OBJECTIVES: Acute kidney injury (AKI) occurs in 30–70% of critically ill patients, and is associated with substantial morbidity and mortality. AKI is conventionally diagnosed by elevated serum creatinine and decreased urine output, which are identified at the onset of kidney damage. An innovative urinary assay based on the tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor-binding protein 7 (IGFBP7) biomarkers permits AKI risk stratification before kidney damage occurs. In this study we compared the costs of [TIMP-2]·[IGFBP7]-guided early intervention versus standard of care (SoC) in critically ill patients.

METHODS: A decision tree model was developed. In the SoC arm, all patients received a nephroprotective bundle upon ICU admission. In comparison, only patients at high-risk of AKI based on [TIMP-2]·[IGFBP7] testing received the nephroprotective bundle. In a second analysis, patients in the SoC arm only received the nephroprotective bundle upon onset of AKI. Sensitivity (92%) and specificity (46%) of [TIMP-2]·[IGFBP7] testing was taken from Bihorac et al. (2014); AKI incidence and length of stay were calculated from Hoste et al. (2015). The model took a UK NHS perspective, using NHS reference costs and microcosting.

RESULTS: Total expected costs associated with [TIMP-2]·[IGFBP7]-guided implementation of the nephroprotective bundle were £12,291, compared to £12,314 using SoC, resulting in cost savings of £23 per patient. In the second analysis without routine nephroprotective care, implementation of [TIMP-2]·[IGFBP7]-testing resulted in cost savings of £675 per patient.

CONCLUSIONS: The addition of [TIMP-2]·[IGFBP7]-testing to the critical care pathway permits early AKI risk assessment to guide nephroprotective intervention, avoiding unnecessary treatment in patients not at risk of AKI, or preventing AKI cases. Implementation of [TIMP-2]·[IGFBP7] testing in the NHS is therefore expected to result in cost savings. The costing assumptions for the bundle components were conservative, and as such the realised cost savings may be even greater in clinical practice.