JOURNAL OF ENDOUROLOGY Volume 28, Number 11, November 2014 ª Mary Ann Liebert, Inc. Pp. 1304–1307 DOI: 10.1089/end.2014.0465
Contemporary Practice Patterns Associated with Percutaneous Nephrolithotomy Among Certifying Urologists Gautam Jayram, MD, and Brian R. Matlaga, MD, MPH
Abstract
Background and Purpose: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for patients with complex stone burdens. We performed a study to assess the effect of urologist-specific parameters on the use of PCNL—both the access component of the procedure as well as the stone removal. We also examined trends in PCNL utilization over time. Methods: We analyzed self-reported 6-month case logs submitted to The American Board of Urology (ABU) for urologists who certified or recertified between 2004 and 2013. Surgeons performing PCNL were identified by Current Procedural Terminology coding. Urologist-specific data, including fellowship training, practice type, and practice population, were used to further stratify this cohort. Trends were examined over the study period. Results: A total of 7278 urologists submitted case logs to the ABU between 2004 and 2013. The median ages of the initial certification group, first recertification group, and second recertification group were 36.0, 43.7, and 53 years, respectively. A greater proportion of newly certified urologists performed PCNL (53%) compared with urologists in the first (41%) and second (29%) recertification groups; initially certified urologists were also more likely to be high volume ( > 10) PCNL surgeons. Urologists with fellowship training were more likely to use PCNL (66%) and be high-volume surgeons (26.4%). PCNL utilization increased significantly during the study period, with 1330 procedures performed in 2004 and 2888 procedures performed in 2012 (117% increase). Conclusions: Younger and fellowship-trained urologists are the primary users of PCNL; the majority of senior urologists do not perform this operation. Overall, the use of PCNL and urologist-directed access has increased in the previous decade.
Introduction
P
ercutaneous nephrolithotomy (PCNL) is the standard treatment for patients with complex, large-volume upper tract calculi. Recent population-based studies have demonstrated a marked increase in the utilization of PCNL over the last 15 years.1,2 This comes despite significant advances in ureteroscopic technology and efficacy. In line with this, a recent Canadian study demonstrated a temporal paradigm shift in the use of extracorporeal shockwave lithotripsy (SWL) and ureteroscopy (URS) over the past 20 years, with reciprocal changes in use between the two modalities over time.3 Multiple reasons are plausible for a sustained rise in the use of PCNL: Increases in stone prevalence, improvements in intracorporeal lithotripters, and refinements of crosssectional imaging that facilitate the operative approach. Provider-specific factors—training, surgeon age/experience, and practice setting may also contribute. Our group has
previously shown provider-specific attributes affect how upper tract calculi are treated, with decreasing use of URS among more senior urologists.4 In 2005, the American Board of Urology (ABU) mandated all urologists seeking certification to submit operative case logs from a continuous 6-month period in their practice. We performed a study using these data to better understand contemporary trends in the utilization of PCNL, urologistspecific access, as well as provider-specific factors and their overall relationship to PCNL utilization. Methods
After 1985, certification given by the ABU for urologists must be renewed every 10 years. After 2005, candidates applying to the ABU for initial certification or recertification must submit electronic surgical practice logs as one component of their application. This case log represents 6 consecutive months of surgical practice chosen from an 18-month
James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland.
1304
PCNL PRACTICE PATTERNS
1305
period preceding application submission. Diagnoses are recorded in the practice log according to the International Statistical Classification of Diseases and Related Health Problems (ICD-9). Surgical procedures are classified by Current Procedural Terminology (CPT) code numbers. Patient-specific data in these logs are minimal (age and sex). Provider-specific data are more readily available, including practice type, practice population, candidate fellowship training, and overall case volume. No individual case information or outcome data were available. We analyzed these self-reported 6-month case logs from urologists who certified or recertified between 2004 and 2013. This time interval allowed us to theoretically capture every certifying urologist in the United States. Surgeons with duplicate records were excluded. Surgeons who performed PCNL were identified by CPT coding: 50080 and 50081; percutaneous access was identified by CPT 50395. Urologistspecific data, including fellowship training, practice type, and practice population, were used to further stratify the cohort performing these procedures. Trends were examined over the study period. For the purposes of our analysis, high-volume practitioners were defined as those who performed > 10 PCNLs per submitted practice log. Results
A total of 7278 urologists submitted case logs to the ABU between 2004 and 2013. Table 1 summarizes demographic and provider-specific factors for the entire cohort. All three certification groups (initial, first, and second) were similarly represented. The median ages of the initial certification group, first recertification group, and second recertification group were 36.0, 43.7 and 53 years, respectively; 22% and 5% of the cohort had any fellowship training and endourology/ stone training, respectively. The majority of urologists submitting case logs (62%) were in a private practice setting; 38% of all urologists practiced in large, urban settings ( > 1,000,000 persons). Based on submitted case logs, 41% of all urologists did not perform any PCNL during their study period. Furthermore, 6% of certifying urologists were considered highvolume PCNL performers, defined as > 10 PCNL/case log.
