Operating Times and Bleeding Complications in - SBU-MG

JOURNAL OF ENDOUROLOGY
Volume 25, Number 6, June 2011
ª Mary Ann Liebert, Inc.
Pp. 933–939
DOI: 10.1089/end.2010.0606
Operating Times and Bleeding Complications in Percutaneous
Nephrolithotomy: A Comparison of Tract Dilation Methods
in 5537 Patients in the Clinical Research Office
of the Endourological Society
Percutaneous Nephrolithotomy Global Study
Akito Yamaguchi, M.D.,1 Andreas Skolarikos, M.D.,2 Niels-Peter Noor Buchholz, M.D.,3
Gonzalo Bueno Chomón, M.D.,4 Michael Grasso, M.D.,5 Pietro Saba, M.D.,6 Stephen Nakada, M.D.,7
and Jean de la Rosette, M.D.,8 on behalf of the Clinical Research Office of the Endourological Society
Percutaneous Nephrolithotomy Study Group
Abstract
Purpose: The study investigated factors that affect operating times and bleeding complications associated with
percutaneous nephrolithotomy (PCNL) in the PCNL Global Study.
Patients and Methods: All patients who underwent PCNL for primary or secondary treatment of kidney stone
indications during the study period (November 2007–December 2009) were eligible for inclusion. PCNL procedures were performed according to local clinical guidelines and practices. Nephrostomy tract dilation was
performed using balloon dilation, metal telescopic dilation, or Amplatz serial dilation. Hematologic complications assessed included bleeding rates, transfusion rates, and preoperative and postoperative hematocrit values.
Results: The median operating time with balloon dilation (n = 2277) was significantly longer than with telescopic/
serial dilation (n = 3260) at 94.0 vs 60.0 minutes, respectively (P < 0.0001). In the balloon dilation group, there was
significantly more bleeding (9.4% vs 6.7%, respectively; P < 0.0001) and more transfusions (7.0% vs 4.9%, respectively; P = 0.001) compared with the telescopic/serial dilator group. Univariate analysis showed that the probability
of bleeding complications was higher with balloon vs telescopic/serial dilation (odds ratio [OR] 1.75; P = 0.0001) and
larger sheath size (OR 1.42; P = 0.0001). By multivariate analysis, sheath size but not dilation method was predictive
of bleeding complications. Other significant predictive factors included operating time, stone load, and caseload.
Conclusion: This study shows that in PCNL, factors that are associated with bleeding/transfusion include sheath
size, operating time, stone load, and caseload.
Introduction
T
he Clinical Research Office of the Endourological
Society (CROES) was established in 2008 as a subgroup of
the Endourological Society to provide a global collaborative
framework to facilitate dialogue and to support research in
endourology.1,2 An area of special interest of CROES is percutaneous nephrolithotomy (PCNL) for the treatment of renal
stones, and as such, centers that perform the procedure were
invited to participate in the PCNL Global Study. The study
was observational, and a database was established to collect
data on consecutively treated patients for a period of 1 year.
When the PCNL Global Study database closed in December
2009, it included information on more than 5800 patients from
96 centers in 26 countries.3,4 The primary objective of the
PCNL Global Study was to assess stone-free rates; numerous
secondary analyses are ongoing or complete, including a
comparison of methods used for nephrostomy tract dilation.
1
Department of Urology, Harasanshin General Hospital, Fukuoka, Japan.
Second Department of Urology, University of Athens, Athens, Greece.
3
Department of Urology, St. Bartholomew’s Hospital, London, United Kingdom.
4
Department of Urology, Hospital General Universitario Gregorio Marañón, Madrid, Spain.
5
Department of Urology, New York Medical College, New York, New York.
6
Department of Urology, Moriggia Pelascini Hospital, Gravedono, Italy.
7
Department of Urology Faculty, University of Wisconsin School of Medicine, Madison, Wisconsin.
8
Department of Urology, AMC University Hospital, Amsterdam, The Netherlands.
2
933
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YAMAGUCHI ET AL.
