Epidemiology of hypophosphatemia in critical illness: A multicentre, retrospective cohort study

INTRODUCTION: Hypophosphatemia is common in critically ill patients. We have described the epidemiology of hypophosphatemia in patients admitted to the Intensive Care Units. METHODS: ): "None" (PO4: ≥0.81 mmol/L, "Mild" (PO4: ≥0.50 & <0.81 mmol/L) "Moderate" (PO4: ≥0.30 & <0.50 mmol/L) and "Severe" (PO4: <0.30 mmol/L). A mixed-effect logistic regression model, including hospital as a random effect, was developed to examine factors associated with 90-day case fatality. RESULTS: Of the 89,776 patients admitted, 68,699 patients were included in this study, with 23,485 (34.2%) having hypophosphatemia with onset mostly on Day 2 of ICU admission and correcting to normal 3 days after hypophosphatemia was identified. There was substantial variation among participating ICUs in phosphate replacement; the threshold, and the route by which it was replaced. Day-90 case fatality increased with severity of hypophosphatemia (None: 3974 (8.8%), Mild: 2306 (11%), Moderate: 377 (14%); Severe: 108 (21%) (p < 0.001)). Multivariable regression analysis showed that compared to those without hypophosphatemia, patients with moderate (odds ratio (OR) 1.24; 95% confidence intervals (CI) 1.07-1.44; p = 0.004) or severe (OR 1.49; 95% CI 1.13-1.97; p = 0.005) hypophosphatemia had increased risk of 90-day case fatality. CONCLUSION: Hypophosphatemia was common, and mostly occurred on day 2 with early correction of serum phosphate. Phosphate replacement practices were variable among ICUs. Moderate and severe hypophosphatemia was associated with increased 90-day case fatality.