Study design
This study is a retrospective cohort study in which all the cases who underwent Cohen and Gil-Vernet surgeries were recruited from 2010 to 2017. The protocol of this study was approved by the ethics committee of Iran university of medical sciences (Code of Ethics IR.IUMS.REC.1400.001) and it is consistent with the Helsinki's Declaration. Written informed consent was obtained from the parents or guardians of the participants.
Study participants
All children at the age less than 15 years old, with primary high-grade VUR (grade IV or V), and mild to moderate VUR with breakthrough infections who went under surgical re-implantation recruited. Patients with secondary urinary reflux to neurogenic bladder and urinary system malformations are excluded. The indications for surgery were poor medical compliance, recurrent of UTI while receiving prophylaxis antibiotics, worsening of kidney function and appearing new scars.
Study variables
Demographic data, history of antenatal and postnatal hydronephrosis , urinary tract infection, age at the onset of urinary tract infection, time interval between diagnosis of urinary tract infection and detection of VUR, resistance to urinary tract infection (Children undergoing drug prophylaxis unfortunately developed urinary tract infections) , DRNC or VCUG before and after surgery , DMSA before surgery, blood pressure, proteinuria ( random urine Pr/Cr : in 6 month to 2 years old and older than 2 years old > 100 mg/mmol ) (15), method of surgery, date of surgery, last ultrasound findings prior to surgery, creatinine, and eGFR calculate by Schwartz formula (16, 17) that based on the last creatinine recorded from the patient before surgery.
Schwartz formula: eGFR = k x (height in cm) ÷ serum Cr
In this study, hydronephrosis was defined as dilation of renal pelvis and/or calyces which diagnosed by ultrasonography during pregnancy screening or after birth examinations(18). A child of infant was considered to have UTI when the urine culture was positive alongside pyuria and/or bacteriuria(19). For the purpose of urine collection in infants, a voided urine specimen can be collected by attaching a sterile bag to the perineum. In children the clean-catch midstream method was implemented (19). According to the 2012 Italian Society of Pediatric Nephrology, urinary tract infections was defined as Criteria Colony count (CFUs/ml) based on the method of collection in the study as follows: Catheterization > 104 , Clean voided urine>105 , Urine bag>105 (20). A nuclear medicine specialist was responsible to perform all DMSA scan. Renal scars were classified according to standard classification. The types were classified as type 1: no more than two scars, type 2: more than two scars with some normal parenchyma between them, type 3: generalized damage to the whole kidney and type 4: end stage “shrunken kidney”(21). The HTN was defined as having three elevated systolic or diastolic blood pressure readings for the subject’s age, height, and sex. children younger than 13 years hypertension is defined as blood pressure in the 95th percentile or higher and older than 13 years old hypertension is defined as blood pressure of 130/80 mm Hg or higher (22).
After gathering primary information, we performed a telephone-based interview with the all-patient parents and asked about postoperative enuresis, incidence and severity of UTI. In this study and according to the American pediatric academy, the enuresis was defined as the involuntary wetting of clothes or bedding by urine during the daytime or nighttime (23). Parents were asked to report, tests and DRNCs they had 3 months after the surgery and provide regarded documents. Diagnostic method for some of these patients were DRNC, while for some others it was VCUG. Due to the fact that these two methods are reported in different ways and to assimilate information, grade 1 and 2 reflux in VCUG method is considered as mild reflux in DRNC, grade 3 reflux in VCUG as moderate reflux in DRNC and grade 4 and 5 reflux in VCUG is considered as severe reflux in DRNC method in our interpretation(24) .
Statistical analysis
All statistical analysis was performed by using SPSS software version 22. The mean and standard deviation were used to report quantitative variables. For the qualitative variables frequency and regarded percentage was used. Normal distribution of variables was assessed using Kolmogorov-Smirnov test. To compare quantitative variables before and after the surgery, pair t-test was used assuming the normality and Wilcoxon test was used otherwise. To compare two independent surgical methods in parametric instances the independent t-test is used and Mann-Whitney is used in non-parametric situation. Analysis of variance (ANOVA) was used to compare more than two groups. If the distribution of variables is not normal, non-parametric Kruskal-Walli’s test was implemented. Chi-square test was employed for statistical analysis of qualitative variables. P values less than 0.05 was considered as a significant level of statistical tests.