During PCNL, a large percutaneous tract into the kidney is
established using pneumatic dilation (balloon dilation), rigid
coaxial metal sheaths (passed over one another), or semirigid
plastic sheaths (sequentially performed) that are inserted
incrementally until the tract is dilated.5–8 More recently, a
single-step technique involving the use of an Amplatz serial
dilator over a metallic telescopic dilator (‘‘one-shot’’) has become accepted as a safe and effective technique.9–11 Balloon
dilation is generally thought to be associated with shorter
operating times and reduced radiation exposure than traditional multi-incremental methods, although balloon dilation
is the more expensive option.10,12,13
The initial PCNL Global Study analysis of nephrostomy
tract dilation methods highlighted some important regional
differences in the choice of dilator4; for example, balloon dilation was the method of choice in North America where cost
was not an issue, whereas in South America and Asia, telescopic/serial tract dilation was preferred. In Europe, however, neither method predominated. Apart from cost, factors
underlying the choice of dilator appeared to include obesity,
previous kidney stone procedures, and high stone load, with
balloon dilation favoring such patients.4
Complication rates in PCNL are reported from 29% to
83%,14–16 and in a recently completed PCNL Global Study
analysis, the overall complication rate was 15%, which
commonly involved bleeding.3 Balloon dilation appears to
be preferred in patients who are deemed to be at an increased
risk for complications,4 and balloon dilation is largely reported to have a better morbidity profile than metal telescopic dilation.12,17,18 Nonetheless, clinical studies and
retrospective reviews have also reported that balloon dilation has a similar morbidly profile as multi-incremental
methods.9,10,13
Contrary to previous reports, in the initial PCNL Global
Study analysis of dilation methods, bleeding complications
and transfusions were reported in 9.4% and 7.0% of patients,
respectively, with balloon dilation, compared with 6.7% and
4.9% of patients, respectively, with telescopic/serial dilation.4
Therefore, in follow-up to the initial analysis of dilation
methods, we conducted further analyses of the PCNL Global
Study dataset to investigate operating times, hematologic
safety, and risk factors for complications with balloon vs
telescopic/serial dilators.
Patients and Methods
Data collection
This secondary analysis is part of a series from the CROES
PCNL Global Study and was conducted to assess bleeding
complications and operating times with balloon dilation
compared with telescopic/serial dilation methods. The description of centers included in the study and data collection
methods have been described previously.3 To reiterate, a
steering committee of global experts in PCNL treatment was
invited by the CROES council to direct the study. The target
was to enroll 100 centers worldwide, including smaller centers, which performed < 25 procedures a year, and ‘‘high
volume’’ centers, which performed > 100 procedures annually. Centers invited to participate were members of the Society of Endourology or were considered to have high
expertise in the surgical field.
Electronic databases were made available to participating
centers, and data were sent encrypted to the headquarters of
CROES. Institutional Review Board approval was obtained at
participating centers, if needed. The lead investigator at each
center coordinated data collection and submitted regular
updates to the central database. Each center provided data for
consecutive PCNL patients for a study period of 1 year
starting from the date of inclusion of the first patient. The first
patient was entered into the database in November 2007, and
the database was closed in December 2009.
