outcome was not significantly different between HypoCa and normocalcemia defined by cCa. In contrast, patients with true HypoCa had higher risk than patients with normal iCa levels (Figure). In univariate analysis, Hidden HypoCa was significantly associated with increased risk for death or CVD compared with NormoCa (hazard ratio [HR], 2.35; 95% confidence interval [CI], 1.27-4.32), whereas Apparent HypoCa was not. Even after adjustment for age, sex, eGFR, diabetes, QTc prolongation, serum albumin, phosphate, and ALP levels, Hidden HypoCa was associated with significantly higher risk (HR, 2.28; 95% CI, 1.08-4.80).

Conclusion

Hidden HypoCa at the initiation of dialysis was a significant risk factor of the combined outcome of all-cause mortality and CVD morbidity, independently of QTc prolongation, phosphate, and ALP, suggesting the importance of measuring iCa.