Table 1. Demographics of Study Cohort Urologists submitting logs Initial certification 1st recertification 2nd recertification Median age Initial certification 1st recertification 2nd recertification Fellowship training Stones Nonstones Practice setting Private Academic Hybrid Did not perform PCNL > 10 PCNL
FIG. 1. Temporal trends in percutaneous nephrolithotomy (PCNL) and urologist-performed access. Figure 1 demonstrates the temporal trend of PCNL utilization as well as urologist-directed access. In 2004, a total of 1330 PCNL procedures were performed, and in 2013, that number had increased to 2888, a 117% increase over 10 years. Urologist-directed access concordantly increased over time, with 14.5% of PCNL cases utilizing urologist access in 2004 and 20.4% in 2012, a 29% increase. Certification status (initial, first, or second) did not correlate with urologist access. Figures 2 and 3 demonstrate the utilization of PCNL based on urologist age (certification status). Although use of PCNL has increased over time among all urologists, initially certifying urologists perform more PCNLs than older urologists; 53% of initially certifying practitioners performed any PCNL procedures compared with 29% among the most senior (second recertification) group. Along with this, initially certified urologists comprised the largest percentage of all high-volume PCNL performers. Figure 4 provides a similar analysis with regard to fellowship training status. Urologists fellowship trained in stones were much more likely to utilize PCNL (66%) and be high-volume PCNL surgeons (26%). Academic practices
7278 2373 (33) 2644 (36) 2261 (31) 44.1 yrs 36 43.7 53 1578 (22) 375 (5) 1193 (17) 4497 2223 558 2946 464
(62) (31 (7) (41) (6)
FIG. 2. Temporal trends in percutaneous nephrolithotomy (PCNL) utilization by certification cohort.
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FIG. 3. Utilization of percutaneous nephrolithotomy based on urologist certification cohort. contained a higher proportion of high-volume PCNL surgeons (10%) compared with urologists in private or hybrid practices (5%); 7% of urologists in heavily populated areas ( > 1,000,000) were high-volume surgeons, compared with 5.6% and 4.6% of surgeons in medium size and small practice settings, respectively. Discussion
PCNL is the standard treatment for patients with complex or large-volume upper urinary tract calculi. Although ureteroscopic technology has progressed, recent data suggest that the utilization of URS and SWL has declined for patients with large calculi, whereas that of PCNL is steadily increasing.5 Ghani and associates5 abstracted data from the Nationwide Inpatient Sample (NIS) from 1999 to 2009 and found the number of PCNLs performed annually increased by
FIG. 4. Utilization of percutaneous nephrolithotomy based on fellowship training (FT).
