title: Combination of two urinary biomarkers predicts acute kidney injury after adult cardiac surgery.
abstract: BACKGROUND
  Urinary L-type fatty acid-binding protein (L-FABP) has not been evaluated for adult post-cardiac surgery acute kidney injury (AKI) to date. This study was undertaken to evaluate a biomarker panel consisting of urinary L-FABP and N-acetyl-β-D-glucosaminidase (NAG), a more established urinary marker of kidney injury, for AKI diagnosis in adult post-cardiac surgery patients.
  
  
  METHODS
  This study prospectively evaluated 77 adult patients who underwent cardiac surgery at 2 general hospitals. Urinary L-FABP and NAG were measured before surgery, at intensive care unit arrival after surgery (0 hours), 4, and 12 hours after arrival. The AKI was diagnosed by the Acute Kidney Injury Network criteria.
  
  
  RESULTS
  Of 77 patients, 28 patients (36.4%) developed AKI after surgery. Urinary L-FABP and NAG were significantly increased. However, receiver operating characteristic (ROC) analysis revealed that the biomarkers' performance was statistically significant but limited for clinical translation (area under the curve of ROC [AUC-ROC] for L-FABP at 4 hours 0.72 and NAG 0.75). Urinary L-FABP showed high sensitivity and NAG detected AKI with high specificity. Therefore, we combined these 2 biomarkers, which revealed that this combination panel can detect AKI with higher accuracy than either biomarker measurement alone (AUC-ROC 0.81). Moreover, this biomarker panel improved AKI risk prediction significantly compared with predictions made using the clinical model alone.
  
  
  CONCLUSIONS
  When urinary L-FABP and NAG are combined, they can detect AKI adequately, even in a heterogeneous population of adult post-cardiac surgery AKI. Combining 2 markers with different sensitivity and specificity presents a reasonable strategy to improve the diagnostic performance of biomarkers.
authors.affiliation: Department of Nephrology and Endocrinology, The University of Tokyo, Tokyo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Katagiri
authors.forename: Kent
authors.initials: K
authors.lastname: Doi
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Honda
authors.forename: Kousuke
authors.initials: K
authors.lastname: Negishi
authors.forename: Toshiro
authors.initials: T
authors.lastname: Fujita
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Hisagi
authors.forename: Minoru
authors.initials: M
authors.lastname: Ono
authors.forename: Takehiro
authors.initials: T
authors.lastname: Matsubara
authors.forename: Naoki
authors.initials: N
authors.lastname: Yahagi
authors.forename: Masao
authors.initials: M
authors.lastname: Iwagami
authors.forename: Takayasu
authors.initials: T
authors.lastname: Ohtake
authors.forename: Shuzo
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sugaya
authors.forename: Eisei
authors.initials: E
authors.lastname: Noiri
mesh_terms: D000118:Acetylglucosaminidase / Q000652:urine*; D058186:Acute Kidney Injury / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000652:urine*; D000368:Aged; D019540:Area Under Curve; D015415:Biomarkers; D006348:Cardiac Surgical Procedures; D001026:Coronary Artery Bypass; D003404:Creatinine / Q000097:blood; D050556:Fatty Acid-Binding Proteins / Q000652:urine*; D005260:Female; D006351:Heart Valves / Q000601:surgery; D006801:Humans; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000097:blood / Q000453:epidemiology / Q000209:etiology / Q000652:urine*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012372:ROC Curve; D018570:Risk Assessment; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; C493319:FABP1 protein, human; D050556:Fatty Acid-Binding Proteins; D003404:Creatinine; D000118:Acetylglucosaminidase