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JAMA Surg. 2018 Sep 1;153(9):e182009. doi: 10.1001/jamasurg.2018.2009. Epub 2018 Sep 19.

Association Between Preoperative Proteinuria and Postoperative Acute Kidney Injury and Readmission.

Author information

1
Birmingham and Tuscaloosa Health Services Research and Development Unit, Birmingham Veterans Affairs Medical Center, Birmingham, Alabama.
2
Department of Surgery, University of Alabama at Birmingham.
3
Center for Healthcare Organization and Implementation Research, Veterans Affairs Boston Healthcare System, Boston, Massachusetts.
4
Department of Surgery, Boston University School of Medicine, Boston, Massachusetts.
5
School of Medicine, Harvard University, Boston, Massachusetts.
6
Veterans Affairs Palo Alto Healthcare System, Palo Alto, California.
7
Department of Surgery, Stanford University, Stanford, California.
8
Milwaukee Veterans Affairs Medical Center, Milwaukee, Wisconsin.
9
Department of Medicine, Medical College of Wisconsin, Milwaukee.
10
Department of Surgery, Medical College of Wisconsin, Milwaukee.
11
Veterans Affairs Central Western Massachusetts Health Care System, Leeds.
12
Center for Applied Health Research, Baylor Scott and White Health, Temple, Texas.
13
Department of Medicine, Texas A&M Health Science Center, Temple.

Abstract

Importance:

Proteinuria indicates renal dysfunction and is a risk factor for morbidity among medical patients, but less is understood among surgical populations. There is a paucity of studies investigating how preoperative proteinuria is associated with surgical outcomes, including postoperative acute kidney injury (AKI) and readmission.

Objective:

To assess preoperative urine protein levels as a biomarker for adverse surgical outcomes.

Design, Setting, and Participants:

A retrospective, population-based study was conducted in a cohort of patients with and without known preoperative renal dysfunction undergoing elective inpatient surgery performed at 119 Veterans Affairs facilities from October 1, 2007, to September 30, 2014. Data analysis was conducted from April 4 to December 1, 2016. Preoperative dialysis, septic, cardiac, ophthalmology, transplantation, and urologic cases were excluded.

Exposures:

Preoperative proteinuria as assessed by urinalysis using the closest value within 6 months of surgery: negative (0 mg/dL), trace (15-29 mg/dL), 1+ (30-100 mg/dL), 2+ (101-300 mg/dL), 3+ (301-1000 mg/dL), and 4+ (>1000 mg/dL).

Main Outcomes and Measures:

Primary outcome was postoperative predischarge AKI and 30-day postdischarge unplanned readmission. Secondary outcomes included any 30-day postoperative outcome.

Results:

Of 346 676 surgeries, 153 767 met inclusion criteria, with the majority including orthopedic (37%), general (29%), and vascular procedures (14%). Evidence of proteinuria was shown in 43.8% of the population (trace: 20.6%, 1+: 16.0%, 2+: 5.5%, 3+: 1.6%) with 20.4%, 14.9%, 4.3%, and 0.9%, respectively, of the patients having a normal preoperative estimated glomerular filtration rate (eGFR). In unadjusted analysis, preoperative proteinuria was significantly associated with postoperative AKI (negative: 8.6%, trace: 12%, 1+: 14.5%, 2+: 21.2%, 3+: 27.6%; P < .001) and readmission (9.3%, 11.3%, 13.3%, 15.8%, 17.5%, respectively, P < .001). After adjustment, preoperative proteinuria was associated with postoperative AKI in a dose-dependent relationship (trace: odds ratio [OR], 1.2; 95% CI, 1.1-1.3, to 3+: OR, 2.0; 95% CI, 1.8-2.2) and 30-day unplanned readmission (trace: OR, 1.0; 95% CI, 1.0-1.1, to 3+: OR, 1.3; 95% CI, 1.1-1.4). Preoperative proteinuria was associated with AKI independent of eGFR.

Conclusions and Relevance:

Proteinuria was associated with postoperative AKI and 30-day unplanned readmission independent of preoperative eGFR. Simple urine assessment for proteinuria may identify patients at higher risk of AKI and readmission to guide perioperative management.

PMID:
29971429
PMCID:
PMC6233648
[Available on 2019-07-03]
DOI:
10.1001/jamasurg.2018.2009

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