JAYRAM AND MATLAGA
47% during this period. These findings are consistent with that of Morris and colleagues,2 who used the same database from 1998 to 2002, where PCNL utilization more than doubled from 1.2 per 100,000 U.S. residents to 2.5, a greater than 100% increase over that period. This trend does not appear to be a global one, though, because recent analyses from Canada, Australia, and the United Kingdom suggest PCNL utilization in those regions has remained stable or even slightly declining while endoscopic interventions for stone disease continue to climb.3,6–8 Our study, using ABU selfreported case logs to determine the utilization of PCNL among certifying urologists, confirms significant increase in the use of PCNL and also analyzes provider-specific factors responsible for this phenomenon. We have previously used ABU log data to evaluate trends in the management of upper urinary tract calculi.4 In this article, we found that initially certifying urologists used URS in their management of upper tract stones significantly more than older urologists, who tended to use SWL. The current study focuses on PCNL-specific trends, and augments these findings—PCNL is much more frequently performed by younger urologists, and the gap is especially wide between initially certifying (youngest) and second recertification groups (oldest). Younger urologists have likely had greater access to stone disease given increasing prevalence of urolithiasis and better detection methods.9 Furthermore, significant progress in endoscopic techniques as well as advances in PCNL safety, efficacy, and intracorporeal lithotripters likely have allowed many younger urologists greater facility and comfort with the procedure. Certification status did not correlate with urologistdirected access. Based on CPT coding, urologists obtained their own access in approximately 21% of PCNLs performed in 2013. Lee and coworkers10 performed a survey study of urologists and demonstrated significantly more urologists who had residency training in obtaining access performed PCNL and continued to get their own access in practice. This is consistent with our findings regarding fellowship training in stones, because these practitioners were much more likely to perform PCNL and be high-volume PCNL surgeons. Practice setting also was found to be associated with PCNL use in our study. Providers in academic and heavily populated areas tended to perform PCNL and be high-volume PCNL surgeons more frequently than providers in rural and low population density areas. This finding was previously reported by Morris and associates2 from their NIS study, where they showed the majority of PCNLs were being performed at urban teaching hospitals, and PCNLs performed at low PCNL volume or low-discharge volume PCNL carried an increased likelihood of mortality. Although ABU case log data are independently reviewed and validated, the log itself is self-reported and may contain provider bias. For example, it is not known how reliably urologist-directed access is captured by CPT code 50395. The overall accuracy of the dataset, however, is supported by the relative consistency of data from year to year within the certifying cohorts. Furthermore, data regarding case outcomes based on provider-specific factors, a potentially insightful metric, were not available. The time span used for our study was designed to attempt to capture every practicing urologist in the United States, further adding to the credibility of the data.
PCNL PRACTICE PATTERNS Conclusions
Based on self-reported ABU case logs, the utilization of PCNL and urologist-directed access has increased significantly over the past decade. Younger and fellowship-trained urologists are the primary users of PCNL, and the majority of senior urologists do not perform this operation. High-volume PCNL surgeons appear to be concentrated in academic and heavily populated practice settings. Although the incidence of urolithiasis is increasing, provider-specific factors impact the utilization of PCNL. Our findings can serve to inform future discussions on the regionalization of specialized urologic care. Acknowledgment
This research publication was made possible by support from Mr. and Mrs. Jerry and Helen Stephens. Disclosure Statement
Dr. Matlaga is a consultant for Boston Scientific. No competing financial interests exist for Dr. Jayram. References
1. Ghani KR, Sammon JD, Bhojani N, et al. Trends in percutaneous nephrolithotomy use and outcomes in the United States. J Urol 2013;190:558–564. 2. Morris DS, Wei JT, Taub DA, et al. Temporal trends in the use of percutaneous nephrolithotomy. J Urol 2006;175: 1731–1736. 3. Ordon M, Urbach D, Mamdani M et al. The surgical management of kidney stone disease: A population-based time series analysis. J Urol 2014. Epub before print. 4. Matlaga BR; American Board of Urology. Contemporary surgical management of upper urinary tract calculi. J Urol 2009;181:2152–2156.
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5. Ghani KR, Sammon JK, Karakiewicz PI, et al. Trends in surgery for upper urinary tract calculi in the USA using the Nationwide Inpatient Sample: 1999–2009. BJU Int 2013; 112:224–230. 6. Lee MC, Bariol SV. Evolution of stone management in Australia. BJU Int 2011;108(suppl 2):29–33. 7. Armitage JN, Withington J, van der Meulen J, et al. Percutaneous nephrolithotomy in England: Practice and outcomes described in the Hospital Episode Statistics database. BJU Int 2014;113:777–782. 8. Armitage JN, Irving SO, Burgess NA; British Association of Urological Surgeons Section of Endourology. Percutaneous nephrolithotomy in the United Kingdom: Results of a prosecptive data registry. Eur Urol 2012;61:1188–1193. 9. Scales CD Jr, Smith AC, Hanley JM, et al. Prevalence of kidney stones in the United States. Eur Urol 2012;62: 160–165. 10. Lee CL, Anderson JK, Monga M. Residency training in percutaneous renal access: Does it affect urological practice? J Urol 2004;171:592–595.
