(1) General information of the patients: See Table 1 for details.
Table 1
General information of the patients and univariate analysis ursults for SIRS after PCNL
Variable
|
SIRS(+)
|
SIRS(-)
|
total
|
P-value
|
Number of cases
|
106(30.11%)
|
246(69.89%)
|
352(100%)
|
|
Gender
|
|
|
|
|
male
|
60(56.60%)
|
150(61.00%)
|
210(59.7%)
|
0.443
|
female
|
46(43.40%)
|
96(39.00%)
|
142(40.3%)
|
|
Age
|
|
|
|
|
Male
|
53.53 ± 11.40
|
53.99 ± 9.37
|
55.20 ± 10.69
|
0.983
|
Female
|
54.63 ± 11.91
|
55.48 ± 10.10
|
54.4 ± 10.27
|
0.659
|
average
|
54.01 ± 11.58
|
54.57 ± 9.67
|
53.86 ± 9.97
|
0.661
|
Body Mass Index
|
24.95 ± 4.16
|
25.35 ± 4.98
|
25.22 ± 4.73
|
0.477
|
Urine culture
|
|
|
|
|
positive
|
1(0.90%)
|
8(3.25%)
|
9(2.6%)
|
0.373
|
negative
|
105(99.10%)
|
238(96.75%)
|
343(97.4%)
|
|
Rental stones
|
|
|
|
|
single
|
54(50.94%)
|
129(52.44%)
|
183(52.0%)
|
0.797
|
multiple
|
52(49.06%)
|
117(47.56%)
|
169(48.0%)
|
|
Hemoglobin
|
128.61 ± 20.34
|
19.40 ± 18.36
|
129.16 ± 18.97
|
0.722
|
Blood pressure
|
|
|
|
|
Systolic pressure
|
140.22 ± 19.41
|
140.45 ± 19.34
|
140.38 ± 19.36
|
0.155
|
Diastolic pressure
|
84.03 ± 10.00
|
83.26 ± 11.54
|
83.49 ± 11.08
|
0.552
|
Diabetes
|
|
|
|
|
Yes
|
11(10.38%)
|
48(1.68%)
|
59(16.8%)
|
0.035*
|
no
|
95(89.62)
|
198(98.32%)
|
293(83.2%)
|
|
Blood glucose
|
5.83 ± 1.62
|
5.85 ± 1.71
|
5.84 ± 1.68
|
0.927
|
Hydronephrosis
|
|
|
|
|
Yes
|
78(73.58%)
|
172(69.92%)
|
270(76.7%)
|
0.363
|
no
|
28(26.42%)
|
74(30.08%)
|
82(23.3%)
|
|
Renal failure
|
|
|
|
|
Yes
|
2(1.90%)
|
3(1.2%)
|
5(1.4%)
|
1.000
|
no
|
104(98.11%)
|
243(30.08%)
|
347(98.6%)
|
|
Fever before operation
|
|
|
|
Yes
|
9(8.49%)
|
15(6.10%)
|
24(6.8%)
|
0.002*
|
no
|
97(91.51%)
|
231(93.90%)
|
328(93.2%)
|
|
Operative time
|
61.87 ± 34.65
|
51.84 ± 24.78
|
54.86 ± 28.45
|
0.008*
|
Cast stone or staghorn stone
|
|
|
|
Yes
|
11(10.38%)
|
14(5.69%)
|
25(7.1%)
|
0.458
|
no
|
95(89.62%)
|
232(94.31%)
|
327(92.9%)
|
|
History of stone surgery
|
|
|
|
Yes
|
45(42.45%)
|
115(46.75%)
|
160(45.5%)
|
༜0.001**
|
no
|
61(57.55%)
|
131(53.25%)
|
192(54.5%)
|
|
Stone clearance rate
|
|
|
|
Stone removal
|
105(99.06%)
|
241(97.97%)
|
346(98.30%)
|
0.783
|
residual stone
|
1(0.94%)
|
5(2.03%)
|
6(1.70%)
|
|
hospital stays
|
14(13,18)
|
14(12,16)
|
|
|
Guy’s degree
|
|
|
|
|
1
|
4(3.77%)
|
6(2.44%)
|
10(2.84%)
|
0.019*
|
2
|
74(69.81%)
|
206(83.74%)
|
280(79.55%)
|
|
3
|
17(16.04%)
|
20(8.13%)
|
37(10.51%)
|
|
4
|
11(10.38%)
|
14(5.69%)
|
25(7.10%)
|
|
A total of 352 patients who underwent PCNL for renal stones were included in the present study. Among them, 210 were males (59.7%), and 142 were females (40.3%). The average age was 53.86±9.97 years, the average body mass index was 25.22±4.73, and the average operative time was 54.86±28.45. Nine patients (2.6%) were positive for preoperative urine culture, 169 patients (48%) had multiple renal stones, 25 patients (7.1%) had cast stones or staghorn stones, and 59 patients (16.8%) had concurrent diabetes. The average preoperative blood glucose level was 5.84±1.68 mml/L. There were 270 cases (76.7%) with concurrent hydronephrosis, 5 cases (1.4%) with concurrent renal insufficiency, 24 cases (6.8%) with preoperative fever, 160 cases (45.5%) with a preoperative history, 106 cases (30.1%) with SIRS, and no patients with sepsis. There was no difference between the SIRS and non-SIRS groups in terms of age, gender, or BMI.
(2) Results of univariate analysis for SIRS after percutaneous nephrolithotomy: It was found in the univariate analysis that the differences in operative time, preoperative fever, diabetes and previous stone operative history were statistically significant, with p<0.05, as shown in Table 2.
Table 2
Multivariate logistic regression analysis results for SIRS after PCNL
Variable
|
OR
|
95% confidence interval
|
P-value
|
Diabetes
|
2.038
|
1.006~4.130
|
0.048
|
Operative time
|
1.012
|
1.004~1.020
|
0.004
|
(3) Results of multivariate logistic regression analysis for SIRS after PCNL: Variables with p<0.2 in the univariate analysis, including gender, systolic pressure, diabetes, fever before operation, operative time, and history of stone surgery, were selected for logistic regression. It was found in the multivariate analysis that diabetes and operative time were risk factors, as shown in Table 2; as a result, the predictive regression model P=1/[1+e-(-2.097+0.712 diabetes + 0.012 operative time)] was established. For example, nondiabetic patients, 60 minutes of operation, p=0.21; nondiabetic patients, 120 minutes of operation, p=0.34; diabetic patients, 60 minutes of operation, p=0.35; and diabetic patients, 120 minutes of operation, p=0.51. The risk probability can be obtained according to the risk factors, so medical staff can perform targeted observation for SIRS in postoperative patients.
(4) A nomogram was established incorporating two predictive factors (diabetes and operative time) (Fig 1). Operative time made the largest contribution to SIRS risk, After the sum of the points is located on the total points axis, the sum represents the probability of SIRS when survival is visualized by drawing a line straight down to the SIRS axis. For example, PCNL lasted for sixty minutes (28 points) in diabetic (28 points) patients. The point total was 56 This predictive value could be used to make decisions for clinical treatment and patient counseling.
The C-index for the predictive model was 0.608 [95% confidence interval (CI): 0.504-0.748], which showed discrimination ability. The ROC curve is presented in Fig 2. The H-L chi-square statistic was 12.834, which indicated good statistical performance upon internal validation between the nomogram prediction and the actual observation for the probability of SIRS (P=0.196). The calibration plot is shown in Fig 3.
The red solid line is a smoothed curve that represents an estimate of the relation between the predicted and observed probability of SIRS. Ideally, this line fits the black solid line that represents perfect calibration.