Urinary TIMP-2·IGFBP7: meta-analysis supports early detection of AKI

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  • Urinary tissue inhibitor of metalloproteinase-2 (TIMP-2) and insulin-like growth factor binding protein 7 (IGFBP7) may represent a reliable biomarker for early detection of acute kidney injury (AKI).

Why this matters

  • The test is relatively new, and its clinical utility remains unclear.

Study design

  • Systematic review and meta-analysis of 9 studies (n=1886); 4 in cardiac surgery patients, 4 in critically ill patients, and 1 in emergency department patients.
  • All defined AKI based on Kidney Disease: Improving Global Outcomes criteria; urinary TIMP-2·IGFBP7 measured using NephroCheck.
  • Funding: None.

Key results

  • TIMP-2·IGFBP7 diagnostic accuracy was fair, with a pooled sensitivity and specificity of 0.83 (95% CI, 0.75-0.89; I2, 79.87%) and 0.72 (95% CI, 0.56-0.84; I2, 95.38%), respectively; area under the summary receiver operating characteristic (SROC) curve was 0.86 (95% CI, 0.82-0.88).
  • Sensitivity and specificity for stage ≥2 AKI were 0.92 (95% CI, 0.81-0.96; I2, 73.45%) and 0.63 (95% CI, 0.49-0.74; I2, 94.70%), respectively; area under SROC curve was 0.88 (95% CI, 0.85-0.91).
  • Significant publication bias observed (P=.04).


  • 3 studies had high-risk bias (1 in patient selection; 2 in flow/timing).
  • Significant heterogeneity.
  • Most of the patients were associated with 2 authors.
  • Key studies excluded because of inability to extract a 2×2 contingency table.