Comparative study of three methods of estimation of creatinine clearance in critically ill patients

Creatinine Clearance in Acute Brain Injury: A Comparison of Methods

BACKGROUND

Currently, the measurement of glomerular filtration rate is very complex and costly, so its daily evaluation is performed using endogenous markers, of which creatinine is the most frequently used. It allows the estimation of glomerular filtration rate by means of its clearance or by formulas based on its serum and urine concentration. Augmented renal clearance (ARC) is frequent among critically ill patients and is defined as creatinine clearance (CrCl) > 130 ml/min/1.73 m2. The aim of this study was to compare measured CrCl (MCC) and estimated CrCl obtained with the Cockcroft-Gault formula (CG), the Modification of Diet in Renal Disease Study equation (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration formula (CKD-EPI) in patients with severe traumatic brain injury and nontraumatic subarachnoid hemorrhage. The second aim was to assess the incidence of ARC in this population of neurocritical patients.

METHODS

This was a prospective, observational, single center study from a cohort of 74 patients admitted to the neurocritical intensive care unit due to traumatic brain injury or subarachnoid hemorrhage. Serum creatinine (at 7 a.m.) and a 6-h urine collection were analyzed, and CrCl was measured and estimated by using CG, MDRD, and CKD-EPI. The intraclass correlation coefficient (ICC) was evaluated for each pair, and Bland-Altman plots were used to assess clinical significance.

RESULTS

Among 74 patients, the median age was 53 (interquartile range [IQR] 36-65), and the median Glasgow Coma Scale score at admission was 6. The median MCC at admission was 176 (IQR 135-214). The medians of CG, MDRD and CKD-EPI were, respectively, 129 ml/min/1.73 m2 (IQR 95-176), 158 (IQR 115-202), and 116 (97-132). An ICC was applied to evaluate the correlation between MCC and estimated methods and showed a weak correlation between MCC and estimated CrCl obtained with the three different methods. The strongest ICC statistical correlation was found between MCC and MDRD, and the weakest correlation was found between MCC and CKD-EPI. Bland-Altman plots showed that differences between each pair were not clinically acceptable. ARC was present in 78% of measurements, using MCC. A weak correlation was observed between MCC and calculated CrCl. CG, MDRD, and CKD-EPI overestimated MCC when MCC ≤ 130 ml/min/1.73 m2 and underestimated it when MCC > 130 ml/min/1.73 m2.

CONCLUSIONS

In this population, there was a weak statistical correlation between measured and estimated methods. In patients with ARC, formulas underestimated MCC. MCC should probably be the preferred methodology for renal function assessment in the clinical setting to better adjust drug dosage and guarantee drug effectiveness.

Aminoglycoside-Related Nephrotoxicity and Ototoxicity in Clinical Practice: A Review of Pathophysiological Mechanism and Treatment Options

Aminoglycosides are a class of medications used to treat certain bacterial infections, specifically gram-negative aerobes. These drugs can be used alone as first-line treatments or in combination with other medications. There can be many different formulations of aminoglycosides including oral, inhalants, intravascular, intramuscular, or intraventricular. There are many distinctive types of aminoglycosides, and although they provide excellent coverage, they can have a wide variety of side effects. The most prevalent side effects of aminoglycosides are nephrotoxicity and ototoxicity. Aminoglycoside-induced nephrotoxicity is concerning because of the effects that abnormal creatinine levels can have on other drugs and the potential for neurotoxicity. Fortunately, changes in renal function are typically reversible. The kidney is affected by the drug's ability to enter the proximal tubule and cause a buildup of phospholipids in the lysosomes, inhibiting their function. Exposure to aminoglycosides in utero can result in permanent ototoxicity. The mechanism of ototoxicity is through the drug's ability to freely pass into hair cells and cause reactive oxygen species to damage the mitochondria, resulting in cell death. There is not a substantial amount of research regarding the prevention and treatment of adverse effects of aminoglycosides. Future research on the mediation or modulation of these pathophysiological processes would expand their usage in modern medicine.

