Outcomes of Retrograde Intrarenal Surgery Compared with Percutaneous Nephrolithotomy in Elderly Patients with Moderate-Size Kidney Stones: A Matched-Pair Analysis

Abstract

Purpose:

The aim of our study was to evaluate the outcomes of retrograde intrarenal surgery (RIRS) in elderly patients with stones of moderate size.

Patients and Methods:

Between September 2008 and June 2011, a total of 28 patients over 65 years of age with single renal stones that measured 1.5 to 3 cm were treated with RIRS. The outcomes of these patients were compared with those of the patients who underwent percutaneous nephrolithotomy (PCNL) using matched-pair analysis (1:1 scenario). The matching parameters were the size and location of the stone as well as age, sex, body mass index, degree of hydronephrosis, presence of previous shockwave lithotripsy, and open surgery. SPSS version 16 was used for statistical analysis.

Results:

Stone-free rates after a single procedure were achieved in 82.1% of patients for the RIRS and 92.8% of patients for the PCNL group. The second flexible ureterorenoscopy procedure was performed for five patients in the RIRS group. Finally, stone-free rates during the third month of the follow-up period were 92.8% in the RIRS group and 96.4% in the PCNL group. The mean operative time per patient was 64.5±20.9 minutes in the RIRS group after a total of 33 procedures, while it was 40.7±10.7 minutes in the PCNL groups (P<0.0001). The overall complication rates for the RIRS and PCNL groups were 7.1% and 10.7%, respectively. Blood transfusions were needed in two patients in the PCNL group. Hospitalization time was significantly shorter in the RIRS group (26.5±10.6 h per patient vs 60.0±28.8 h; P<0.0001). In both groups, stones were most frequently composed of calcium oxalate (68.4% in the RIRS group and 77.7% in the PCNL group).

Conclusion:

RIRS has a low complication rate and represents a safe and effective treatment alternative in selected geriatric patients with kidney stones of moderate size.

Introduction

I n American and European urology guidelines, shockwave lithotripsy (SWL) and percutaneous nephrolithotomy (PCNL) have been recommended as first-line treatment alternatives for renal stones of <2 and >2 cm in diameter, respectively.^1,2 Although higher stone-free rates were achieved with PCNL (depending on the stone size), severe complications, such as bleeding necessitating blood transfusions, visceral organ injuries, and hydrothorax, were observed.^3,4 Especially for geriatric patients whose cardiopulmonary and renal functions are decreased, certain complications of PCNL might become even more important; these patients would not tolerate invasive surgical interventions. Retrograde intrarenal surgery (RIRS), however, can minimize the above mentioned complications related to PCNL. In addition, in line with advancements in flexible ureterorenoscopy, stone-free rates comparable with those obtained by PCNL can be achieved.

The goal of our study was to evaluate the outcomes of RIRS in elderly patients with stones of moderate size. A secondary goal was to compare RIRS results with those of an age-matched cohort treated with PCNL.

Patients and Methods

Between September 2008 and June 2011, 28 patients more than 65 years of age with a single renal stone measuring 1.5 to 3 cm in diameter were treated with RIRS. Intravenous urography (IVU) and/or CT were performed in all patients. Patients' demographic parameters, including age, sex, body mass index (BMI), history of ipsilateral kidney surgery as well as the size, number, and location of the stones were recorded. Preoperative laboratory tests included serum creatinine and hemoglobin measurements, platelet counts, coagulation screening tests, and urine cultures. All patients had sterile urine culture before surgery. Preoperatively, all patients signed informed consent forms. Stone size was assessed as the surface area, which was calculated according to European Association of Urology guidelines.²

Within the same period, 79 geriatric (>65 years of age) patients with similar-sized stones underwent PCNL. From this cohort, we selected 28 patients to serve as the control group in this study. The 28 patients were retrospectively matched at a 1:1 ratio to index RIRS-PCNL cases with respect to the size, number and location of the stones, as well as age, sex, BMI, history of previous ipsilateral open surgery, and SWL. The baseline demographics and clinical data are given in Table 1 for each group.

Table 1.