Patients and procedures
There were no specific exclusion criteria, and all patients
who underwent PCNL for the primary or secondary treatment of kidney stone indications during the study period
were eligible for inclusion. PCNL procedures were performed
according to local clinical guidelines and practices. A description of kidney stone indications and PCNL procedures is
in the first PCNL Global Study analysis reported by de la
Rosette and associates.3 Nephrostomy tract dilation was
performed using balloon dilation, metal telescopic dilation, or
Amplatz serial dilation and is described in a previous publication.4
Assessments
The variables included in the analysis were operating time,
the incidence of bleeding, the number of transfusions, and
preoperative and postoperative hemoglobin and hematocrit
levels. Preoperative factors that were analyzed were body
mass index (BMI), stone size, and the use of anticoagulation
therapy. In patients receiving anticoagulation therapy, a
subanalysis was performed. For each surgical procedure,
operating time was recorded as the time from the first puncture to the completion of the stone removal. Outcomes were
assessed according to Amplatz sheath size, defined as small
(size 18F and below), medium (size 24F to 26F), large (sizes
27F, 28F, and 30F), and largest (sizes 32F, 33F, and 34F). The
study centers were classified according to the volume of
procedures performed in the study year; ie, caseload (low
< 25; medium 25–100; high > 100), and according to the dilation method used (balloon only, telescopic/serial only; centers with 10% of patients dilated with either method were
Table 1. Bleeding Complications and Operating Times
Characteristic
Bleeding
Drop in hematocrit (mean/median)
Blood transfusion
Median operating time (min)
Balloon dilators
n = 2277
Telescopic/serial dilators
n = 3260
P value
9.4%
4.48/4.50
7.0%
94.0
6.7%
2.48/2.40
4.9%
60.0
< 0.0001
< 0.0001
0.001
< 0.0001
CROES PCNL STUDY
935
Table 2. Bleeding Complications in Patients by Perioperative Anticoagulation Therapy Subgroup
Received anticoagulation therapy
n = 313
Bleeding rate
Transfusion rate
Median Hb drop
No anticoagulation therapy
n = 5224
Balloon
Telescopic/serial
P value
Balloon
Telescopic/serial
P value
10.9%
8.3%
4.8
7.8%
6.8%
3.0
0.476
0.721
0.03
9.2%
6.9%
4.50
6.6%
4.8%
2.40
0.001
0.002
< 0.0001
Hb = hemoglobin.
classed as ‘‘mixed’’). To control for patient selection bias,
outcomes were also assessed in a subgroup of patients who
were at a low risk of bleeding. The low-risk subgroup included patients aged 30 to 60 years, with no history of anticoagulation therapy, and who had had lower-pole punctures.
Statistical analyses
Patients were grouped according to dilation method: Balloon dilation or telescopic/serial dilation. Continuous variables were analyzed using a Student t test (parametric) or a
Mann-Whitney U test (nonparametric), and categorical variables were analyzed using the Pearson chi square test. Univariate and multivariate regression analyses for risk of
bleeding/transfusion examined the following factors: Operating time, stone load, anticoagulant use, caseload, BMI,
sheath size, and dilation method. Results of the univariate and
multivariate logistic regression analyses were provided as
OR, with 95% confidence intervals (CI). A P value of < 0.05
was considered significant. The data were analyzed with SPSS
version 16.0. The statistical analysis was supervised by a senior expert in the field.
Results
Patients
From a total of 5803 patients included in the Global PCNL
database, 266 patients were excluded from the analysis because no information about the method of dilation was
available. Of the 5537 patients included in the current analysis, 2277 (41.1%) were in the balloon dilation group and 3260
(58.9%) in the telescopic/serial dilation group. Patient characteristics of the two groups are as described previously.3,4
Bleeding complications
Bleeding was reported in 9.4% of patients with balloon dilation compared with 6.7% with telescopic/serial dilation
(P < 0.0001; Table 1). Balloon dilation was also associated with
significantly more transfusions (P = 0.001) and greater drops in
hematocrit level (P < 0.0001) than telescopic/serial dilation, as
well as significantly longer median operating times (P < 0.0001;
Table 1). A small proportion of the total cohort (313/5537;
5.7%) received perioperative anticoagulation therapy (including calcium carbasalate and warfarin), and in this subpopulation, bleeding and transfusion rates were similar in the
balloon and telescopic/serial dilator groups (Table 2). In the
5224 patients who did not receive perioperative anticoagulation therapy, in the balloon dilator group, there was
significantly more bleeding (9.2% vs 6.6%, P = 0.001), and significantly more transfusions (6.9% vs 4.8%; P = 0.002) than in
the telescopic/serial dilator group (Table 2). There was a trend
for slightly higher rates of bleeding, transfusions, and drops in
hemoglobin level for patients who received anticoagulation
therapy vs those who did not (Table 2).
