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

Abstract

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.

Keywords: Acute kidney injury; Adult; Creatinine; Critical illness; Intensive care unit; Point-of-care testing.