Table 1. The search terms used in systematic review.

Frame	Search terms Diagnostic accuracy of NGAL versus cystatin C in contrast-induced nephropathy
Population	(contrast media) or (contrast agent) or (contrast materials) or (contrast material) or (radiocontrast media) or (radiocontrast agent) or (radiocontrast agents) or (radiopaque media)
Index tests	Lipocalin-2 or Lipocalin2 or (NGAL protein) or (oncogene 24p3 protein) or (siderocalin protein) or (neutrophil Gelatinase-Associated Lipocalin) or (neutrophil Gelatinase Associated Lipocalin) or (Lipocalin-2 protein) or (Lipocalin 2 protein)
Comparator	(Cystatin C) or (post-gamma-Globulin) or (post gamma Globulin) or (Neuroendocrine Basic Polypeptide) or (Cystatin 3) or (gamma-Trace) or (gamma Trace)
Outcome	(acute kidney injury) or (acute kidney injuries) or (acute renal injury) or (acute renal injuries) or (acute renal insufficiency) or (acute renal insufficiencies) or (acute kidney insufficiency) or (acute kidney failure) or (acute kidney failures) or (acute renal failure) or (acute renal failures) or (kidney disease) or (kidney diseases) or nephropathy