Supplementation of calcium, magnesium, phosphate, and potassium in critically ill patients: A multicenter cohort study.

Abstract

To investigate hospital-level variation in the supplementation of calcium, magnesium, phosphate, and potassium in critically ill patients. Retrospective cohort study. Premier Healthcare Database of inpatients from the USA. Adults (age ≥ 18 years) admitted to an intensive care unit (ICU) on hospital day 1 between October 1, 2022 and July 31, 2024, who had at least one calcium (total or ionized), magnesium, phosphate, or potassium level measured in an ICU between day 2 and 28. We excluded patients with renal failure, a pregnancy-related diagnosis, and intracranial bleeding on admission. Calcium, magnesium, phosphate, or potassium supplementation. We included 47,988 patients from 67 ICUs across 52 hospitals, totaling 167,621 patient-days with a measurement of one of the studied electrolytes. Median age was 64 years (interquartile range [IQR] 52-74) and 46% (22,057) were female. There were 38,621 patients (80.5%) with a minimum value below a lower limit of normal, and 33,626 (70.1%) patients who received supplementation. Across hospitals, the median (IQR) percentages receiving supplementation per day were: calcium 9.4% (6.7-12.2); magnesium 28.6% (22.6-35.0); phosphate 19.1% (15.9-23.2); potassium 28.9% (25.8-34.6). From a multilevel model, the median relative odds of supplementation, comparing any two hospitals, ranged from 1.51 (95% confidence interval [CI] 1.48-1.55) for potassium to 2.09 (95% CI 1.99-2.19) for magnesium. At most hospitals, there were no calcium or phosphate levels at which the percentage receiving supplementation exceeded 50%. At 75% of hospitals there was a magnesium level at which the percentage receiving magnesium supplementation was 50% or more (range: 1.5-2.1 mg/dL), and at 96% of hospitals there was an analogous potassium level (range: 3.3-3.9 mmol/L). Supplementation of calcium, magnesium, phosphate, or potassium is common in critically ill patients and varies across hospitals, suggesting a need for randomized trials to clarify optimal supplementation practices.