Establish and validate a nomogram to predict the risk of pyonephrosis based on the difference in average CT attenuation values between renal pelvis urine and bladder urine
10.3760/cma.j.cn112330-20241007-00437
- VernacularTitle:基于肾盂尿和膀胱尿平均CT值的差值预测肾积脓风险列线图的建立和验证
- Author:
Shuchao YE
1
;
Dongming LU
;
Shangfan LIAO
;
Quan WEI
;
Yangfan LIANG
;
Shengtai LI
;
Yongyang WU
Author Information
1. 福建医科大学附属三明第一医院泌尿外科，三明 365000
- Publication Type:Journal Article
- Keywords:
Pyonephrosis;
Hydronephrosis;
CT attenuation value;
Nomogram;
Model statistical
- From:
Chinese Journal of Urology
2025;46(2):97-103
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To explore the predictive value of the difference in average CT attenuation values between renal pelvis urine and bladder urine on the risk of pyonephrosis, and to establish a nomogram model in combination with other parameters and to verify its predictive ability.Methods:The clinical data of patients with obstructive hydronephrosis who came to our hospital for emergency percutaneous nephrostomy (PCN) between January 2020 and December 2022 were retrospectively analyzed. There were 16 men and 33 women, with the age of (57.59, 14.67) years. Body mass index was (23.34, 3.11) kg/m 2. Urine nitrite was positive in 14 cases. Urine culture was positive in 21 cases. In the routine blood test, the median white blood cell count was 10.96 (7.21, 15.15) ×10 9/L, haemoglobin (115.08, 22.71) g/L and platelets (263.00, 97.20)×10 9/L. The difference in average CT attenuation values between renal pelvis urine and bladder urine (mean CT value of pyelonephritis-mean CT value of cysturia) was -2.19 (-7.04, 4.05) HU. Patients were divided into pyonephrosis group and hydronephrosis group according to whether the drainage fluid after PCN was pus. Single-factor and multi-factor logistic regression models were used to analyze the independent predictors of pyonephrosis and to construct nomograms. The discrimination of the model was assessed by the area under the curve (AUC) of the receiver operating characteristics (ROC), the accuracy by the calibration curve and the clinical efficacy by the decision curve analysis (DCA). Results:There were 49 cases in this study, 31 cases in the hydronephrosis group and 18 cases in the pyonephrosis group. The average CT attenuation values of renal pelvis urine were 3.35(0.56, 8.96) HU and 7.78 (3.75, 18.38) HU, respectively, and the difference between the two groups was statistically significant ( P=0.023). The average CT attenuation values of bladder urine were (7.81±6.15)HU and (7.22±7.50)HU, respectively, and there was no significant difference between the two groups ( P=0.780). The difference in average CT attenuation values between renal pelvis urine and bladder urine were -3.98(-7.54, 0.60)HU and 2.13 (-5.15, 9.36)HU, respectively, and the difference between the two groups was not statistically significant ( P=0.059); the white blood cells were 9.82(7.04, 12.46) ×10 9/L and 13.99(9.75, 18.44) ×10 9/L, respectively, and the difference between the two groups was statistically significant ( P=0.048). Platelet counts were (248.06±87.87)×10 9/L and (288.72±109.29)×10 9/L, respectively, and there was no statistical difference between the two groups ( P=0.189). The proportion of urine protein positive was higher in the pyonephrosis group (17 vs. 20, P=0.048). Between the two groups, sex, age, body mass index, clinical symptoms (with or without low back pain), surgical history of upper urinary tract stones, underlying diseases (including hypertension, diabetes, coronary heart disease, etc.), location of hydronephrosis (left, right, and both sides), reasons of obstruction [upper urinary tract stones, other factors (such as tumor, ureteral stricture, etc.)], haemoglobin, were not statistical different. There were no significant difference in blood glucose, blood potassium, blood sodium, urine leukocytes, urine erythrocytes, urine nitrite and urine culture ( P>0.05). Multivariate logistic regression analysis showed that the difference in average CT attenuation values between renal pelvis urine and bladder urine ( OR=1.196, 95% CI 1.055-1.437, P=0.018), white blood cells ( OR=1.252, 95% CI 1.036-1.615, P=0.038), and platelets ( OR=1.014, 95% CI 1.003-1.030, P=0.025) were independent predictors of pyonephrosis. According to the above indicators, the nomogram model was established and the AUC value of the model was 0.767 (95% CI 0.616-0.918), the sensitivity was 0.611 and the specificity was 0.935. The calibration curve showed that there is a good fit between the observed value and the predicted value. The DCA analysis showed that the nomogram model has a net gain in a wide threshold range, demonstrating its predictive accuracy and clinical practicality in predicting the risk of pyonephrosis. When the cut-off value of the difference between the average CT values of pyelonephritis and cystourethrosis was 6.54 HU, the AUC value of the independent prediction of pyonephrosis was 0.690(95% CI 0.564-0.816), the sensitivity was 0.444 and the specificity was 0.935. Conclusions:The difference in average CT attenuation values between renal pelvis urine and bladder urine is an independent risk factor for predicting pyonephrosis, and the nomogram constructed by combining it with white blood cells and platelets has a good predictive effect for predicting the risk of pyonephrosis. If the difference in average CT attenuation values between renal pelvis urine and bladder urine is greater than 6.54HU, it should be alert to the occurrence of pyonephrosis.
