Risks and Benefits of Postoperative Double-J Stent Placement After Ureteroscopy: Results from the Clinical Research Office of Endourological Society Ureteroscopy Global Study

Abstract

Purpose:

Double-J stent placement after stone removal by ureteroscopy (URS) is common and recommended in many cases but debatable in others. In this study, the risks and benefits of postoperative Double-J stent placement in URS stone treatment procedures undertaken in current clinical practice are examined.

Materials and Methods:

The Clinical Research Office of Endourological Society (CROES) URS is a prospective, observational, international multicenter study, in which patients are candidates for URS as primary treatment or after failure of prior treatment for ureteral and renal stones. Baseline, intraoperative, and postoperative data were collected. Predictors and outcomes of postoperative stent placement were analyzed by inverse probability-weighted regression adjustment of the relationship between a Double-J stent placement and outcomes (complications, readmission [including retreatment], and length of hospital stay).

Results:

Significant predictors of postoperative Double-J stent placement in URS treatment of ureteral stones were intraoperative complications, impacted stones, operation time, stone burden, age, presence of a solitary kidney, and stone-free rate. In renal stone treatment, the predictors identified included operation time, age, preoperative stent placement, anticoagulant use, presence of a solitary kidney, and intraoperative complications. In both ureteral and renal stone treatment groups, postoperative placement of a Double-J stent resulted in significantly fewer postoperative complications (p < 0.001) compared with patients who did not receive a stent.

Conclusions:

Patient- and procedure-related variables were identified, which may enable an individualized approach to postoperative stenting, resulting in improved clinical outcomes in urologic stone treatment by URS.

Introduction

While the majority of urinary stones passes spontaneously,¹ there are others that merit intervention. Current European Association of Urology (EAU) guidelines on urolithiasis provide recommendations to guide decisions for observation with regular follow-up or active treatment and procedure selection, based on stone composition, location, number and size, as well as patient factors.² Indications for the removal of ureteral and kidney stones include persistent pain or obstruction, renal insufficiency, stone growth, stones in high-risk patients for stone formation, stone recurrence, symptomatic stones causing infection, pain or hematuria, large stones (>15 mm) and the preferences, comorbidities, and social situation of the patient.²

Over the past 20 years, ureteroscopy (URS) has evolved into a first-line option for the management of urinary stones.³ Technological advances have produced small-caliber scopes, with better deflection mechanisms and durability. Consequently, a significant increase in the use of URS mirrored by a decrease in other low- or minimally invasive options for urinary stone management is shown.^4

–7 Confirming the clinical effectiveness of URS, the EAU guidelines specify that this technique can be performed to remove ureteral stones in all patients without any definite contraindications other than those with general problems, such as unsuitability for general anesthesia or untreated urinary tract infections.²

Placement of a Double-J stent after URS is intended to prevent obstruction, renal colic, and deterioration of renal function, and it has been recommended, including by the EAU guidelines, that stents are placed in patients who are at increased risk of complications.^2,8 The use of a postoperative stent after an uncomplicated procedure, however, is not considered to be necessary and remains a matter of debate.^2,9

The aim of the Clinical Research Office of Endourological Society (CROES) URS Global Study was to review current practice and to define the risks and benefits of postoperative Double-J stent placement in both complicated and uncomplicated URS procedures.

Patients and Methods

Patients

The CROES URS Global Study was a prospective, observational, international multicenter study that included 11,885 patients who were treated with URS at 114 Urology Departments with URS expertise across 32 countries.¹⁰ In brief, each participating center included all consecutive patients who were treated during a 1-year period beginning with the first patient treated between January 2010 and October 2012. Treatment with semirigid or flexible URS was conducted according to local availability and protocols.

Data collection

For every patient, baseline characteristics, - and postoperative information, and 3-month follow-up information were collected, as described in more detail elsewhere.¹⁰ Baseline characteristics recorded included age, gender, American Society of Anesthesiologists (ASA) score, body mass index (BMI), and medical history regarding congenital abnormalities, solitary kidney, previous stone treatment, and anticoagulant use. Stone dimensions were measured and used to calculate stone burden as the sum of all stone sizes: length (mm) × width (mm) × 0.25 × 3.14159. Intraoperative characteristics collected were duration of procedure, intraoperative complications, and stone-free status. Postoperative outcome data collected were long hospital stay (defined as longer than 1 day), readmission (any possible procedure-related hospital visit, including retreatment), and postoperative complications according to the Clavien–Dindo grading system.¹¹

Statistical analyses

Descriptive data are presented as mean (standard deviation) for normally distributed continuous variables and as median (interquartile range) for skewed continuous variables. Dichotomous, categorical, and ordinal variables are presented as number (%). Data are shown separately for URS treatment of ureteral and kidney stones because these procedures have shown to be treated differently.