Address correspondence to: Brian R. Matlaga, MD, MPH 600 North Wolfe Street Park 221 Baltimore, MD 21287 E-mail: [email protected]
Abbreviations Used ABU ¼ American Board of Urology PCNL ¼ percutaneous nephrolithotomy SWL ¼ shockwave lithotripsy URS ¼ ureteroscopy
Contemporary Practice Patterns Associated with Percutaneous Nephrolithotomy Among Certifying Urologists Gautam Jayram, MD, and Brian R. Matlaga, MD, MPH
Abstract
Background and Purpose: Percutaneous nephrolithotomy (PCNL) is the treatment of choice for patients with complex stone burdens. We performed a study to assess the effect of urologist-specific parameters on the use of PCNL—both the access component of the procedure as well as the stone removal. We also examined trends in PCNL utilization over time. Methods: We analyzed self-reported 6-month case logs submitted to The American Board of Urology (ABU) for urologists who certified or recertified between 2004 and 2013. Surgeons performing PCNL were identified by Current Procedural Terminology coding. Urologist-specific data, including fellowship training, practice type, and practice population, were used to further stratify this cohort. Trends were examined over the study period. Results: A total of 7278 urologists submitted case logs to the ABU between 2004 and 2013. The median ages of the initial certification group, first recertification group, and second recertification group were 36.0, 43.7, and 53 years, respectively. A greater proportion of newly certified urologists performed PCNL (53%) compared with urologists in the first (41%) and second (29%) recertification groups; initially certified urologists were also more likely to be high volume ( > 10) PCNL surgeons. Urologists with fellowship training were more likely to use PCNL (66%) and be high-volume surgeons (26.4%). PCNL utilization increased significantly during the study period, with 1330 procedures performed in 2004 and 2888 procedures performed in 2012 (117% increase). Conclusions: Younger and fellowship-trained urologists are the primary users of PCNL; the majority of senior urologists do not perform this operation. Overall, the use of PCNL and urologist-directed access has increased in the previous decade.
Introduction
P
ercutaneous nephrolithotomy (PCNL) is the standard treatment for patients with complex, large-volume upper tract calculi. Recent population-based studies have demonstrated a marked increase in the utilization of PCNL over the last 15 years.1,2 This comes despite significant advances in ureteroscopic technology and efficacy. In line with this, a recent Canadian study demonstrated a temporal paradigm shift in the use of extracorporeal shockwave lithotripsy (SWL) and ureteroscopy (URS) over the past 20 years, with reciprocal changes in use between the two modalities over time.3 Multiple reasons are plausible for a sustained rise in the use of PCNL: Increases in stone prevalence, improvements in intracorporeal lithotripters, and refinements of crosssectional imaging that facilitate the operative approach. Provider-specific factors—training, surgeon age/experience, and practice setting may also contribute. Our group has
previously shown provider-specific attributes affect how upper tract calculi are treated, with decreasing use of URS among more senior urologists.4 In 2005, the American Board of Urology (ABU) mandated all urologists seeking certification to submit operative case logs from a continuous 6-month period in their practice. We performed a study using these data to better understand contemporary trends in the utilization of PCNL, urologistspecific access, as well as provider-specific factors and their overall relationship to PCNL utilization. Methods
After 1985, certification given by the ABU for urologists must be renewed every 10 years. After 2005, candidates applying to the ABU for initial certification or recertification must submit electronic surgical practice logs as one component of their application. This case log represents 6 consecutive months of surgical practice chosen from an 18-month
James Buchanan Brady Urological Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland.
1304
PCNL PRACTICE PATTERNS
1305
period preceding application submission. Diagnoses are recorded in the practice log according to the International Statistical Classification of Diseases and Related Health Problems (ICD-9). Surgical procedures are classified by Current Procedural Terminology (CPT) code numbers. Patient-specific data in these logs are minimal (age and sex). Provider-specific data are more readily available, including practice type, practice population, candidate fellowship training, and overall case volume. No individual case information or outcome data were available. We analyzed these self-reported 6-month case logs from urologists who certified or recertified between 2004 and 2013. This time interval allowed us to theoretically capture every certifying urologist in the United States. Surgeons with duplicate records were excluded. Surgeons who performed PCNL were identified by CPT coding: 50080 and 50081; percutaneous access was identified by CPT 50395. Urologistspecific data, including fellowship training, practice type, and practice population, were used to further stratify the cohort performing these procedures. Trends were examined over the study period. For the purposes of our analysis, high-volume practitioners were defined as those who performed > 10 PCNLs per submitted practice log. Results
A total of 7278 urologists submitted case logs to the ABU between 2004 and 2013. Table 1 summarizes demographic and provider-specific factors for the entire cohort. All three certification groups (initial, first, and second) were similarly represented. The median ages of the initial certification group, first recertification group, and second recertification group were 36.0, 43.7 and 53 years, respectively; 22% and 5% of the cohort had any fellowship training and endourology/ stone training, respectively. The majority of urologists submitting case logs (62%) were in a private practice setting; 38% of all urologists practiced in large, urban settings ( > 1,000,000 persons). Based on submitted case logs, 41% of all urologists did not perform any PCNL during their study period. Furthermore, 6% of certifying urologists were considered highvolume PCNL performers, defined as > 10 PCNL/case log.
