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BACKGROUND Both balanced crystalloids and saline are used for intravenous fluid administration in critically ill adults, but it is not known which results in better clinical outcomes. METHODS In a pragmatic, cluster-randomized, multiple-crossover trial conducted in five intensive care units at an academic center, we assigned 15,802 adults to receive saline (0.9% sodium chloride) or balanced crystalloids (lactated Ringer’s solution or Plasma-Lyte A) according to the randomization of the unit to which they were admitted. The primary outcome was a major adverse kidney event within 30 days — a composite of death from any cause, new renal-replacement therapy, or persistent renal dysfunction (defined as an elevation of the creatinine level to ≥200% of baseline) — all censored at hospital discharge or 30 days, whichever occurred first. RESULTS Among the 7942 patients in the balanced-crystalloids group, 1139 (14.3%) had a major adverse kidney event, as compared with 1211 of 7860 patients (15.4%) in the saline group (marginal odds ratio, 0.91; 95% confidence interval [CI], 0.84 to 0.99; conditional odds ratio, 0.90; 95% CI, 0.82 to 0.99; P = 0.04). In-hospital mortality at 30 days was 10.3% in the balanced-crystalloids group and 11.1% in the saline group (P = 0.06). The incidence of new renal-replacement therapy was 2.5% and 2.9%, respectively (P = 0.08), and the incidence of persistent renal dysfunction was 6.4% and 6.6%, respectively (P = 0.60). CONCLUSIONS Among critically ill adults, the use of balanced crystalloids for intravenous fluid administration resulted in a lower rate of the composite outcome of death from any cause, new renal-replacement therapy, or persistent renal dysfunction than the use of saline. (Funded by the Vanderbilt Institute for Clinical and Translational Research and others; SMART-MED and SMART-SURG ClinicalTrials.gov numbers, NCT02444988 and NCT02547779.)

Objectives To test the hypothesis that, without diagnostic changes in serum creatinine, increased NGAL levels identify patients with subclinical acute kidney injury (AKI) and, therefore, worse prognosis. Background Neutrophil gelatinase-associated lipocalin (NGAL) detects subclinical AKI hours to days before increases in serum creatinine indicate manifest loss of renal function. Methods We analyzed pooled data from 2,322 patients with cardiorenal syndrome type 1 from ten prospective observational studies of NGAL. We used the terms NGAL(−) or NGAL(+) according to study-specific NGAL cut-off for optimal AKI prediction and the terms sCREA(−) or sCREA(+) to consensus diagnostic increases in serum creatinine defining AKI. A-priori-defined outcomes included need for renal replacement therapy (primary endpoint), hospital mortality, their combination and duration of stay in intensive care and in-hospital. Results Of study patients, 1,296 (55.8%) were NGAL(−)/sCREA(−), 445 (19.2%) NGAL(+)/sCREA(−), 107 (4.6%) NGAL(−)/sCREA(+) and 474 (20.4%) NGAL(+)/sCREA(+). According to the four study groups, there was a stepwise increase in subsequent renal replacement therapy initiation, (NGAL(−)/sCREA(−): 0.0015% vs. NGAL(+)/sCREA(−): 2.5% [odds ratio 16.4, 95% CI 3.6–76.9, P<0.001], NGAL(−)/sCREA(+): 7.5% and NGAL(−)/sCREA(−): 8.0%, respectively), hospital mortality (4.8%, 12.4%, 8.4%, 14.7%, respectively) and their combination (four-group comparisons: all P<0.001). There was a similar and consistent progressive increase in median number of intensive care and in-hospital days with increasing biomarker positivity: NGAL(−)/sCREA(−): 4.2 and 8.8 days; NGAL(+)/sCREA(−): 7.1 and 17.0 days; NGAL(−)/sCREA(+): 6.5 and 17.8 days; NGAL(+)/sCREA(+): 9.0 and 21.9 days; four-group comparisons: P=0.003 and P=0.040, respectively. Urine and plasma NGAL indicated a similar outcome pattern. Conclusions In the absence of diagnostic increases in serum creatinine, NGAL detects patients with subclinical AKI who have an increased risk of adverse outcomes. The concept and definition of AKI may need re-assessment.

BACKGROUND Comparative clinical effects of balanced crystalloids and saline are uncertain, particularly in noncritically ill patients cared for outside an intensive care unit (ICU). METHODS We conducted a single-center, pragmatic, multiple-crossover trial comparing balanced crystalloids (lactated Ringer’s solution or Plasma-Lyte A) with saline among adults who were treated with intravenous crystalloids in the emergency department and were subsequently hospitalized outside an ICU. The type of crystalloid that was administered in the emergency department was assigned to each patient on the basis of calendar month, with the entire emergency department crossing over between balanced crystalloids and saline monthly during the 16-month trial. The primary outcome was hospital-free days (days alive after discharge before day 28). Secondary outcomes included major adverse kidney events within 30 days — a composite of death from any cause, new renal-replacement therapy, or persistent renal dysfunction (defined as an elevation of the creatinine level to ≥200% of baseline) — all censored at hospital discharge or 30 days, whichever occurred first. RESULTS A total of 13,347 patients were enrolled, with a median crystalloid volume administered in the emergency department of 1079 ml and 88.3% of the patients exclusively receiving the assigned crystalloid. The number of hospital-free days did not differ between the balanced-crystalloids and saline groups (median, 25 days in each group; adjusted odds ratio with balanced crystalloids, 0.98; 95% confidence interval [CI], 0.92 to 1.04; P = 0.41). Balanced crystalloids resulted in a lower incidence of major adverse kidney events within 30 days than saline (4.7% vs. 5.6%; adjusted odds ratio, 0.82; 95% CI, 0.70 to 0.95; P = 0.01). CONCLUSIONS Among noncritically ill adults treated with intravenous fluids in the emergency department, there was no difference in hospital-free days between treatment with balanced crystalloids and treatment with saline.