To predict postoperative stent placement, the following preoperative and intraoperative characteristics were evaluated: ASA score, age, gender, BMI, stone burden, previous stone treatment, preoperative stent placement, ureteroscope size, impacted stones, operation time, and intraoperative complications.

Because of the probable imbalanced nature (i.e., according to the guidelines, patients at risk are treated with a postoperative stent) of baseline characteristics between the groups with and without stent placement, inverse probability-weighted regression adjustment (IPWRA) was used.^12,13 An average treatment effect is calculated based on these weighted probabilities, representing the effect of treatment over nontreatment weighted for differences at baseline between the treatment and nontreatment groups. The multivariate prediction model described above was used as the treatment model. Postoperative complications, readmission (including retreatment), and length of hospital stay are used as outcome measures. The final outcome models are corrected for the treatment model of postoperative stent placement. All statistical analyses were performed using STATA version 13, StataCorp LP, College Station, TX (www.stata.com).

Results

Only patients treated solely for either ureteral or renal stones, with known information on postoperative stent use (n = 10,437), were included in the current analysis. Of these patients, a Double-J stent was placed postoperatively in 5458 (63.2%) ureteral URS procedures and in 1436 (79.5%) renal URS procedures (Table 1). Postoperative Double-J stent use varied between countries from 29% to 96% (Fig. 1).

FIG. 1.

Postoperative Double-J stent use in different countries participating in the CROES URS Global Study. Only countries recruiting more than 50 patients are shown. CROES = Clinical Research Office of the Endourological Society; URS = ureteroscopy.

Table 1.

Patient and Operative Characteristics of Ureteroscopy Procedures for Ureteral and Renal Stones With and Without Postoperative Double-J Stent Placement

	Ureteral stones		Renal stones
	With stent (N = 5458)	Without stent (N = 3172)	With stent (N = 1436)	Without stent (N = 371)
Patient and preoperative characteristics
ASA score
I	2964 (57.4)	1866 (62.4)	502 (38.2)	122 (37.8)
II	1762 (34.1)	941 (31.5)	591 (44.9)	155 (50.0)
III	424 (8.2)	169 (5.7)	211 (16.0)	43 (13.3)
IV	17 (0.3)	14 (0.5)	12 (0.9)	3 (0.9)
N	5167	2990	1316	323
Age (years), mean (SD)	49 (15.6)	46 (16.3)	51 (14.7)	48 (16.7)
N	4978	2416	1288	311
Gender
Male	3567 (65.4)	2152 (67.9)	832 (57.9)	241 (65.0)
Female	1887 (34.6)	1016 (32.1)	604 (42.1)	130 (35.0)
BMI (kg/m²), mean (SD)	26.6 (4.6)	26.4 (4.8)	27.8 (7.1)	27.1 (5.8)
N	4851	2358	1281	310
Renal congenital abnormality	120 (2.2)	47 (1.5)	96 (6.7)	26 (7.0)
Solitary kidney	135 (2.5)	84 (2.7)	41 (2.9)	16 (4.3)
Anticoagulant use	286 (5.3)	117 (3.7)	118 (8.4)	40 (11.2)
Stone location
Proximal	1764 (32.3)	599 (18.9)	—	—
Mid	1294 (23.7)	507 (16.0)	—	—
Distal	2199 (40.3)	1982 (62.5)	—	—
Multiple	201 (3.7)	84 (2.6)	—	—
Upper pole	—	—	112 (7.8)	41 (11.0)
Interpolar	—	—	104 (7.2)	47 (12.7)
Lower pole	—	—	475 (33.1)	129 (34.8)
Renal pelvis	—	—	379 (26.4)	64 (17.3)
Multiple	—	—	366 (25.5)	90 (24.3)
Stone burden (mm²), median (IQR)	56 (28–88)	50 (27–79)	79 (28–192)	55 (13–143)
Previous calculus treatment
SWL	855 (15.8)	571 (18.2)	360 (25.4)	116 (31.9)
Nephrostomy	210 (3.9)	109 (3.5)	44 (3.1)	20 (5.5)
PCNL	157 (2.9)	109 (3.5)	188 (13.2)	48 (13.1)
Pyelolithotomy	65 (1.2)	32 (1.0)	26 (1.8)	7 (1.9)
UPJ pyeloplasty	6 (0.1)	5 (0.2)	16 (1.1)	3 (0.8)
URS	498 (9.2)	394 (12.5)	325 (22.9)	121 (32.7)
Preoperative Double-J stent	644 (11.8)	436 (13.8)	478 (33.3)	160 (43.1)
Intraoperative characteristics
Operation time (minutes), median (IQR)	35 (25–58)	35 (20–60)	61 (45–95)	50 (32–75)
Intraoperative complications	85 (1.6)	16 (0.5)	12 (0.8)	16 (4.3)
Stone-free status
Treated area	4840 (89.3)	2992 (93.4)	1031 (73.5)	278 (76.6)
N	4840	2922	1403	363
Postoperative characteristics
Readmission	471 (9.1)	122 (4.1)	173 (13.2)	36 (10.2)
Ureter obstruction	14 (12.0)	24 (5.1)	5 (13.9)	6 (3.5)
Ureteral stricture	2 (1.7)	25 (5.3)	—	2 (1.2)
Ureteral stent discomfort	12 (9.9)	63 (13.4)	—	10 (5.8)
Flank pain	17 (14.1)	53 (11.3)	5 (13.9)	28 (16.2)
Bleeding	4 (3.3)	11 (2.3)	1 (2.8)	7 (4.1)
Sepsis	7 (5.8)	22 (4.7)	2 (5.6)	12 (6.9)
Other	24 (66.7)	123 (71.1)	13 (54.2)	75 (72.1)
Long hospital stay	1896 (34.8)	1086 (34.5)	473 (33.1)	135 (36.5)
Retreatment	654 (12.0)	160 (5.1)	199 (13.9)	24 (6.5)
Postoperative complications	77 (1.4)	42 (1.3)	59 (4.1)	38 (10.2)
Bleeding	22 (17.2)	9 (16.1)	10 (12.1)	3 (7.5)
Fever	40 (31.3)	16 (28.6)	13 (15.7)	9 (22.5)
UTI	30 (23.4)	14 (25.0)	23 (27.7)	7 (17.5)
Lung embolism	1 (0.8)	—	1 (1.2)	—
CVA	1 (0.8)	—	—	—
Sepsis	10 (7.8)	4 (7.1)	11 (13.3)	3 (7.5)
Acute abdomen	1 (0.8)	1 (1.8)	1 (1.2)	1 (2.5)
AMI	1 (0.8)	—	—	—
Pain	10 (7.8)	7 (12.5)	7 (8.4)	12 (30.0)
Urinary retention	2 (1.6)	—	5 (6.0)	—
Stent	4 (3.1)	2 (3.6)	3 (3.6)	2 (5.0)
Allergy	3 (2.3)	—	1 (1.2)	2 (5.0)
Death	—	—	1 (1.2)	—
Other	3 (2.3)	1 (1.8)	7 (8.4)	1 (2.5)
Access sheath use	122 (3.9)	497 (9.1)	218 (58.8)	928 (64.6)