Table 1. Demographics of Study Cohort Urologists submitting logs Initial certification 1st recertification 2nd recertification Median age Initial certification 1st recertification 2nd recertification Fellowship training Stones Nonstones Practice setting Private Academic Hybrid Did not perform PCNL > 10 PCNL
FIG. 1. Temporal trends in percutaneous nephrolithotomy (PCNL) and urologist-performed access. Figure 1 demonstrates the temporal trend of PCNL utilization as well as urologist-directed access. In 2004, a total of 1330 PCNL procedures were performed, and in 2013, that number had increased to 2888, a 117% increase over 10 years. Urologist-directed access concordantly increased over time, with 14.5% of PCNL cases utilizing urologist access in 2004 and 20.4% in 2012, a 29% increase. Certification status (initial, first, or second) did not correlate with urologist access. Figures 2 and 3 demonstrate the utilization of PCNL based on urologist age (certification status). Although use of PCNL has increased over time among all urologists, initially certifying urologists perform more PCNLs than older urologists; 53% of initially certifying practitioners performed any PCNL procedures compared with 29% among the most senior (second recertification) group. Along with this, initially certified urologists comprised the largest percentage of all high-volume PCNL performers. Figure 4 provides a similar analysis with regard to fellowship training status. Urologists fellowship trained in stones were much more likely to utilize PCNL (66%) and be high-volume PCNL surgeons (26%). Academic practices
7278 2373 (33) 2644 (36) 2261 (31) 44.1 yrs 36 43.7 53 1578 (22) 375 (5) 1193 (17) 4497 2223 558 2946 464
(62) (31 (7) (41) (6)
FIG. 2. Temporal trends in percutaneous nephrolithotomy (PCNL) utilization by certification cohort.
1306
FIG. 3. Utilization of percutaneous nephrolithotomy based on urologist certification cohort. contained a higher proportion of high-volume PCNL surgeons (10%) compared with urologists in private or hybrid practices (5%); 7% of urologists in heavily populated areas ( > 1,000,000) were high-volume surgeons, compared with 5.6% and 4.6% of surgeons in medium size and small practice settings, respectively. Discussion
PCNL is the standard treatment for patients with complex or large-volume upper urinary tract calculi. Although ureteroscopic technology has progressed, recent data suggest that the utilization of URS and SWL has declined for patients with large calculi, whereas that of PCNL is steadily increasing.5 Ghani and associates5 abstracted data from the Nationwide Inpatient Sample (NIS) from 1999 to 2009 and found the number of PCNLs performed annually increased by
FIG. 4. Utilization of percutaneous nephrolithotomy based on fellowship training (FT).