Matched Pair Analysis of Preoperative Factors for Retrograde Intrarenal Surgery and Percutaneous Nephrolithotomy

Matched parameters	RIRS group	PCNL group	P value
Mean age (y) (mean±SD)	68.9±4.1	68.8±3.7 (65–78)	0.90
Mean BMI (kg/m²) (mean±SD)	28.5±4.2 (21.5–35.2)	27.4±5.7 (21.0–46.9)	0.38

	n (%)	n (%)
Sex			0.42
Male	13 (46.4)	16 (57.1)
Female	15 (53.6)	12 (42.9)
Stone localization			0.88
Upper calices	4 (14.3)	3 (10.7)
Middle calices	2 (7.1)	2 (7.1)
Lower calices	19 (67.9)	18 (64.3)
Pelvic	3 (10.7)	5 (17.9)
Previous open surgery			1.00
(+)	4 (14.3)	3 (10.7)
(−)	24 (85.7)	25 (89.3)
History of SWL			0.78
(+)	9 (32.1)	11 (39.3)
(−)	19 (71.4)	17 (60.7)

RIRS=retrograde intrarenal surgery; PCNL=percutaneous nephrolithotomy; SD=standard deviation; BMI=body mass index; SWL=shockwave lithotripsy.

PCNL technique

Briefly, access was performed under C-arm flouroscopy using an 18-gauge needle with the patient in the prone position as previously described in detail.⁵ The tract was dilated with a high-pressure balloon dilator (NephroMax™ Microvasive, Boston Scientific Corporation, Natick, MA). Fragmentation of the stone burden was accomplished using a pneumatic (Vibrolith,^® Elmed, Ankara, Turkey) or ultrasonic lithotripter (Swiss Lithoclast,^® EMS Electro Medical System, Nyon, Switzerland). A 14F nephrostomy tube was placed inside the renal pelvis or the involved calix on termination of the intervention in the majority of cases. The operative time was calculated from the puncture for an access tract to the final placement of a nephrostomy tube.

RIRS technique

A standardized RIRS procedure was performed in all cases as described elsewhere.⁶ In the RIRS procedure, all the stages of the procedure was performed with the patient in the lithotomy position on an endourologica table and under C-arm fluoroscopy control. In the beginning of the procedure, we performed rigid ureteroscopy both to visualize inside the ureter (for any unexpected pathology) and to facilitate placing the ureteral access sheath. The presence of a narrowing part of the ureter, in any location from ureteral orifice to proximal ureter, that would not allow us to advance the ureteral access sheath was the indication for performing balloon dilation. A ureteral access sheath was placed in 25 of 28 cases. In the remaining ones, a ureteral access sheath was not placed because of a narrow ureter part.

A 7.5F fiberoptic (Storz FLEX-X², Tuttlingen, Germany) or 8.7F digital flexible ureteroscope (DUR-D Gyrus ACMI, Southborough, MA) and a 200- or 273-μm laser fiber were used during the intervention. We used a holmium laser machine set at 1.0 to 1.5 J and 8 to 10 Hz. At the end of laser lithotripsy, stone fragments <2 mm were left for spontaneous passage, and basket stone retrieval was performed for fragments >2 mm. A systematic inspection of the collecting system was performed at the end of the procedure to confirm the achievement of adequate fragmentation and stone clearance. A 4.8F Double-J stent was routinely placed for each patient and then removed 3 weeks after the procedure. The operative time was defined as the time that passed from insertion of a cystoscope to the completion of stent placement.

Initial postoperative stone-free rates were determined at the time of hospital discharge with radiography of the kidneys, ureters, and bladder (KUB). Postoperatively, stone-free rates were mostly determined in an outpatient clinic setting at 3-month intervals with low-dose spiral CT. Stone-free status, however, was evaluated with IVU in two patients in the RIRS group and three patients in the PCNL group. The procedure was considered successful if the patient was stone free.

Statistical analysis

Data were analyzed with software SPSS 16.0 for Windows (SPSS, Chicago, IL). Normality test (Kolmogorov-Smirnov test, P>0.05) was performed to evaluate distributions of numeric variables. If the distribution of numeric variables were normal, statistical analysis was performed using the parametric Student t tests. The Mann–Whitney U test was used, however, to evaluate numerical variables with a skewed distribution, such as hemoglobin drop, hospitalization time. Proportions of categorical variables were analyzed using the chi-square or Fisher exact test; if the minimum expended count was less than 5, comparisons of categorical variables rate were performed by the Fisher exact test.

