The incidence, characteristics, outcomes and associations of small short-term point-of-care creatinine increases in critically ill patients

Purpose: We assessed the incidence, characteristics, outcomes and associations of small, short-term point-of-care creatinine increases in critically ill patients. Methods: We prospectively identified the first episode of small (>1 μmol/L/h) short-term (3–4 h) point-of-care creatinine increase between two sequential arterial blood gas measurements. We followed patients for the subsequent development of Kidney Disease: Improving Global Outcomes (KDIGO) defined acute kidney injury (AKI) in the intensive care unit (ICU). Results: Of 387 patients, 279 (72.1%) developed an episode of small short-term point-of-care creatinine increase and 212 (54.8%) developed AKI. Such episodes occurred at a median of 5 (IQR 2–10) hours after ICU admission, while AKI occurred at a median of 15 (IQR 9–28) hours after admission. Patients with such episodes were more likely to be mechanically ventilated on admission (83.9 vs. 44.4%; p < .001) and had higher hospital mortality (10.9 vs. 3.7%, p = .03). Creatinine increase episodes had a sensitivity of 86% (95% CI 78–95) and specificity of 31% (95% CI 26–36) for subsequent AKI stages 2 and 3 in 24 h. Conclusions: Small, short-term point-of-care creatinine increase episodes are common. They are associated with illness severity, occur early, precede AKI by 10 h and are sensitive rather than specific markers of AKI.