Association between blood phosphorus level and clinical outcomes in critically ill patients: A systematic review and...

Phosphorus is essential for biological functions and disturbances in its levels can cause phosphorus imbalance, which has ben linked to important clinical outcomes. The study aims to investigate the relationship between blood phosphorus levels and key outcomes, including mortality, intensive care unit stay, and mechanical ventilation duration.

This systematic review and meta-analysis was conducted in accordance with Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. A comprehensive search was performed in PubMed, Web of Science, Scopus, and Embase up to October 2024. Studies involving adult intensive care unit patients with reported blood phosphorus levels and associated clinical outcomes were included. Risk of bias was assessed using the ROBINS-I tool.

A total of 43 observational studies were included. Hypophosphatemia was not significantly linked to intensive care unit or hospital mortality but was associated with prolonged intensive care unit stay (+1.53 days), and mechanical ventilation duration (+1.54 days). Hyperphosphatemia was significantly associated with increased intensive care unit mortality (RR: 1.21, 95% CI: 1.13, 1.29; P < 0.001; n = 13) and hospital mortality (RR: 2.10, 95% CI: 1.49, 2.95; P < 0.001; n = 8), longer intensive care unit stay (+0.80 days), and extended mechanical ventilation (+4.23 days). Potential sources of heterogeneity included the use of renal replacement therapy among patients in the intensive care unit length of stay analysis and the timing of phosphorus measurement in the intensive care unit mortality analysis in hypophosphatemia. Also, patients receiving renal replacement therapy emerged as a potential source of heterogeneity in the analysis of hospital mortality in hyperphosphatemia. The evidence quality was low to very low, with high heterogeneity across studies.

Pooled heterogeneous data from available low-quality evidence suggests an association of phosphate abnormalities with longer duration of mechanical ventilation, increased intensive care unit and hospital stays, and hyperphosphatemia with mortality. These findings could underline the need for regular phosphorus monitoring and targeted interventions in the intensive care unit.