Results

All PCNL procedures were completed through a single percutaneous tract. Intercostal percutaneous access was needed in four patients who had upper caliceal stones. Tubeless PCNL was performed in five of the patients. Table 2 shows the comparison of perioperative and postoperative data. The average total operative time was significantly longer for the RIRS group. The minor complication rate for the RIRS group was 7.1% and 10.7% for the PCNL group according to the modified Clavien classification system.⁷ No major complications occurred in either group. Two patients presented with renal colic deriving from the passage of stone fragments, and all colicky patients in the RIRS group were treated conservatively. Furthermore, the stent-related complications were not seen in any patient who underwent RIRS. The mean total length of hospitalization was significantly shorter in the RIRS group (26.5±10.6 h per patient vs 60.0±28.8 h; P<0.0001). Second stage RIRS was performed in 17.8% of the patients, because of remaining residual stone fragments or poor visualization because of stone dusts.

Table 2.

Comparison of Outcomes of Retrograde Intrarenal Surgery and Percutaneous Nephrolithotomy in Elderly Patients

Parameters	RIRS group	PCNL group	P value
Mean total operative time per patient (min)	64.5±20.9	40.7±10.7	<0.0001
Mean fluoroscopy time (min)	1.8±0.8	4.2±2.4	<0.0001
Mean hospitalization time±SD (h)	26.5±10.6	60.0±28.8	<0.0001
Complications (n)			1.0
Blood transfusion requirement	0	2
Transient fever	0	1
Renal colic	2	0
Hemoglobin (g/dL)
Preoperative	12.4±0.2	13.4±1.6	0.008
Postoperative	12.3±1.0	12.0±1.0	0.45
Drop in hemoglobin level	0.6±2.2	1.4±1.3	<0.0001

RIRS=retrograde intrarenal surgery; PCNL=percutaneous nephrolithotomy; SD=standard deviation.

Stone-free rates after a single procedure were achieved in 82.1% for the RIRS and 92.8% for the PCNL group, respectively. A second flexible ureterorenoscopy procedure was needed for five patients in the RIRS group. Finally, stone-free rates during the third month of the follow-up period were 92.8% in the RIRS group and 96.4% in the PCNL group. Stone analysis was also obtained in the PCNL (67.8 %) and the RIRS (71.4 %) groups. Calcium oxalate was the most prevalent stone composition in both groups (PCNL group: 77.7%; RIRS group: 68.4%).

Discussion

Although PCNL is considered to be an effective and safe modality in the management of larger renal stones, major complications are reported in the current series.^4,8 Skolarikos and de la Rosette⁷ have reported that the frequency of major complications after PCNL was 0.9% to 4.7% for septicemia, 0.6% to 1.4% for renal hemorrhage necessitating intervention, 2.3% to 3.1% for pleural injury, and 0.2% to 0.8% for colonic injury. Modern flexible ureteroscopes, however, have smaller sizes but larger and more durable working channels and dual flexible capabilities. A considerable decrease in complication rates facilitated by technologic innovations in flexible ureteroscopes and holmium–yttrium-aluminum-garnet lasers has been reported.^9,10 In parallel with these technologic developments, recent studies showed that RIRS can be successfully applied for stones >2 cm.^11
–13

Changes in the cardiorespiratory reserve of elderly patients makes the patients less tolerant to certain stressors, such as bleeding or septic complications.¹⁴ Thus, the anesthetic risks for the elderly patient are more prevalent than for younger patients. Invasive treatments, such as PCNL, for elderly patients with stones have always been a matter of concern from the perspectives of the surgeon and the anesthetist. Therefore, the general health of the patient, along with stone size and location, should be taken into consideration during the evaluation of treatment alternatives in geriatric patients with renal stone(s).

As far as we know, the present study is the first investigation comparing the outcomes and morbidities of PCNL and RIRS in the geriatric age group. In the limited number of studies comparing RIRS and PCNL, similar stone-free rates were reported.^15
–17 Chung and associates¹⁵ evaluated the outcomes of 15 PCNL and 12 RIRS patients who were treated for the clearance of 1- to 2-cm renal calculi and reported that stone-free rates were 87% and 67% for the PCNL and RIRS groups, respectively.¹⁵ In a recent study, Bozkurt and colleagues¹⁷ retrospectively compared the outcomes of PCNL and RIRS in 79 patients with lower pole calculi with diameters of 15 to 20 mm. The authors concluded that RIRS is a good alternative to PCNL, with a stone-free rate of 89.2%.¹⁷