Data are n (%) of patients for whom data were available. Percentages exclude missing values from denominators.

ASA = American Society of Anesthesiologists; BMI = body mass index; SWL = extracorporeal shockwave lithotripsy; IQR = interquartile range; PCNL = percutaneous nephrolithotomy; SD = standard deviation; UPJ = ureteropelvic junction; URS = ureteroscopy.

Multivariate regression analysis identified intraoperative complications, impacted stones, operation time, stone burden, age, presence of a solitary kidney, and stone-free rate as predictors of postoperative stent placement (Table 2). Corresponding analysis of renal stone treatment identified operation time, age, preoperative stent placement, anticoagulant use, presence of a solitary kidney, and intraoperative complications as significant predictors of postoperative Double-J stent placement in these URS procedures (Table 2). For both ureteral and renal stones, gender was not found to be a confounder or effect modifier. Both prediction models were used in the second-stage IPWRA analyses to examine clinical outcomes after a postoperative placement of a Double-J stent.

Table 2.

Significant Predictors Identified by Multivariate Best Prediction Modeling for Postoperative Double-J Stent Placement During Ureteral and Renal Stone Treatment

Predictor	Odds
Ureteral stones
Intraoperative complications	2.28
Impacted stones	1.58
Operation time (log)	1.26
Stone burden (log)	1.08
Age	1.01
Solitary kidney^a	0.62
SFR	0.44
Renal stones
Operation time (log)	1.75
Age	1.02
Preoperative stent placement	0.77
Anticoagulant use	0.51
Solitary kidney	0.49
Intraoperative complications	0.16

Most patients with a solitary kidney had a stent inserted preoperatively.

SFR = stone-free rate.

Figure 2 shows the probability of postoperative Double-J stent placement, as presented in Table 2, against the patients whom actually have received a postoperative Double-J stent for ureteral and renal procedures. This figure shows how much the models, that is, the likelihood of receiving a stent in theory, fit with real life data.

FIG. 2.

The probability of postoperative Double-J stent placement compared with stent placement recorded in (A) ureteral stone URS treatment and (B) renal stone URS treatment.