Low-risk subgroup analysis
A total of 1890 patients were included in the low-risk
subgroup. Bleeding was reported in 10% of patients with
balloon dilation and 5.6% of patients with telescopic/serial
dilation, and transfusion rates showed a similar trend (6.1% vs
3.0%). The median operating times were 90 and 60 minutes
with balloon dilation and telescopic/serial dilation, respectively.
Center and sheath size
A total of 1274 patients were treated in balloon dilation
only centers, 953 patients in telescopic/serial dilation only
centers, and 1124 patients in centers classified as ‘‘mixed’’
( > 10% of patients received either method). Those centers
with < 0% of either method were excluded from this specific
analysis. Balloon dilator only centers had similar bleeding
rates but higher transfusion rates and longer median operating times than telescopic/serial only centers (Table 3). Mixed
centers had higher rates of bleeding and transfusions than
centers using a single method (Table 3).
In low-volume centers, median operating times with balloon vs telescopic/serial dilation were 105 minutes vs 108
minutes, respectively, and in medium-volume centers were 98
minutes vs 80 minutes, respectively (Table 4). The difference
Table 3. Bleeding Complications
and Operating Times by Center
Classified According to the Dilation Method
Balloon dilation Mixed
only centers
centers
n = 1274
n = 1124
Bleeding rate
Transfusion rate
Median operating
time (min)
9.1%
7.1%
98
10.7%
8.3%
90
Telescopic/serial
dilation only
centers
n = 953
9.6%
4.2%
65
Mixed centers defined as those in which 10% of procedures
performed by either method; n refers to the number of procedures
performed.
936
YAMAGUCHI ET AL.
Table 4. Bleeding Complications and Median Operating Times by Study Center Volume
Low volume
( < 25 procedures/y)
High volume
( > 100 procedures/y)
in mean operating time between procedures was much
greater in high-volume centers compared with the differences
reported in low- and medium-volume centers, at 90 minutes
for balloon dilation vs 55 minutes for telescopic/serial dilation
(Table 4). Another interesting trend was the risk of bleeding/
transfusion with the balloon increased from low- to highvolume centers while the risk of bleeding/transfusion with
telescopic dilators decreased from low- to high-volume centers.
Sheath size was associated with increased transfusion rates
(chi square, 38.02; P < 0.0001), with transfusion rates of 1.1%
for the smallest sheath and 12.0% for the largest sheath
(Table 5). A large sheath (27F, 28F, and 30F) was used in the
majority of patients (3533/5214; 68%) and was associated
with a transfusion rate of 5.9% (Table 5).
Predictors of bleeding complications
Univariate logistic regression showed that balloon vs telescopic/serial dilation was associated with a higher rate of
bleeding, with an OR of 1.75 (95% CI, 1.39–2.19; P = 0.0001)
(Table 6). Other factors that were predictive of bleeding
complications were operating time, stone load, caseload, and
sheath size (Table 6). BMI and anticoagulation therapy were
not associated with an increased risk of bleeding complications. Multivariate logistic regression showed that the dilation
method was not associated with increased bleeding rates (OR,
1.18; 95% CI, 0.91–1.52; P = 0.2) (Table 7). The multivariate
analysis showed that factors predictive of bleeding complications were operating time (P = 0.0001), stone load
(P = 0.002), caseload (P = 0.001), and sheath size (P = 0.01)
(Table 7). Because sheath size was a strong predictive factor,
the relationship between method of dilation and sheath size
was examined more closely. With the exception of the largest
sheaths that were used in the balloon dilation group, bleeding
Table 5. Transfusion Rate
According to Amplatz Sheath Size
Small (18F and below)
Medium (24F and 26 F)
Large (27F, 28F, and 30F)
Largest (32F, 33F, and 34F)
Telescopic/serial dilation
n = 3260
7.9%
4.8%
105
8.8%
4.5%
98
10.4%
10.1%
90
12.9%
8.1%
108
11.6%
4.5%
80
3.6%
4.8%
55
Bleeding rate
Blood transfusion rate
Operating time (min)
Bleeding rate
Blood transfusion rate
Operating time (min)
Bleeding rate
Blood transfusion rate
Operating time (min)
Medium volume
(25–100 procedures/y)
Sheath size
Balloon dilation
n = 2277
No. of
patients
271
1039
3533
371
Blood transfusion
(n [%])
3
50
208
45
Blood transfusion status reported for 5214 patients.