Our study demonstrates that RIRS can be performed safely and effectively for geriatric patients with moderate-sized kidney stones. The overall stone-free rates after a single stage procedure for the RIRS and PCNL groups in the present study were 82.1% and 92.8%, respectively. On the other hand, in the RIRS group, a second flexible ureterorenoscopy procedure was needed in 17.8% of the patients who underwent RIRS. Second stage RIRS is generally performed because of poor visualization, prolonged operative time, larger stone size, and patient or physician preference. Hyams and coworkers¹² published the outcome of a multi-institutional series of RIRS and laser lithotripsy for renal stones of 2 to 3 cm and reported residual stone fragments of 0 to 2 mm in 66% and <4 mm in 83% of patients. They treated 83% of patients with a single stage RIRS procedure. Second or more stages were required in 17% of patents in their series.¹² In another study, Breda and colleagues¹³ evaluated the efficacy of small diameter flexible ureteroscopy with laser lithotripsy for intrarenal calculi 20 to 25 mm in diameter and reported that overall stone-free after mean 2.3 procedures rate was 93.3%.

In the RIRS group, in addition to stone-free rates similar to those of PCNL, major complications, such as severe bleeding, ureteral avulsion, and perforation, were absent. Similar to previous series, two (7.1%) patients with renal colic in the RIRS group were referred to the hospital again and treated conservatively. Rehospitalization after RIRS can be related to passage of stone fragments and postoperative stent pain. On the other hand, the overall complication rate has been reported up to 83%, with a significant complication rate up to 8% in the PCNL literature.^3,4 Among complications, blood loss necessitating transfusion is one of the most important complications, because, rarely, hemorrhage cannot be controlled, and an angioembolization or nephrectomy is needed.^18–19 Severe bleeding necessitating blood transfusion was observed in 7.1% of patients who underwent PCNL in the present study.

Total operative time was longer in patients who were treated with RIRS compared with those in the PCNL group in the present study (64.5±20.9 and 40.7±10.7 min). We used semirigid ureteroscopy for visual assessment of the ureter in all patients. In fact, this maneuver contributes to the increase of RIRS operative time. Similar to our findings, Breda and associates²⁰ reported a mean operative time of 65.1 minutes (range 15–120 min) for the ureteroscopic management of renal stones between 13 and 36 mm.²⁰ Mariani²¹ treated with RIRS 16 patients with 17 renal calculi more than 4 cm in length and reported an average operative time of 49 minutes per stage for an average total operating time of 115 minutes per calculus. On the other hand, as one of the reasons for the increased demand for blood transfusions, operative times are especially important for patients undergoing PCNL.^18,22 Correlations, however, between outcomes as well as complications of RIRS and operative times should be investigated.

Generally, RIRS is considered to be a day-care outpatient procedure. In our series, although the patients were in the geriatric age group, after a mean total hospitalization stay of 26.5±10.6 hours, they were discharged. The mean operative time (60.0±28.8 hours) in the PCNL group was significantly longer, however. One of the most important reasons for this difference was the presence of nephrostomy tubes inserted for drainage. Akman and coworkers²³ emphasized that the presence of diabetes, a large stone burden, intercostal access, multiple accesses, impaired kidney function, and the use of the tubeless procedure affect the length of hospitalization. The surgeon's requirement that patients remain under their surveillance for a certain time might be another factor affecting the length of the hospitalization period.

This study has several limitations because of its retrospective design. First, the number of cases included is relatively limited. Second, the postoperative requirement for analgesics and pain score could not be evaluated. Third, stone analysis was not available in all patients. Prospective studies with larger patient populations investigating long-term outcomes including stone recurrence and cost-effectiveness are needed. Last, mini-PCNL was not used in the present study. Using mini-PCNL may be less traumatic in kidneys with nondilated calices and narrow infundibula, and it may reduce bleeding during PCNL.

Conclusion

RIRS has a low complication rate and stone-free rates that are comparable to those achieved with PCNL; RIRS may be an effective treatment alternative to PCNL in selected geriatric patients with a single, moderate-sized kidney stone. RIRS can decrease the incidence of PCNL-related comorbidities, such as longer hospital stays and a need for blood transfusions.

Footnotes

Disclosure Statement

No competing financial interests exist.

Abbreviations Used

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