Study design and aims
This single tertiary referral center cohort prospective study aimed to evaluate the role of renal Duplex ultrasonography as a possible method in early diagnosis and prediction of HRS in patients with liver cirrhosis.
Patients and recruitment
The study included 50 patients, aged 18 years or above, with Child C liver cirrhosis with documented normal baseline serum creatinine within 1 year prior to AKI. The patients were randomly selected among a group of patients presenting to the emergency room unit and admitted to the Department of Internal Medicine in Kasr Al Ainy Hospital during the period from January 2018 to July 2019.
Patients with confirmed pregnancy, prior kidney or liver transplant, known hypertensive patients, or other known causes of renal insufficiency such as advanced chronic kidney disease (CKD): baseline creatinine > 4.0 mg/dl, acute or chronic renal replacement therapy, diabetic nephropathy, glomerulonephritis, urinary tract obstruction, and urinary tract infection were excluded from the study.
We diagnosed HRS based on ICA-AKI criteria as mentioned before [7].
Methods
Patients with liver cirrhosis were randomly selected irrespective of the presenting symptom, hepatic status, and presence of complications. All these patients were subjected to thorough history taking and clinical examination including age, gender, comorbid diseases (diabetes, hypertension, and dyslipidemia), concomitant medications (renin-angiotensin-aldosterone system (RAAS) blockade and diuretics), and symptoms and signs of hepatic decompensation. Patients were evaluated using the Child-Pugh score and Model for End-Stage Liver Disease (MELD) score.
Laboratory investigations
Patients’ preparation: diuretics were stopped in all patients, at least 24 h before laboratory testing. Patients were advised to adopt a low sodium diet (less than 40 mmol/day).
A fresh 10-ml blood sample was collected daily. Laboratory tests were performed in Kasr Al Ainy Chemical Pathology Central Lab and included liver function tests, HCV antibody, and kidney function tests.
Creatinine was measured from samples collected as part of routine clinical care in our institution inpatients. Laboratory measurements were performed by personnel blinded to patient information.
Creatinine clearance (CLCr) was calculated by CrCl Cockroft Gault equation CCr = {((l 40–age) × weight)/(72 × SCr)}× 0.85 (if female). eGFR was calculated by the MDRD formula [9].
Abdominal ultrasound (US) and Duplex renal ultrasound were done using IU 22, Philips machine. A convex probe (C5-1 Hz) was used and US was done to all patients to confirm the presence of cirrhosis; to assess portal vein, hepatic artery and vein diameter, the presence or absence of portal vein thrombosis, and splenic size; to confirm the presence or absence of ascites and its degree; to confirm the presence of focal lesions of the liver and spleen; and to assess kidney size, volume, and echogenicity.
Duplex renal ultrasonography was also done to all patients by direct visualization of the renal arteries from the origin up to the interlobar arteries.
The renal resistive index (RRI) was evaluated along renal arteries up to interlobar arteries. RRI was calculated automatically by the machine as we measured the peak systolic and end-diastolic velocities of the different arteries.
We also determined the renal aortic ratio (RAR) which is the ratio of the PSV in the renal artery at the origin to the PSV in the aorta (at renal artery level) to exclude a diagnosis of renal artery stenosis.
The patients were followed up for 1 month by clinical evaluation of any deteriorating symptoms or lab profile.
Statistical methodology
The analysis of our data was performed using IBM computer exploiting SPSS (Statistical Program for Social Science version 12) as follows: description of quantitative variables as mean, SD, and range. Description of qualitative variables was done as number and percentage. A chi-square test was used to compare qualitative variables between groups. An unpaired t-test was used to compare quantitative variables, in parametric data (SD<50% mean). The Mann-Whitney-Willcoxon U test was used in nonparametric data instead of an unpaired t-test. One-way ANOVA (analysis of variance) was used to compare more than two groups as regard quantitative variable. The Kruskal-Wallis test was used instead of the ANOVA test in non-parametric data SD>50% mean. Spearman correlation test was used to rank variables versus each other positively or inversely. Logistic regression analysis was used to find out the significant independent predictors of the dependent variable using the backward likelihood ratio technique. In this context, p-value > 0.05 was considered as insignificant, p< 0.05 as significant, and p < 0.01 as highly significant.
Ethical consideration
The study was approved by the institution ethical committee and form review board of Kasr Al Ainy Hospital. Oral and written informed consents were obtained from all subjects or from their eligible relatives.
The medical record profession has its own code of ethics which applies to all medical record practitioners. Confidentiality of data, safe data storage, and privacy rights are respected by all who handle patient information. Data was coded and patient names or identity was not appearing in any of data collection forms or during statistical analysis.