The feasibility of one-stage flexible ureteroscopy lithotripsy in solitary kidney patients with 1–3 cm renal stones and risk factors of renal function changes

Figures & data

Table 1. Demographic, clinical, and stone-related data.

	Total	PS	NPS	p-Value
Number of patients, n	76	40	36
Age, years, mean ± SD	55.0 ± 12.3	55.0 ± 11.8	55.1 ± 13.0	0.947
Gender, n (%)
Male	43 (56.6)	23 (57.5)	20 (55.6)	0.864
Female	33 (43.4)	17 (42.5)	16 (44.4)
Weight, kg, mean ± SD	63.5 ± 11.6	63.7 ± 10.7	63.4 ± 12.7	0.907
Height, cm, mean ± SD	161.7 ± 8.8	160.7 ± 9.5	162.5 ± 8.0	0.449
BMI, kg/m^2, mean ± SD	24.3 ± 3.7	24.6 ± 3.5	23.9 ± 4.0	0.406
Etiology of solitary kidney, n (%)
Congenital renal agenesis	4 (5.3)	3 (7.5)	1 (2.8)	0.610
Contralateral nephrectomy	26 (34.2)	14 (35)	12 (33.4)
Contralateral nonfunctioning kidney	46 (60.5)	23 (57.5)	23 (63.8)
Preoperative comorbidities, n (%)
Cardiovascular disease	23 (30.3)	9 (22.5)	14 (38.9)	0.120
Diabetes mellitus	6 (7.9)	4 (10)	2 (5.6)	0.677
Preoperative urine culture results, n (%)
Positive	14 (18.4)	5 (12.5)	9 (250	0.160
Negative	62 (81.6)	35 (87.5)	27 (75)
Preoperative ASA Grade, n (%)
Grade 2	56 (73.7)	30 (75)	26 (72.2)	0.784
Grade 3	20 (26.3)	10 (25)	10 (27.8)
Greatest stone diameter, mm, mean ± SD	16.8 ± 4.7	17.7 ± 4.8	15.7 ± 4.4	0.070
Greatest stone diameter >20 mm, mean ± SD	24.0 ± 2.2	24.6 ± 1.9	23.1 ± 2.4	0.156
Greatest stone diameter <20 mm, mean ± SD	14.7 ± 2.8	15.4 ± 2.9	14.0 ± 2.6	0.490
Stone number, n, mean ± SD	1.6 ± 0.9	1.5 ± 0.8	1.7 ± 1.0	0.490
Single stone, n (%)	47 (61.8)	26 (65)	21 (58.3)	0.550
Multiple stones, n (%)	29 (38.2)	14 (35)	15 (41.7)
Greatest stone diameter, n (%)
More than or equal to 20 mm	17 (22.4)	10 (25)	7 (19.4)	0.562
Less than 20 mm	59 (77.6)	30 (75)	29 (80.6)
Stone side, n (%)
Left renal stones	36 (47.4)	19 (47.5)	17 (47.2)	0.981
Right renal stones	40 (52.6)	21 (52.5)	19 (52.8)
Stone location (main), n (%)
Renal pelvis	29 (38.1)	15 (37.5)	14 (38.9)	0.577
Upper calix	5 (6.6)	4 (10)	1 (2.8)
Middle calix	5 (6.6)	3 (7.5)	2 (5.5)
Lower calix	37 (48.7)	18 (45)	19 (52.8)

PS: prior stenting; NPS: not prior stenting; SD: standard deviation; BMI: body mass index; ASA Grade: Grading of patients for surgical procedures according to American Society of Anesthesiologists.

Table 2. Renal function changes and perioperative outcomes.

