Regionalization of Renal Surgery: Impact of Hospital Volume on Utilization of Partial Nephrectomy

Marc C. Smaldone1, Jay Simhan1, Daniel Canter2, Russell Starkey3, Fang Zhu1, Karyn Stitzenberg4, Alexander Kutikov1, Robert G. Uzzo1

1Fox Chase Cancer Center, Philadelphia, PA, 2Emory University, Atlanta, GA, 3Thomas Jefferson University, Philadelphia, PA, 4University of North Carolina, Chapel Hill, NCAbstractIntroduction and Objectives: In an effort the reduce the risk of chronic kidney disease and its attendant cardiovascular and mortality risks, the AUA guidelines recommend nephron sparing surgery for all localized lesions amenable to partial nephrectomy. The purpose of this study was to investigate trends in regionalization of care for surgical management of renal cell carcinoma (RCC).  Methods: Using 1996 to 2009 hospital discharge data from NY, NJ, and PA, patients undergoing surgery for RCC were identified using ICD-9 coding. We assigned hospital volume status by quintiles based on relative proportions of renal procedures (radical nephrectomy, partial nephrectomy, ablation) performed on a per hospital basis in 1996; very low volume hospital: 0-6 (VLVH), low: 7-12 (LVH), moderate: 13-20 (MVH), high: 21-46 (HVH) and very high volume hospital: ≥47 (VHVH). Procedure performance by hospital volume status was assessed over time using regression models and patient characteristics were compared between groups.  Results:  Of 58,157 patients identified, there was a significant shift towards regionalization for total renal procedures to VHVH’s (18 to 48%, p<0.001) from 1996 to 2009. Patients treated at a VHVH were less likely to be older (ages 65-74 (OR 0.89 [CI 0.82-0.96]); 75-84 (OR 0.89 [CI 0.84-0.96]), have Medicaid (OR 0.68 [0.50-0.91]), Medicare (OR 0.88 [0.82-0.94]), or be uninsured (OR 0.39 [CI 0.30-0.51]). Over the duration of the study period, partial nephrectomy treatment increased from 8.3% (1996) to 35.4% (2009). Adjusting for confounders, use of radical nephrectomy significantly decreased across volume strata compared to VLVH (all p values <0.001), while trends in use of ablation were less affected by volume status. A significant trend towards increased utilization of partial nephrectomy was observed with increasing volume status; LVH (OR 1.3 [CI 1.1-1.6]), MVH (OR 1.7 [CI 1.5-1.9]), HVH (OR 2.2 [CI 1.9-2.5]), VHVH (OR 4.3 [CI 4.0-4.6]).  Conclusions: While increasing overall, performance of partial nephrectomy has shifted to higher volume hospitals from 1996 to 2009. Inequities in access to care exist and must be addressed in future studies.

Data Analysis• Group characteristics stratified by procedure and volume were

compared using chi square analyses.• Proportion of procedures performed by volume status were

compared between 1996 and 2009.• Multivariate logistic regression models:

• provided estimates of the odds of undergoing any renal procedure or individual procedures (nephrectomy, partial nephrectomy, ablation) in each volume category controlling for demographics, year treated, and total number of procedures.

• tested associations between patient characteristics and volume category controlling for year treated and total number of procedures performed

Methods• We used hospital discharge data (1996-2009) from NY, NJ, and PA provided by

Databay resources•From 1996-1999, only NY and PA data were available

• Using ICD-9 coding, all patients ≥18 years undergoing renal procedures (nephrectomy, partial nephrectomy, ablation) for renal cell carcinoma (RCC) were identified

• Hospitals were ranked by number of renal procedures performed in 1996• Using 1996 rankings, five equally proportioned volume groups were determined

by total annual renal procedures performed (quintiles)•Very low (VLVH): 0-6; Low (LVH): 7-12; Medium (MVH): 13-20; High (HVH): 21-46; Very high (VHVH): ≥47

• Cut points were applied to each subsequent year to determine regionalization trends by volume category

ResultsFigure 1. Number of renal procedures/hospital by year

Introduction• The AUA Guidelines recommend that nephron sparing surgery should be

considered in all appropriate surgical candidates with a clinical T1 renal mass presuming that adequate oncologic control can be achieved1.

• Performance of nephron sparing surgery has been proposed as a candidate quality of care indicator2.

• Hospital and surgeon volume has been associated with improved morbidity & mortality outcomes following cancer surgery3-4.

• Centralization over time to high volume hospitals has been demonstrated in non-genitourinary malignancies but have been poorly characterized for urologic cancers5-6.

