© 2015 National Kidney Foundation, Inc. Background: In the general population, low serum magnesium levels are associated with poor outcomes and death. While limited data suggest that low baseline magnesium levels may be associated with higher mortality in hemodialysis (HD) patients, the impact of changes in magnesium levels over time is unknown. Study Design: We examined the association of time-varying serum magnesium levels with all-cause mortality using multivariable time-varying survival models adjusted for clinical characteristics and other time-varying laboratory measures. Setting & Participants: 9,359 maintenance HD patients treated in a large dialysis organization between 2007 and 2011. Predictor: Time-varying serum magnesium levels across 5 magnesium increments (<1.8, 1.8-<2.0, 2.0-<2.2, 2.2-<2.4, and ≥2.4. mg/dL). Outcome: All-cause mortality. Results: 2,636 individuals died over 5 years. Time-varying serum magnesium levels < 2.0. mg/dL were associated with higher mortality after adjustment for demographics and comorbid conditions, including hypertension, diabetes, and malignancies (reference: magnesium, 2.2-<2.4. mg/dL): adjusted HRs for serum magnesium level < 1.8 and 1.8 to <2.0. mg/dL were 1.39 (95% CI, 1.23-1.58; . P . <. 0.001) and 1.20 (95% CI, 1.06-1.36; . P =0.004), respectively. Some associations were attenuated to the null after incremental adjustment for laboratory test results, particularly serum albumin. However, among patients with serum albumin measurements, low albumin level (<3.5. g/dL) and magnesium level < 2.0. mg/dL were associated with an additional death risk (adjusted HR, 1.17; 95% CI, 1.05-1.31; . P =0.004), whereas patients with high serum albumin levels (≥3.5. g/dL) exhibited low death risk (adjusted HRs of 0.53 and 0.53 [. P . ≤. 0.001] for magnesium < 2.0 and ≥2.0. mg/dL, respectively; reference: albumin < 3.5. g/dL and magnesium ≥ 2.0. mg/dL). Limitations: Causality cannot be determined, and residual confounding cannot be excluded given the observational study design. Conclusions: Lower serum magnesium levels are associated with higher mortality in HD patients, including those with hypoalbuminemia. Interventional studies are warranted to examine whether correction of hypomagnesemia ameliorates adverse outcomes in this population.

Background In the general population, low serum magnesium levels are associated with poor outcomes and death. While limited data suggest that low baseline magnesium levels may be associated with higher mortality in hemodialysis (HD) patients, the impact of changes in magnesium levels over time is unknown. Study Design We examined the association of time-varying serum magnesium levels with all-cause mortality using multivariable time-varying survival models adjusted for clinical characteristics and other time-varying laboratory measures. Setting & Participants 9,359 maintenance HD patients treated in a large dialysis organization between 2007 and 2011. Predictor Time-varying serum magnesium levels across 5 magnesium increments (<1.8, 1.8-<2.0, 2.0-<2.2, 2.2-<2.4, and ≥2.4 mg/dL). Outcome All-cause mortality. Results 2,636 individuals died over 5 years. Time-varying serum magnesium levels < 2.0 mg/dL were associated with higher mortality after adjustment for demographics and comorbid conditions, including hypertension, diabetes, and malignancies (reference: magnesium, 2.2-<2.4 mg/dL): adjusted HRs for serum magnesium level < 1.8 and 1.8 to <2.0 mg/dL were 1.39 (95% CI, 1.23-1.58; P < 0.001) and 1.20 (95% CI, 1.06-1.36; P = 0.004), respectively. Some associations were attenuated to the null after incremental adjustment for laboratory test results, particularly serum albumin. However, among patients with serum albumin measurements, low albumin level (<3.5 g/dL) and magnesium level < 2.0 mg/dL were associated with an additional death risk (adjusted HR, 1.17; 95% CI, 1.05-1.31; P = 0.004), whereas patients with high serum albumin levels (≥3.5 g/dL) exhibited low death risk (adjusted HRs of 0.53 and 0.53 [P ≤ 0.001] for magnesium < 2.0 and ≥2.0 mg/dL, respectively; reference: albumin < 3.5 g/dL and magnesium ≥ 2.0 mg/dL). Limitations Causality cannot be determined, and residual confounding cannot be excluded given the observational study design. Conclusions Lower serum magnesium levels are associated with higher mortality in HD patients, including those with hypoalbuminemia. Interventional studies are warranted to examine whether correction of hypomagnesemia ameliorates adverse outcomes in this population.

The association between pretransplant serum albumin concentration and post-transplant outcomes in kidney transplant recipients is unclear. We hypothesized that in transplant-waitlisted hemodialysis patients, lower serum albumin concentrations are associated with worse post-transplant outcomes. Linking the 5-year patient data of a large dialysis organization (DaVita) to the Scientific Registry of Transplant Recipients, we identified 8961 hemodialysis patients who underwent first kidney transplantation. Mortality or graft failure and delayed graft function (DGF) risks were estimated by Cox regression (hazard ratio [HR]) and logistic regression (Odds ratio [OR]), respectively. Patients were 48 ± 13 years old and included 37% women and 27% diabetics. The higher pretransplant serum albumin was associated with lower mortality, graft failure and DGF risk even after multivariate adjustment for case-mix, malnutrition-inflammation complex and transplant related variable. Every 0.2 g/dL higher pretransplant serum albumin concentration was associated with 13% lower all-cause mortality (HR = 0.87 [95% confidence interval: 0.82-0.93]), 17% lower cardiovascular mortality (HR = 0.83[0.74-0.93]), 7% lower combined risk of death or graft failure (HR = 0.93[0.89-0.97]) and 4% lower DGF risk (OR = 0.96[0.93-0.99]). Hence, lower pretransplant serum albumin level is associated with worse post-transplant outcomes. Clinical trials to examine interventions to improve nutritional status in transplant-waitlisted hemodialysis patients and their impacts on post-transplant outcomes are indicated.