Pararenal Fat and Renal Dysfunction in Patients without Significant Cardiovascular Disease.

Introduction: Accumulation of fat tissue around the kidneys is considered to be a risk factor for chronic kidney disease (CKD). The objective of the study was to investigate the association of pararenal fat tissue (PRFT) and renal dysfunction in patients without clinically significant cardiovascular diseases (CVDs).

Methods: The study included 320 patients without CVDs (mean age 63.8 ± 13.9 years). All patients underwent anthropometric measurements, standard biochemical blood tests, including a lipid panel and uric acid concentration. Glomerular filtration rate (GFR) was calculated using the CKD-EPI formula. All patients underwent computed tomography of the abdomen with measurement of the PRFT thickness. The research results were processed using StatSoftStatistica 10.0 software.

Results: The average PRFT thickness was 1.45 cm [0.9; 2.0]. It was significantly higher in obese individuals when compared with patients with normal body weight (1.9 cm [1.3; 2.6] vs. 1.0 cm [0.6; 1.7]) and overweight people (1.9 cm [1.3; 2.6] vs. 1.1 cm [0.8; 1.6]) (p < 0.001). GFR was significantly higher in subjects with normal body weight when compared with obese patients (72 mL/min/1.73 m2 [59; 83] vs. 61 mL/min/1.73 m2 [51; 70]) and overweight patients (72 mL/min/1.73 m2 [59; 83] vs. 61 mL/min/1.73 m2 [54; 72]) (p < 0.001). PRFT thickness was significantly higher in patients with stage 3 CKD when compared with those with stage 1 CKD (2.2 cm [1.6; 3.3] vs. 0.9 cm [0.9; 1.0]) and with stage 2 CKD (2.2 cm [1.6; 3.3] vs. 1.3 cm [0.9; 1.8]) (p < 0.001). A significant correlation was found between PRFT thickness and body mass index (r = 0.49, p < 0.05), waist circumference (r = 0.55, p < 0.05), GFR (r = -0.47, p < 0.05), and uric acid level (r = 0.46, p < 0.05). Multiple linear regression analysis revealed a significant relationship between GFR and age (β ± SE -0.43 ± 0.15, p = 0.01), PRFT thickness (β ± SE -0.38 ± 0.14, p = 0.01) and with the level of low-density lipoprotein cholesterol (β ± SE -0.32 ± 0.12, p = 0.01). Logistic regression analysis showed that the risk of renal dysfunction development was associated with PRFT thickness (OR = 6.198; 95% CI: 1.958-19.617; p < 0.05). ROC analysis determined the threshold values of PRFT thickness (>1.68 cm, AUC = 0.875), above which the development of renal dysfunction can be predicted (sensitivity 63.2%, specificity 93.4%).

Conclusion: The results of our study indicate the relationship between PRFT and visceral obesity and renal dysfunction in patients without clinically significant CVDs.