The effect of postoperative stent placement on clinical outcomes of ureteral and renal URS procedures is shown in Table 3. In ureteral procedures, postoperative stent placement significantly decreased the probability of a long hospital stay and of postoperative complications but increased hospital readmissions. In renal procedures, postoperative complications were also significantly reduced by postoperative Double-J stent placement, but there was no significant effect on the length of hospital stay or readmission rate.

Table 3.

Average Treatment Effects of Post-Operative Double-J Stent Placement on Outcomes of Ureteroscopy Treatment of Ureteral and Renal Stones Predicted by Inverse Probability-Weighted Regression Adjustment Models

Treatment outcome	ATE (%) ^a	p
Ureteral stones
Long hospital stay	−19.6	<0.001
Readmission	27.7	0.005
Complications	−40.1	0.005
Renal stones
Long hospital stay	−2.6	0.781
Readmission	12.2	0.449
Complications	−69.3	<0.001

The ATE% is the percentage change in probability of an outcome that can be attributed to postoperative Double-J stent placement relative to no stent placement.

ATE = average treatment effect.

Discussion

Ureteral stent placement after URS is advocated by a “no pain, no gain” approach to prevent obstruction, ureteral stricture, colic, and renal failure due to ureteral edema or the passage of stone fragments and clots. In contrast, the associated increases in operation time, morbidity, and costs can be avoided by not placing a stent.^14
–16 Despite the current EAU guidelines on the use of a postoperative Double-J stent,² ultimately, the question of stent placement is left to the discretion of the treating physician. Deciding which procedures are “uncomplicated” is clearly key to this decision, and for this reason, selective individualized postoperative Double-J stenting based on risk stratification has been proposed.^9,17

In the CROES URS Global Study cohort, a postoperative Double-J stent was inserted in ∼60% of patients treated for ureteral stones. For renal stone URS treatment, the frequency of postoperative stenting was higher with ∼80% of patients. Thus, we can conclude that in current practice postoperative stent placement is more common after renal stone than after ureteral stone treatment.

The presence of a solitary kidney and being stone free predict postoperative stent placement in ureteral stone procedures, which is consistent with treatment guidelines.² The presence of impacted stones, older age, longer operating times, high stone burden, or intraoperative complications are all characteristics that prevent or decrease risk of postoperative complications. Thus, postoperative stent placement as recommended for higher risk cases or where there is doubt is suggested.²

In the treatment of renal stones, postoperative stent placement was more likely in patients with prolonged operation time and older age, both factors that might contribute to complicated procedures. Patients with a solitary kidney or anticoagulant use and procedures with preoperative Double-J stent placement or resulting in intraoperative complications were less likely to have a postoperative Double-J stent placement. For solitary kidney cases, as noted above, and patients presented for other reasons, the stent may remain in place, obviating the need for postoperative stent placement. It is perhaps surprising that intraoperative complications and anticoagulant use predicted that postoperative Double-J stent use was less likely. This could be due to the fact that, for complicated renal stone procedures, the treating physician chooses not to place a stent postoperatively and to monitor patients more closely in hospital. Length of hospital stay did not differ between stented and nonstented patient treated for renal stones.

Current results show that in both ureteral and renal stone treatment groups, postoperative placement of a Double-J stent resulted in fewer postoperative complications compared with patients who did not receive a stent. This finding contrasts with the established view that postoperative stents increase complications, lower urinary tract symptoms, and pain.^16,18 In the ureteral stone treatment group, significant differences in long hospital stays (decreased) and readmissions (increased) were found for patients stented postoperatively. With renal stone treatment, there appeared to be similar trends that, in the smaller treatment group, were not significant.

The multivariate models used to predict postoperative stent placement are best fit within the selected study population, which we believe is representative of URS procedures currently practiced around the world. In addition, the variables used in these models are based on sound biological or clinical considerations. Although current results suggest that gender was no confounder or effect modifier, differences found in other studies concerning postoperative infection¹⁹ suggest that separate analyses for males and females might be justified.

We acknowledge that this analysis does not capture all information relevant to postoperative stent placement. The overlap of probability versus reality of stent placement implies that there is scope for improvement in prediction of stent placement decision-making in the operating room. Despite these limitations, we believe that this study provides a basis for an individualized postoperative stenting strategy capable of refining the dichotomous classification of procedures as being complicated or not and supporting individualized treatment decisions.

Conclusions

Postoperative Double-J stent placement in URS treatment of ureteral and renal stones can be predicted by several patient- and procedure-related variables and is associated with improvement of some clinical outcomes, such as fewer postoperative complications, compared with not stenting postoperatively. These findings support the development of an individualized postoperative stenting strategy.

Footnotes

Acknowledgments

The CROES URS Global Study was supported by an unrestricted educational grant from Boston Scientific, who had no involvement in the design, collection, analysis, interpretation, or reporting of the data. Dr. Nienke Wijnstok provided statistical support for the analyses reported.

Author Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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