Studies of acute kidney injury (AKI) commonly lack data on pre-admission renal function, often substituting an inpatient or imputed serum creatinine (SCr) as an estimate for “baseline” renal function. We examined the error introduced when applying methods to estimate “baseline” on AKI classification and mortality. Within a cohort of 4863 adults with a known outpatient baseline admitted to Vanderbilt University Hospital between 10/07 and 10/08, the following surrogates were studied: (1) an eGFR of 75 ml/min/1.73m2 as suggested by the Acute Dialysis Quality Initiative (ADQI), (2) a minimum inpatient SCr, and (3) the first admission SCr. We calculated AKI incidence and mortality rates using each surrogate, and assessed their ability to correctly classify AKI incidence and mortality compared to the most recent outpatient SCr between 7-365 days before admission. Using both imputed and minimum baseline SCr values inflated AKI incidence (38.3% and 35.9% vs. 25.5%; p<0.001), reflecting low specificities of 77% and 80%, respectively. In contrast, using an admission SCr baseline underestimated AKI incidence (13.7% vs. 25.5%, p<0.001), demonstrating a low sensitivity of 39%. Using any surrogate led to frequent misclassification of patient deaths as following AKI and differences for both in-hospital and 60-day mortality rates. In summary, commonly used surrogates for baseline SCr result in bi-directional misclassification of AKI incidence and prognosis in a hospitalized setting.

SummaryBackground and objectives Inaccurate determination of baseline kidney function can misclassify acute kidney injury (AKI) and affect the study of AKI-related outcomes. No consensus exists on how to optimally determine baseline kidney function when multiple preadmission creatinine measurements are available.Design, setting, participants, & measurements The accuracy of commonly used methods for estimating baseline serum creatinine was compared with that of a reference standard adjudicated by a panel of board-certified nephrologists in 379 patients with AKI or CKD admitted to a tertiary referral center.Results Agreement between estimating methods and the reference standard was highest when using creatinine values measured 7-365 days before admission. During this interval, the intraclass correlation coefficient (ICC) for the mean outpatient serum creatinine level (0.91 [95% confidence interval (CI), 0.88-0.92]) was higher than the most recent outpatient (ICC, 0.84 [95% CI, 0.80-0.88]; P,0.001) and the nadir outpatient (ICC, 0.83 [95% CI, 0.76-0.87; P,0.001) serum creatinine. Using the final creatinine value from a prior inpatient admission increased the ICC of the most recent outpatient creatinine method (0.88 [95% CI,). Performance of all methods declined or was unchanged when the time interval was broadened to 2 years or included serum creatinine measured within a week of admission. ConclusionsThe mean outpatient serum creatinine measured within a year of hospitalization most closely approximates nephrologist-adjudicated serum creatinine values.

Rationale: Saline is the intravenous fluid most commonly administered to critically ill adults, but it may be associated with acute kidney injury and death. Whether use of balanced crystalloids rather than saline affects patient outcomes remains unknown.Objectives: To pilot a cluster-randomized, multiple-crossover trial using software tools within the electronic health record to compare saline to balanced crystalloids.Methods: This was a cluster-randomized, multiple-crossover trial among 974 adults admitted to a tertiary medical intensive care unit from February 3, 2015 to May 31, 2015. The intravenous crystalloid used in the unit alternated monthly between saline (0.9% sodium chloride) and balanced crystalloids (lactated Ringer's solution or PlasmaLyte A). Enrollment, fluid delivery, and data collection were performed using software tools within the electronic health record. The primary outcome was the difference between study groups in the proportion of isotonic crystalloid administered that was saline. The secondary outcome was major adverse kidney events within 30 days (MAKE30), a composite of death, dialysis, or persistent renal dysfunction.Measurements and Main Results: Patients assigned to saline (n = 454) and balanced crystalloids (n = 520) were similar at baseline and received similar volumes of crystalloid by 30 days (median [interquartile range]: 1,424 ml [500-3,377] vs. 1,617 ml [500-3,628]; P = 0.40). Saline made up a larger proportion of the isotonic crystalloid given in the saline group than in the balanced crystalloid group (91% vs. 21%; P , 0.001). MAKE30 did not differ between groups (24.7% vs. 24.6%; P = 0.98).Conclusions: An electronic health record-embedded, clusterrandomized, multiple-crossover trial comparing saline with balanced crystalloids can produce well-balanced study groups and separation in crystalloid receipt.Clinical trial registered with www.clinicaltrials.gov (NCT 02345486).

Acute kidney injury (AKI), previously termed acute renal failure, is associated with increased hospital mortality, prolonged hospital stay, and is an important predictor of accelerated chronic kidney disease (CKD). Over the past 2 decades, dramatic rises in the incidence of AKI have been reported, particularly within the United States. The question arises as to whether these changes reflect an actual increase in disease incidence, or are potentially explained by the introduction of consensus definitions that rely on small standardized changes in serum creatinine, changes in hospital and clinician policies for coding and reimbursement, or increasingly available and more liberal use of dialysis. In this review, we explore the secular trends in AKI incidence in North America and Western Europe and its potential contributors.