(1.1%)
(4.8%)
(5.9%)
(12.1%)
and transfusions tended to increase with increasing size of
sheath (Table 8). Use of medium and large sheaths was associated with higher rates of bleeding and transfusion with
balloon dilation than with telescopic dilation.
Discussion
Percutaneous tract dilation is a major component of PCNL
and is performed using a balloon dilator, metal telescopic
dilator, Amplatz serial dilator, or an Amplatz dilator over a
metallic telescopic dilator (one-shot). Each dilation method
has pros and cons regarding operating times, patient selection, complications, and cost, and the method used is often
determined by surgeon preference and local availability. In
the present analysis of the PCNL Global Study, it was observed that median operating time was significantly shorter
with telescopic/serial dilation at 60 minutes vs 94 minutes for
balloon dilation. This was an unexpected finding, because
previous studies suggest that operating time and fluoroscopic
exposure is shorter with balloon vs telescopic dilation and
similar for balloon vs serial dilation. Frattinni and associates10
conducted a clinical study of 78 consecutive patients and
Table 6. Univariate Regression Analysis
of Procedural and Patient Characteristics
as Predictors of Bleeding or Transfusions
Operating time
(10 min interval)
Stone load
(50 mm2 interval)
Anticoagulation
therapy
Caseload (center
volume low-mid-high)
BMI classa
Sheath category
(small, medium,
large, largest)
Dilation method
(telescopic/serial = 1.0)
Odds ratio for bleeding
complications
(95% confidence interval)
P
value
1.107 (1.082–1.134)
0.0001
1.049 (1.035–1.068)
0.0001
1.449 (0.865–2.427)
0.158
0.658 (0.567–0.764)
0.0001
1.008 (0.893–1.138)
1.427 (1.205–1.688)
0.892
0.0001
1.751 (1.397–2.193)
0.0001
a
World Health Organization body mass index (BMI) class:
Underweight ( < 18.49); normal (18.5–24.99); overweight (25.0–
29.99); obese ( ‡ 30.0).
CROES PCNL STUDY
937
Table 7. Multivariate Regression Analysis
of Procedural and Patient Characteristics
as Predictors of Bleeding or Transfusions
Operating time
(10 min interval)
Stone load
(50 mm2 interval)
Anticoagulation
therapy
Caseload (center
volume low-mid-high)
Sheath category
(small, medium,
large, largest)
Dilation method
(telescopic/serial = 1.0)
Odds ratio
for bleeding complications
(95% confidence interval)
P value
1.066 (1.039–1.094)
0.0001
1.029 (1.011–1.048)
0.002
1.261 (0.794–2.003)
0.327
0.721 (0.597–0.870)
0.001
1.322 (1.068–1.637)
0.01
1.182 (0.914–1.528)
0.201
showed that mean (standard deviation [SD]) radiation exposure with telescopic, balloon, and one-shot dilation was 310
(216), 179 (90), and 262 (173) seconds, respectively. In a retrospective review of 143 patients reported by Davidoff and
Bellman,17 surgery time was similar with the balloon vs
Amplatz dilation at mean (SD) times of 108.8 (41.4) and 118.9
(46.6) minutes, respectively. Additional reports come from
Safak and colleagues12 who compared 95 balloon dilation
procedures with a retrospective group of 30 consecutive
Amplatz dilator procedures and reported mean (SD) operating times of 106.8 (41.4) vs 116.4 (23.7) minutes, respectively.