	Total (n = 76)	PS (n = 40)	NPS (n = 36)	p-Value
eGFR (adjusted for BSA) on, mL/min/1.73m^2, mean ± SD
Preoperatively	57.05 ± 19.37	57.34 ± 19.09	56.73 ± 19.94	0.891
Postoperative 1 month	57.52 ± 19.10	57.65 ± 20.27	57.38 ± 18.01	0.952
Postoperative 6 months	60.63 ± 20.54	60.45 ± 22.48	60.83 ± 18.46	0.937
Δ% eGFR at postoperative 6 months, n (%)
Improvement or stabilization	69 (90.9)	35 (87.5)	34 (94.4)	0.435
Deterioration	7 (9.2)	5 (12.5)	2 (5.6)
Surgical time, min, mean ± SD	49.9 ± 22.3	48.6 ± 22.6	51.4 ± 22.1	0.570
Postoperative hospital duration, days, mean ± SD	2.2 ± 1.6	2.3 ± 1.5	2.1 ± 1.6	0.186
Hemoglobin decline at postoperative 1 day, g/L, mean ± SD	5.8 ± 8.7	6.5 ± 9.5	4.9 ± 7.8	0.418
Success rate of UAS insertion, n (%)	74 (97.4)	40 (100)	34 (94.4)	0.221
Initial SFR at postoperative 1 month, n (%)	64 (84.2)	34 (85.0)	30 (83.3)	0.842
SFR after second procedures, n (%)	73 (96.1)	39 (97.5)	34 (94.4)	0.926
Postoperative main stone composition, n (%)
Calcium oxalate monohydrate calculi	24 (31.6)	14 (35)	10 (27.8)	0.673
Calcium oxalate and phosphate calculi	36 (47.4)	18 (45)	18 (50)
Uric acid calculi	6 (7.9)	2 (5)	4 (11.1)
Mixed calculi	10 (13.1)	6 (15)	4 (11.1)
Clavien–Dindo complications, n (%)
All	12/76 (15.8)	7/40 (17.5)	5/36 (13.9)	0.666
Grade I	5	3	2
Grade II	4	2	2
Grade III	3	2	1
Complications Classification
Transient postoperative pain or fevers requiring oral analgesics or antipyretics (Grade I)	5	3	2
SIRS/urinary sepsis requiring additional antibiotics (Grade II)	3	2	1
Fungal infection requiring antifungal drug (Grade II)	1	0	1
Ureteral steinstrasse requiring emergent URS (Grade III)	3	2	1

eGFR: estimated glomerular filtration rate; BSA: body surface area; IQR: interquartile range; Δ% eGFR: (the difference between timely level and baseline level)/baseline level × 100%; UAS: ureteral access sheath; SFR: stone free rate; SIRS: Systemic Inflammatory Response Syndrome; URS: ureteroscopy lithotripsy.

Figure 1. The changes in mean estimated glomerular filtration rate (eGFR) levels in the prior stenting group and non-stenting group. Both groups had an increase in mean eGFR levels compared with baseline levels.

Table 3. The odds ratios (ORs) with 95% confidence interval (CIs) of renal function deterioration using univariable logistic regression.

Variable	Univariable logistic regression
	Total (n = 76)	Deteriorated eGFR (n = 7)	Improved or stationary eGFR (n = 69)	OR (95% CI)	p-Value
Age, years, mean (SD)	55.0 (12.3)	52.9 (13.4)	55.3 (12.3)	0.984 (0.924–1.049)	0.622
Male, n (%)	43 (56.6)	4 (57.1)	39 (56.5)	1.026 (0.213–4.934)	0.975
BMI, kg/m^2, mean (SD)	24.3 (3.7)	25.3 (3.2)	24.2 (3.8)	1.083 (0.883–1.327)	0.445
ASA grade = 2, n (%)	56 (73.7)	6 (85.7)	50 (72.5)	2.280 (0.257–20.208)	0.459
Hypertension, n (%)	21 (27.6)	1 (14.3)	20 (29.0)	0.408 (0.046–3.612)	0.421
Diabetes mellitus, n (%)	6 (7.9)	0	6 (8.7)	0.000 (0.000)	0.999
Positive urine culture, n (%)	14 (18.4)	1 (14.3)	13 (18.8)	0.718 (0.079–6.488)	0.768
Contralateral nonfunctioning kidney, n (%)	46 (60.5)	5 (71.4)	41 (59.4)	1.094 (0.196–6.097)	0.919
Preoperative eGFR, mL/min/1.73m^2, mean (SD)	57.05 (19.37)	58.12 (20.41)	56.94 (19.41)	1.003 (0.963–1.045)	0.877
Greatest stone diameter, mm, mean (SD)	16.8 (4.7)	18.3 (5.8)	16.6 (4.6)	1.076 (0.919–1.260)	0.362
Patients with prior stenting, n (%)	40 (52.6)	5 (71.4)	35 (50.7)	2.429 (0.441–13.379)	0.308
Surgical time, min, mean (SD)	49.91 (22.27)	68.29 (10.98)	46.52 (20.00)	1.049 (1.009–1.090)	0.016

OR: odds ratios; CI: confidence interval; SD: standard deviation; BMI: body mass index; eGFR: estimated glomerular filtration rate (adjusted for body surface area); ASA Grade: Grading of patients for surgical procedures according to American Society of Anesthesiologists.

Table 4. Multivariable logistic regression model for renal function deterioration at postoperative 6 months.

	Multivariable logistic regression
Variable	OR (95% CI)	p-Value
Greatest stone diameter, mm	1.064 (0.878–1.289)	0.525
Prior stenting, n	4.214 (0.522–34.027)	0.179
Preoperative eGFR levels, mL/min/1.73m^2	1.004 (0.961–1.049)	0.842
Surgical time, min	1.061 (1.015–1.109)	0.009

OR: odds ratios; CI: confidence interval; eGFR: estimated glomerular filtration rate (adjusted for body surface area).

Data availability statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.