title: Serum uric acid level as a risk factor for acute kidney injury in hospitalized patients: a retrospective database analysis using the integrated medical information system at Kochi Medical School hospital.
abstract: OBJECTIVE
  Recent studies have shown that both low and high levels of serum uric acid (SUA) before cardiovascular surgery are independent risk factors for postoperative acute kidney injury (AKI). However, these studies were limited by their small sample sizes. Here, we investigated the association between SUA levels and AKI by performing a retrospective database analysis of almost 30 years of data from 81,770 hospitalized patients.
  Hospitalized patients aged ≥18 years were retrospectively enrolled. AKI was diagnosed according to the Kidney Disease: Improving Global Outcomes 2012 Clinical Practice Guideline (KDIGO) criteria. Multivariate logistic regression analyses were performed to investigate the independent association between SUA levels and the incidence of AKI. SUA levels were treated as categorical variables because the relationship between SUA and the incidence of AKI has been suggested to be J-shaped or U-shaped. In addition to stratified SUA levels, we considered kidney function and related comorbidities, medications, and procedures performed prior to AKI onset as possible confounding risk factors.
  
  
  RESULTS
  The final study cohort included 59,219 adult patients. Adjusted odds ratios of AKI incidence were higher in both the high- and low-SUA strata. Odds ratios tended to become larger in the higher range of SUA levels in women than in men. Additionally, this study showed that AKI risk was elevated in patients with SUA levels ≤7 mg/dL. An SUA level >7 mg/dL is considered the point of initiation of uric acid crystallization.
  
  
  CONCLUSIONS
  SUA level could be an independent risk factor for AKI development in hospitalized patients. Additionally, our results might suggest that intervention to lower SUA levels is necessary, even in cases of moderate elevation that does not warrant hyperuricemia treatment. Results also showed that SUA levels that require attention are lower for women than for men.
authors.affiliation: Center for Innovative and Translational Medicine, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Otomo
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan. horinott@yahoo.co.jp.
authors.forename: Taro
authors.initials: T
authors.lastname: Horino
authors.affiliation: Center for Innovative and Translational Medicine, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Miki
authors.affiliation: Center of Medical Information Science, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kataoka
authors.affiliation: Center of Medical Information Science, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hatakeyama
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Tatsuki
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Kazu
authors.initials: K
authors.lastname: Hamada-Ode
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Shimamura
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Ogata
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Inoue
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Taniguchi
authors.affiliation: Department of Endocrinology, Metabolism and Nephrology, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Kochi, 783-8505, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Terada
authors.affiliation: Center of Medical Information Science, Kochi Medical School, Kochi University, Kohasu, Oko-cho, Nankoku, Japan.
authors.forename: Yoshiyasu
authors.initials: Y
authors.lastname: Okuhara
mesh_terms: D058186:Acute Kidney Injury / Q000097:blood* / Q000453:epidemiology; D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D066275:Health Information Exchange; D006801:Humans; D007297:Inpatients / Q000706:statistics & numerical data; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D014527:Uric Acid / Q000097:blood*
chemical_list: D015415:Biomarkers; D014527:Uric Acid
keywords: AKI; Acute kidney injury; Hyperuricemia; Hypouricemia; Medical database analysis