Comparison of staging, shear wave elastography fibrosis scores, resistive index and fibrosis markers in chronic renal failure

Introduction: Chronic kidney disease (CKD) is a global health problem. Approximately one out of every 9 to 10 people is thought to have CKD. Early diagnosis and treatment are known to slow down the progression. Renal fibrosis has an important role in CKD pathophysiology and the loss of kidney function. Detection of renal fibrosis is thought to be useful in the early diagnosis of CKD, in determining its prognosis and in developing new treatment options. Fibrosis diagnosis and its grade can be determined by renal biopsy, but it is not practical to apply it to all patients since it is an invasive and difficult method. Therefore, research is being conducted to find noninvasive methods that can be used to detect renal fibrosis. In our study, we aimed to determine the relationship between the blood levels of renal fibrosis markers Transforming Growth Factor-Beta1 (TGF-β1), Interleukin-6 (IL-6), Apelin-12, inflammation marker high sensitivite C-reactive protein (hs-CRP), renal doppler ultrasonography (US) and rezistivity index (RI) and between the renal shear-wave elastography and the renal fibrosis scores. We hope to contribute to the detection of noninvasive methods in diagnosis of renal fibrosis. Materials and Method: The study was designed as a prospective case-control study. Eighty eight patients who referred to Düzce University Training and Research Hospital Internal Medicine or Nephrology clinic between February 2017 and July 2017, that are older than 18-years and with stage 2, 3, 4, 5 CKD according to Kidney Disease Improving Global Outcomes criteria (KDIGO), were included in the study. Twenty patients who were found to have one of the exclusion criteria were excluded from the study. The study was completed with 68 patients and a control group of 19 people. Eight patients were stage 2, 27 patients were stage 3, 20 patients were stage 4 and 13 patients were stage 5 CKD in the patient group. Age, gender, comorbidities and body mass index (BMI) of subjects were recorded, blood samples were taken and shear-wave elastography and renal doppler US were measured. Results: A total of 87 people were included in the study, including 68 patients and 19 healthy subjects. While the female to male ratio of the participants was similar (p: 0.752), mean age of the patient group was found higher (p<0.001). In our study, hs-CRP, IL-6, Apelin-12 levels were significantly higher in the patient group (p:0.001, p:0.004 and p:0.009, respectively). Although Apelin-12 was measured at higher values with increasing CKD stages(p: 0.047), this correlation was not found in hs-CRP and IL-6 (p: 0.374 and p: 0.224, respectively). TGF-β1 values were higher in the patient group than the control group, but it was not found statistically significant (p: 0.313). There was no statistically significant difference between the CKD stages (p: 0.196). In subgroup analyzes, Apelin-12 levels were significantly lower in the diabetic patient group than in the non-diabetic patient group (p: 0.009). RI was found to be significantly higher in patient group than control group (p <0.001) and found to be increasing with increasing CKD stages, which was also statistically significant (p: 0.015). For the elasticity score, even though there is a difference between the patient-control groups and the CKD stages, it was not found to be statistically significant (p: 0.233 and p: 0,203, respectively). Discussion: In our study, Apelin-12, IL-6, hs-CRP and RI levels were significantly higher in patients with CKD compared to the control group. In the diabetic subgroup, RI was significantly higher and Apelin-12 was significantly lower. Apelin-12 and RI values were found to be increased with increasing CKD stages which was statistically significantly. RI and Apelin-12 are thought to be used as indirect indicators of renal fibrosis. Although TGF-β1 and elasticity score were measured higher in the patient group, the lack of statistical significance is correlated with the limited number of patients included in the study. Significant results have been obtained that can contribute to the noninvasive methods used in early diagnosis and follow-up in CKD patients. We hope that our study will shed light on more broader and controlled study done in these issues. Keywords: chronic kidney disease, renal fibrosis, resistivity index, shear-wave elastography