Divergent associations of phosphate levels with organ failure between ICU and non-ICU populations with acute pancreatitis.

BACKGROUND

Acute pancreatitis lacks reliable early predictors of disease severity. Serum phosphate has been shown to be associated with the severity and mortality of acute pancreatitis, but its utility is uncertain.

OBJECTIVE

To assess the association between serum phosphate and organ failure in AP, and determine if it differs between ICU and non-ICU settings.

METHODS

Retrospective cohort study using MIMIC-IV (n = 2,973) and eICU databases (n = 216). The primary outcome was organ failure (acute kidney injury, respiratory failure, or shock). Secondary outcomes included hypotension (SBP < 90 mmHg) and mechanical ventilation. Logistic regression was performed, stratified by ICU admission, with analyses progressively adjusted for demographics and key biochemical covariates.

RESULTS

Among non-ICU patients, serum phosphate showed a significant inverse association with organ failure (adjusted OR: 0.67, 95%CI: 0.53-0.85, P = 0.001). In ICU patients, phosphate was not associated with the primary outcome. However, in the ICU setting, phosphate levels demonstrated significant positive associations with both hypotension and the need for mechanical ventilation. These associations remained significant after multiple testing corrections and were consistent across both independent databases (P < 0.05).

CONCLUSION

The association between serum phosphate and clinical outcomes in AP patients without chronic kidney disease is context-dependent. Hypophosphatemia is associated with organ failure in non-ICU patients, while in critically ill ICU patients, hyperphosphatemia is linked to severe respiratory/circulatory compromise. The association between serum phosphate and clinical outcomes varies with disease severity, necessitating consideration of clinical setting.