Fig. 5

Association between early serum phosphate as a continuous variable and risk of ICU mortality of critically ill elderly patients. The analysis used a restricted cubic spline model with adjustment for age, SOFA score, Charlson index, respiratory rate, heart rate, mean arterial pressure, SpO₂, WBC count, hemoglobin, urea, anion gap, AKI, and dialysis treatment. The reference (hazard ratio = 1, horizontal dotted line) was a serum phosphate of 4.3 mg/dL (vertical dotted line)