Patients
This study enrolled 37 ALL and 11 WT survivors who were treated between 2000 and 2013 at the Department of Paediatrics, Haematology and Oncology of the Medical University of Gdansk. The patients, from 7 to 18 years of age, were examined at least 5 years after the end of oncological treatment. The clinical study was performed during routine follow-ups. The study consisted of a patient history and a physical examination, including anthropometric measurements, triple BP measurements, and blood and urine sample collection.
Methods
The height, weight, and waist circumference were measured using standard techniques (Mensor WE 150, 2014).
During laboratory testing, we evaluated the morphology, serum creatinine, cystatin C, glucose, lipid profile and salusin β after an overnight fast.
Serum creatinine concentration was assayed using an enzymatic method (Alinityc Creatinine Reagent Kit Abbott). Serum cystatin C levels were detected by immunonephelometry (N Latex Cystatine C Siemens). The estimated glomerular filtration rate (eGFR) was calculated based on both the creatinine and cystatin C serum levels.
EGFR was measured indirectly using the original Schwartz, creatinine and BUN-based equation, and Filler formulas.
The Schwartz formula is defined as follows: GFR in mL/min/1.73 sq m = k x height of child in cm/serum creatinine concentration in mg/dL, where the constant k was defined using the published literature values of k=0.413 for children (10). Creatinine and BUN-based eGFR was calculated according to equation - 40.7(height/SCr)0.64(30/BUN)0.202 (11).
Additionally, the serum concentration of cystatin C was evaluated, and GFR was calculated according to the Filler formula: logGFR=1.962+[1.123xlog(1/cystatin C)] (12).
The plasma lipid profile was determined with electrophoresis (Hydragel 15 Lipo + Lp(a) Sebia). The concentration of salusin β was determined by an immunoenzymatic method using an Elisa set for salusin β (produced by Cloud-Clone Corp. 2018).
The International Diabetes Federation criteria were used to identify metabolic syndrome and central obesity (13).
Blood Pressure
Blood pressure (BP) was measured in every child in the study by an oscillometric method using a standard clinical sphygmomanometer (professional blood pressure monitor HBP-1100-E, OMRON HEALTHCARE Co., Ltd. Kyoto, Japan, 2014) according to guidelines and recommendation of the Polish Pediatric Nephrology Society (14). BP was measured three times in each patient. Mean values of the systolic and diastolic pressure were determined. The results were then compared to the reference values matched according to gender, age and height.
Statistical methods
The data are expressed as the mean, median and SDS values, and were compared with statistical tests, such as analysis of variance (ANOVA), the Mann-Whitney U test, the Kruskal-Wallis test with ranking and the chi-square test with the Yates correction. Analysis of the correlation between analysed parameters was evaluated using Spearman’s rank correlation coefficient.
P<0.05 was considered statistically significant.
The standard deviation score value was evaluated using the following formula:
SDS value = (observed value – mean value in referenced population)/SDS value in reference population.
For the reference population, we used the results of the OLAF research, which was performed among children from the Polish population aged from 7 to 18 years (15)(16).
Statistical analysis was performed using EPIINFO Ver. 7.1.1.14 software.