In a review of 235 procedures, Gonen and coworkers19 reported that mean (SD) operating times were similar with
Amplatz and balloon dilation at 86.3 (41.2) vs 85.7 (43.2)
minutes, respectively.
In the PCNL Global Study, the trend for shorter operating
times with telescopic/serial dilators was not seen in lowvolume centers, where median operating times in the two
groups were similar at 105 minutes with balloon and 108
minutes with telescopic/serial dilation. In high-volume centers, however, the trend was pronounced, and the median
operating time for procedures using telescopic/serial dilation
was 55 minutes compared with 90 minutes with balloon dilation. This suggests that in centers performing > 100 procedures/year, surgeon experience can reduce the operating
times with telescopic/serial methods to a greater degree than
that achieved with balloon dilators.
Bleeding and blood transfusions are common complications of PCNL, and balloon dilation is generally considered to
have a better hematologic morbidity profile than the other
dilation methods. Indeed, because balloon dilation is radial,
there is no risk of forward perforation, but with multi-incremental methods, there is a risk of perforation of any structure
ahead or structures surrounding the tract. In the PCNL Global
Study, however, bleeding was significantly higher with balloon at 9.4% compared with telescopic/serial dilation at 6.7%.
A similar trend was seen for transfusions, which were significantly more common with balloon than telescopic/serial
dilation at 7.0% and 4.9%, respectively. In the analysis including patients aged 30 to 60 years, with no anticoagulation
therapy, and lower-pole punctures (ie, potential patient selection bias removed), balloon dilation was again associated
with higher rates of bleeding and transfusions than telescopic/
serial dilation.
Contrary to our results, previous studies have reported that
each dilation method has a similar morbidity profile, or that
balloon dilation is favorable compared with Amplatz serial
dilation. In the clinical study by Frattinni and associates,10
telescopic, balloon, and one-shot dilation had similar hematologic safety profiles, and in the randomized study reported
by Falahatkar and coworkers,9 telescopic and one-shot dilation had similar complication rates. In a review by Wezel and
colleagues,13 although telescopic dilation was associated with
significantly longer mean (SD) hospital stays than balloon
dilation (7 [5] vs 5 [4] d, respectively), the methods had similar
hematologic morbidity, and in the studies by Gonan and associates19 (Amplatz vs balloon dilation) and Amjadi and colleagues11 (one-shot vs telescopic dilation), the methods had
comparable complication profiles. Other studies, however,
have reported that balloon dilation has a better safety profile
than Amplatz dilation for transfusion rates (10 and 25 transfusions, respectively)17 and bleeding (13% and 16.6%, respectively).12
In the PCNL Global Study, center type by patient volume
appeared to influence the rate of bleeding complications and
transfusions, with higher rates in high- vs low-volume centers
in the balloon dilator group. This may be because high-volume/more experienced centers have a higher proportion of
difficult cases than less experienced, low-volume centers. The
opposite is seen, however, with telescopic/serial dilation with
lower transfusion rates in the high- vs low-volume centers. It
is possible that procedures in ‘‘difficult to treat’’ patients,
which may be more frequent in high-volume centers, are more
likely to involve balloon than telescopic/serial dilation. This is
supported by the previous PCNL Global Study analysis,
which showed balloon dilation was more frequent than telescopic/serial dilation in patients with staghorn stones.4 Indeed, the multivariate analysis showed that caseload was
predictive of bleeding and transfusions overall, again
suggesting that higher volume centers may have a higher
Table 8. Frequency of Bleeding and Blood Transfusion According to Method of Dilatation and Sheath Size
Bleeding
Sheath size
Small ( £ 18F) N = 271
Medium (24F, 26F) N = 1039
Large (27F, 28F, 30F) N = 3533
Largest (32–34F) N = 371
Balloon n/N (%)
0/37
9/107
197/1978
2/95
(0%)
(8.4%)
(10.0%)
(2.1%)
Blood transfusion
Telescopic/serial n/N (%)
11/234
44/932
109/1555
31/276
(4.7%)
(4.7%)
(7.0%)
(11.2%)
Balloon n/N (%)
0/37
6/107
143/1978
6/95
(0%)
(5.6%)
(7.2%)
(6.3%)
Telescopic/serial n/N (%)
3/234
45/932
63/1555
38/276
(1.3%)
(4.8%)
(4.1%)
(13.8%)
938
proportion of difficult to treat cases. Furthermore, in centers
that used telescopic/serial dilation only, the transfusion rate
was 4.2%, and in centers that used balloon dilation only, it
was 7.1%, compared with 8.3% in centers using both methods.
