Is hypophosphataemia an independent predictor of mortality in critically ill patients with bloodstream infection? A multicenter retrospective cohort study.

Background: Hypophosphataemia affects up to one-third of patients in the intensive care unit (ICU) and is particularly common during sepsis. Experimental data suggest that hypophosphataemia leads to an acquired dysfunction of leukocytes, thus promoting infections and increasing the risk of death during sepsis.

Objectives: The aim of our study was to investigate the association between hypophosphataemia and mortality in critically ill patients with a bloodstream infection (BSI).

Methods: We performed a retrospective study in three ICUs during an 18-month period. All adults with a BSI diagnosed in the ICU were eligible. Patients with and without hypophosphataemia, defined as phosphataemia below 0.8 mmol/L, were compared. A multivariate survival analysis using a Cox proportional hazard regression model was conducted to study the association between hypophosphataemia and 90-d mortality.

Results/findings: Among the 3783 patients admitted to the three participating ICUs within the 18-month study period, 203 met the inclusion criteria and 193 were analysed. Fifty-four patients had hypophosphataemia. After adjusting for confounders, hypophosphataemia was significantly associated with a twofold increased risk of 90-d mortality (hazard ratio = 2.10 [1.177-3.80], p = 0.013). This association is particularly strong in patients without shock.

Conclusions: Hypophosphataemia was independently associated with a twofold increase in 90-d mortality in ICU patients with a BSI. These results suggest that investigators and physicians should include phosphataemia as a predictor of the severity of BSIs. Further research is warranted to better understand this association and to determine the potential benefits of systematic monitoring of phosphataemia and phosphorus supplementation.

Clinical Trial Registration: NCT03529058.