Phosphate Supplementation and Target Serum Levels in Sepsis: Impact on Patient Outcomes

Abstract Objectives There is no clinical protocol for the management of serum inorganic phosphate (Pi) in critically ill patients until now. We aimed to assess the effect of phosphate supplementation on the in-hospital mortality of septic patients with hypophosphatemia and explore the optimal threshold level of serum Pi in patients with sepsis. Methods A retrospective analysis of septic patients selected from the Medical Information Mart for Intensive Care (MIMIC)-IV database was carried out. Adjusted OR was used to examine the impact of phosphate supplementation on the hospital mortality. Serum Pi levels were divided into 6 bands. Multivariable logistic regression model was established for each band to investigate the optimal threshold Pi level. Results 8067 admissions were enrolled and 88967 recorded Pi measurements were collected. The incidence of hypophosphatemia was 26.4% in septic patients. After adjusting for confounding factors, it was found that with phosphate supplemented, mortality tended to increase in septic patients with hypophosphatemia, though not significantly (OR 1.28, 95%CI 0.98–1.66, p = 0.33 in Model 2). The regression models indicated that the hospital mortality benefit accrues within the serum Pi level of 1.5–3.5 mg/dl. Conclusions Our findings suggest that phosphate supplementation without a standard protocol did not improve the prognosis of septic patients with hypophosphatemia. Target serum Pi level appears to be the dominant factor influencing the risk of hospital mortality. The optimal level was lower than the normal range in septic population in our study. Randomized studies are needed to improve the knowledge of management for serum Pi in septic patients.