JAYRAM AND MATLAGA
47% during this period. These findings are consistent with that of Morris and colleagues,2 who used the same database from 1998 to 2002, where PCNL utilization more than doubled from 1.2 per 100,000 U.S. residents to 2.5, a greater than 100% increase over that period. This trend does not appear to be a global one, though, because recent analyses from Canada, Australia, and the United Kingdom suggest PCNL utilization in those regions has remained stable or even slightly declining while endoscopic interventions for stone disease continue to climb.3,6–8 Our study, using ABU selfreported case logs to determine the utilization of PCNL among certifying urologists, confirms significant increase in the use of PCNL and also analyzes provider-specific factors responsible for this phenomenon. We have previously used ABU log data to evaluate trends in the management of upper urinary tract calculi.4 In this article, we found that initially certifying urologists used URS in their management of upper tract stones significantly more than older urologists, who tended to use SWL. The current study focuses on PCNL-specific trends, and augments these findings—PCNL is much more frequently performed by younger urologists, and the gap is especially wide between initially certifying (youngest) and second recertification groups (oldest). Younger urologists have likely had greater access to stone disease given increasing prevalence of urolithiasis and better detection methods.9 Furthermore, significant progress in endoscopic techniques as well as advances in PCNL safety, efficacy, and intracorporeal lithotripters likely have allowed many younger urologists greater facility and comfort with the procedure. Certification status did not correlate with urologistdirected access. Based on CPT coding, urologists obtained their own access in approximately 21% of PCNLs performed in 2013. Lee and coworkers10 performed a survey study of urologists and demonstrated significantly more urologists who had residency training in obtaining access performed PCNL and continued to get their own access in practice. This is consistent with our findings regarding fellowship training in stones, because these practitioners were much more likely to perform PCNL and be high-volume PCNL surgeons. Practice setting also was found to be associated with PCNL use in our study. Providers in academic and heavily populated areas tended to perform PCNL and be high-volume PCNL surgeons more frequently than providers in rural and low population density areas. This finding was previously reported by Morris and associates2 from their NIS study, where they showed the majority of PCNLs were being performed at urban teaching hospitals, and PCNLs performed at low PCNL volume or low-discharge volume PCNL carried an increased likelihood of mortality. Although ABU case log data are independently reviewed and validated, the log itself is self-reported and may contain provider bias. For example, it is not known how reliably urologist-directed access is captured by CPT code 50395. The overall accuracy of the dataset, however, is supported by the relative consistency of data from year to year within the certifying cohorts. Furthermore, data regarding case outcomes based on provider-specific factors, a potentially insightful metric, were not available. The time span used for our study was designed to attempt to capture every practicing urologist in the United States, further adding to the credibility of the data.
PCNL PRACTICE PATTERNS Conclusions
Based on self-reported ABU case logs, the utilization of PCNL and urologist-directed access has increased significantly over the past decade. Younger and fellowship-trained urologists are the primary users of PCNL, and the majority of senior urologists do not perform this operation. High-volume PCNL surgeons appear to be concentrated in academic and heavily populated practice settings. Although the incidence of urolithiasis is increasing, provider-specific factors impact the utilization of PCNL. Our findings can serve to inform future discussions on the regionalization of specialized urologic care. Acknowledgment
This research publication was made possible by support from Mr. and Mrs. Jerry and Helen Stephens. Disclosure Statement
Dr. Matlaga is a consultant for Boston Scientific. No competing financial interests exist for Dr. Jayram. References
1. Ghani KR, Sammon JD, Bhojani N, et al. Trends in percutaneous nephrolithotomy use and outcomes in the United States. J Urol 2013;190:558–564. 2. Morris DS, Wei JT, Taub DA, et al. Temporal trends in the use of percutaneous nephrolithotomy. J Urol 2006;175: 1731–1736. 3. Ordon M, Urbach D, Mamdani M et al. The surgical management of kidney stone disease: A population-based time series analysis. J Urol 2014. Epub before print. 4. Matlaga BR; American Board of Urology. Contemporary surgical management of upper urinary tract calculi. J Urol 2009;181:2152–2156.
1307
5. Ghani KR, Sammon JK, Karakiewicz PI, et al. Trends in surgery for upper urinary tract calculi in the USA using the Nationwide Inpatient Sample: 1999–2009. BJU Int 2013; 112:224–230. 6. Lee MC, Bariol SV. Evolution of stone management in Australia. BJU Int 2011;108(suppl 2):29–33. 7. Armitage JN, Withington J, van der Meulen J, et al. Percutaneous nephrolithotomy in England: Practice and outcomes described in the Hospital Episode Statistics database. BJU Int 2014;113:777–782. 8. Armitage JN, Irving SO, Burgess NA; British Association of Urological Surgeons Section of Endourology. Percutaneous nephrolithotomy in the United Kingdom: Results of a prosecptive data registry. Eur Urol 2012;61:1188–1193. 9. Scales CD Jr, Smith AC, Hanley JM, et al. Prevalence of kidney stones in the United States. Eur Urol 2012;62: 160–165. 10. Lee CL, Anderson JK, Monga M. Residency training in percutaneous renal access: Does it affect urological practice? J Urol 2004;171:592–595.
Address correspondence to: Brian R. Matlaga, MD, MPH 600 North Wolfe Street Park 221 Baltimore, MD 21287 E-mail: [email protected]
Abbreviations Used ABU ¼ American Board of Urology PCNL ¼ percutaneous nephrolithotomy SWL ¼ shockwave lithotripsy URS ¼ ureteroscopy
