Serum Magnesium Levels and Hospitalization and Mortality in Incident Peritoneal Dialysis Patients: A Cohort Study

Abstract

Background

Prior studies have shown the association of low serum magnesium with adverse health outcomes in patients undergoing hemodialysis. There is a paucity of such studies in patients undergoing peritoneal dialysis (PD).

Study Design

Cohort Study.

Setting & Participants

10,692 patients treated with PD January 1, 2007–December 31, 2011 in facilities operated by a single large dialysis organization in the United States.

Predictor

Baseline serum magnesium levels, examined as five categories (<1.8, 1.8–<2.0, 2.0–<2.2 [reference], 2.2–<2.4, and ≥2.4 mg/dL).

Outcomes

Time to first hospitalization and time to death using competing risks regression models.

Results

The distribution of baseline serum magnesium levels in the cohort were < 1.8 mg/dl: 1928 (18%); 1.8–<2.0 mg/dl: 2204 (21%); 2.0–<2.2 mg/dl: 2765 (26%); 2.2–<2.4 mg/dl: 1765 (16%); and ≥ 2.4 mg/dl: 2030 (19%). Of the 10,692 patients, 6465 (60%) were hospitalized at least once and 1392 (13%) died during follow-up (median, 13; IQR, 7–23 months). Baseline serum magnesium <1.8 mg/dL was associated with higher risk for hospitalization and all-cause mortality after adjustment for demographic and clinical characteristics (adjusted HRs of 1.23 [95% CI, 1.14–1.33] and 1.21 [95% CI, 1.03–1.42], respectively). The higher risk for hospitalization persisted upon adjustment for laboratory variables while that for all-cause mortality was attenuated to a non-significant level. The greatest risk for hospitalization was in patients with low serum albumin (< 3.5 g/dl; p for interaction < 0.001).

Limitations

Possibility of residual confounding by unmeasured variables cannot be excluded.

Conclusions

Lower serum magnesium levels may be associated with higher risk of hospitalization in incident PD patients, particularly among those with hypoalbuminemia. Additional studies are needed to confirm these findings and investigate whether correction of hypomagnesemia reduces these risks.