These findings for balloon vs telescopic/serial dilation by
center volume may be associated with surgeon experience,
meaning that bleeding complications are reduced with telescopic/serial dilation in high-volume centers or may again
suggest that the use of balloon dilation is more common in
high-risk patients.
Factors that were reported previously to be predictive of
blood loss in PCNL include stone type, diabetes, and stone
surface area.18 In the current univariate and multivariate analyses, operating time, stone load, caseload, and sheath size
were significant predictors of bleeding and transfusions. In a
previous PCNL Global Study analysis, BMI appeared to influence the choice of dilation method, with balloon dilation
favored in obese patients. Indeed, it has been suggested that
obesity increases the technical difficulty of PCNL, and this
may increase the risk of complications, with some studies
reporting a negative impact on complication rates20–23 and
others reporting that BMI does not influence outcomes.15,21–26
In the current univariate analysis, BMI and BMI by World
Health Organization classifications were not associated with
an increased risk of bleeding and transfusions.
Use of Amplatz serial dilation vs balloon dilation is reported to be a risk factor for bleeding complications.18 In the
present study, univariate logistic regression showed that
using balloon dilation significantly increased the risk of
bleeding complication compared with telescopic/serial dilation with an OR of 1.75 (95% CI, 1.39–2.19), although dilation method was not shown to increase risk in the
multivariate analysis. Further analysis revealed that smaller
sheaths were used more frequently in the telescopic/serial
dilator group. Moreover, in both the medium and large
sheath groups, the rates of bleeding and blood transfusion
were higher after balloon dilation than after telescopic/
serial dilation. When more variables, such as operating time,
caseload, history of anticoagulant use, or stone load, were
included in the multivariate model, however, the method of
dilation was not a significant predictor. It seems safe to
conclude that because these factors may not be easily modifiable, the method of dilation and sheath size may be the
only factors that provide the clinician with choice in the
clinical approach to PCNL.
Although the results of the PCNL Study suggest that
telescopic/serial dilation methods were less likely to cause
bleeding than balloon dilation, this may be associated with
factors that were unrelated to the procedure. For example,
surgeons reporting the use of telescopic/serial dilators may
have had longer experience, performed better punctures, or
performed better overall, compared with those using balloon dilators. Further analyses are therefore ongoing to investigate these possibilities. Nonetheless, the results of this
study offer an important insight into complications and dilation methods.
Conclusion
Telescopic/serial dilation and smaller sheath size are associated with shorter operating times than balloon dilation
and larger sheath size. Factors predictive of bleeding com-
YAMAGUCHI ET AL.
plications include stone load, caseload, sheath size, and operating time. These analyses, however, do not take into
account the experience of the surgeon, which will always influence outcomes.
Acknowledgment
The PCNL Global Study was supported by an unrestricted
educational grant from Olympus. Prof. dr. A.H. Zwinderman
is consulted to overlook the statistical aspects of the CROES
studies.
Disclosure Statement
No competing financial interests exist.
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Address correspondence to:
Jean J.M.C.H. de la Rosette, M.D.
Department of Urology
AMC University Hospital
Meibergdreef 9
1105 AZ Amsterdam Z-O
The Netherlands
E-mail: [email protected]
Abbreviations Used
BMI ¼ body mass index
CI ¼ confidence interval
CROES ¼ Clinical Research Office
of the Endourological Society
OR ¼ odds ratio
PCNL ¼ percutaneous nephrolithotomy
SD ¼ standard deviation