Correlation of Measured and Estimated Creatinine Clearance in Hospitalized Elderly Patients: A Retrospective Cohort Study

Background: Accurate assessment of renal function is essential in hospitalized elderly patients. Few studies have examined the accuracy of Cockcroft-Gault (C-G) estimates of creatinine clearance (CrCl) compared with measured clearance in these patients. Objective: The objective of this study was to determine the correlation between C-G estimates of CrCl and measured CrCl in hospitalized elderly patients. Methods: This Institutional Review Board-approved, single-center retrospective observational cohort study included all patients who were 65 years and older admitted to our medical center in January to September 2018 with either an 8- or 24-hour urine collected during admission. The primary outcome was correlation, bias, and precision of C-G estimates of CrCl versus measured CrCl using Pearson correlation, Spearman linear regression, and Bland-Altman analysis. Outliers were determined using a cut-off of ±20%. Data are presented as median (interquartile range) or percentages. Results: A total of 108 urine collections from 90 unique patients were included in the study. The patients were 51% female, median age was 71 (68-77) years, and median body mass index was 26.6 (22.8-31) kg/m². Most collections were over 24 hours (66.7%), and 38% were performed while patients were in an intensive care unit. Median blood urea nitrogen (BUN) was 24.5 (17-36) mg/dL and median serum creatinine was 0.71 (0.55-1.09) mg/dL. The median C-G estimation was 75.4 (48.2-110.6) mL/min, and the median measured CrCl was 79.1 (38.1-99.5) mL/min, r ² = .56 (P < .001). Bland-Altman analysis showed large limits of agreement (-75.5-57.7 mL/min), with a bias of -8.9 and precision (standard deviation of bias) of 34 mL/min. Outliers were common, with 38% of C-G estimation values >120% of measured CrCl, and 18% of C-G estimates <80% of measured CrCl. Conclusions: Measured CrCl varied significantly from C-G estimates in hospitalized elderly patients. It is important to recognize characteristics of patients who may benefit from measurement of CrCl. Future studies should examine the impact of this variance on clinical outcomes.

Chronic kidney disease in patients with non-alcoholic fatty liver disease: What the Hepatologist should know?

The association of non-alcoholic fatty liver disease (NAFLD) with several other diseases has gained increased interest during the recent years. Among them, the association with chronic kidney disease (CKD) has emerged as an important one regarding both its prevalence and significance. The early recognition of this association is important for the prognosis of patients with NAFLD and CKD. Apart from early diagnosis, the accurate assessment of renal function is also crucial in the clinical practice of hepatologists. Several methods have been used in the literature for the evaluation of kidney function in patients with NAFLD up to now. In this respect, calculators (or formulas) for the estimation of Glomerular Filtration Rate (eGFR) and Albumin to Creatinine Ratio (ACR) are simple, practical and easily available methods for this purpose. The aim of this review is to report on the epidemiology and pathophysiology of the relationship between NAFLD and CKD and to describe the different methods of kidney function assessment in patients with NAFLD. The collection of all relevant data regarding this association will provide hepatologists with pertinent knowledge on this topic and allow them to use the most accurate methods for the assessment of kidney function in these patients in their clinical practice.

Role of an electronic antimicrobial alert system in intensive care in dosing errors and pharmacist workload

BACKGROUND

Critically ill patients are vulnerable to dosing errors. We developed an electronic Antimicrobial Dose alert based upon Creatinine clearance (ADC-alert), which gives daily antimicrobial dosing advice based upon the 24-h creatinine clearance (CLcr).

OBJECTIVE

Primary objective: to verify the correctness of the ADC-alert output and its benefit for the workload of the clinical pharmacist (CP). Secondary objective to compare the ADC-alert output between patients with normal and impaired CLcr.

SETTING

The 36-bed surgical and medical intensive care unit (ICU) of the Ghent University Hospital, Ghent, Belgium.

METHOD

In a single centre prospective observational 44-day study, prescriptions were reviewed by CP and compared with the ADC-alert output advice. CP workload was calculated with and without the use of the ADC-alert. Impaired renal function was defined as a CLcr < 50 mL/min for at least 1 day during antimicrobial treatment in the ICU or the need for renal replacement therapy (RRT).

MAIN OUTCOME MEASURES

Correct dosing recommendation by ADC-alert compared to CP review and time spent by CP with and without the ADC-alert.

RESULTS

A total of 87 patients (554 daily antimicrobial prescriptions; 435 patient days) were both screened by CP and ADC-alert. Renal function impairment occurred in 39 patients (44.8 %) with 12 patients requiring RRT. The ADC-alert gave a correct dosage advice in 483 prescriptions (87.2 %). The overall sensitivity was 77.3 %; specificity was 89.9 %. Use of the ADC-alert reduces CP workload with 76.5 % (average time spent per patient: 17 vs. 4 min). Patients with a CLcr < 50 mL/min less frequently received a correct recommendation than patients with normal CLcr (P = 0.001). This was due to configuration problems in dialysis patients.

CONCLUSION

We developed and evaluated an electronic alert system to generate dynamic antimicrobial dose adaptation based on the daily calculation of the 24-h CLcr of ICU patients. Its use led to substantial time savings for clinical pharmacists. However, the alert advice suffered from some developmental and other flaws. Despite resolving some of these shortcomings, bedside interpretation of the results and clinical judgement remain necessary.