• Use of hospital claims data affords the opportunity to assess regionalization trends in procedure performance over time.

Characteristic TotalN = 58,157

RNN = 42,516

PNN = 13,239

ABLN = 2,402

P Value

  N (%)  Age (years)   <0.0001 <55 15,775 (27.3) 11,099 (26.1) 4,307 (32.5) 466 (19.4)  

≥55 to <65 14,936 (25.8) 10,701 (25.2) 3,740 (28.3) 555 (23.1)  

≥65 to <75 15,719 (27.2) 11,587 (27.3) 3,528 (26.7) 668 (27.9)  

≥75 to <85 10,193 (17.6) 8,071 (19.0) 1,563 (11.8) 602 (25.1)  

≥85 1263 (2.2) 1,058 (2.5) 101 (0.8) 110 (4.6)  Race   <0.0001 Caucasian 45,665 (78.9) 33,687 (79.2) 10,324 (78.0) 1,868 (78.8)  

African American

5,285 (9.1) 3,843 (9.0) 1,208 (9.1) 254 (10.6)  

Other 6,691 (11.6) 4,877 (11.5) 1,581 (11.9) 270 (11.2)   Unknown 245 (0.4) 109 (0.3) 126 (1.0) 10 (0.4)  Gender   <0.0001 Female 22,256 (38.5) 16,671 (39.2) 4,750 (35.9) 950 (39.6)  

Male 35,630 (61.6) 25,845 (60.8) 8,489 (64.1) 1,452 (60.5)  

Payer Group   <0.0001 Private 27,749 (47.9) 19,605 (46.1) 7,325 (55.3) 945 (39.3)  

Medicare 25,310 (43.7) 19,369 (45.6) 4,753 (35.9) 1,299 (54.1)  

Medicaid 3,280 (5.7) 2,338 (5.5) 851 (6.4) 109 (4.5)   Uninsured 887 (1.5) 694 (1.6) 178 (1.3) 22 (0.9)   Unknown 660 (1.1) 510 (1.2) 132 (1) 27 (1.1)  RN – radical nephrectomy, PN – partial nephrectomy, ABL - ablation

Table I. Characteristics of Patients Undergoing Renal Surgery from 1995-2009 By Procedure Type

0%

10%

20%

30%

40%

50%

60%

1996 2009

Year

% A

ll P

roce

du

res 0-6

7-12

13-20

21-46

47+

** *

*

*

* p<0.0001 1996 2009

Figure 2. Proportion of Renal Procedures By Volume Strata (1996 & 2009)

Characteristic VLVHN = 7,187

LVHN = 8,885

MVHN = 8,554

HVHN = 14,007

VHVH N = 19,524

P Value

  N (%)  Age (years)   <0.0001 <55 1,823 (25.4) 2,212 (24.9) 2,223 (26.0) 3,877 (27.7) 5,737 (29.4)  

≥55 to <65 1,717 (23.9) 2,137 (24.1) 2,151 (25.2) 3,675 (26.2) 5,316 (27.2)  

≥65 to <75 1,946 (27.1) 2,570 (28.9) 2,398 (28.0) 3,699 (26.4) 5,171 (26.5)  

≥75 to <85 1,519 (21.1) 1,729 (19.5) 1,603 (18.7) 2,430 (17.4) 2,955 (15.1)  

≥85 182 (2.5) 237 (2.7) 179 (2.1) 326 (2.3) 345 (1.8)  Race   <0.0001 Caucasian 5,656 (78.7) 7,186 (80.9) 6,577 (76.9) 10,677 (76.2) 15,783 (80.8)  

African American

765 (10.6) 878 (9.9) 965 (11.3) 1,213 (8.7) 1,484 (7.6)  

Other 763 (10.6) 808 (9.1) 894 (14.5) 2,011 (14.4) 2,252 (11.5)   Unknown 3 (0.04) 13 (0.2) 118 (1.4) 106 (0.8) 5 (0.03)  Gender   <0.0001 Female 2,939 (40.9) 3,556 (40.0) 3,384 (39.6) 5,349 (38.2) 7,143 (36.6)  

Male 4,248 (59.1) 5,329 (60.0) 5,170 (60.4) 8.658 (61.8) 12,381 (63.4)  

Payer Group   <0.0001 Private 2,919 (40.6) 3,959 (44.6) 3,907 (45.7) 6,763 (48.3) 10,327 (52.9)  

Medicare 3,378 (47) 4,157 (46.8) 3,859 (45.1) 6,130 (43.8) 7,897 (40.5)   Medicaid 553 (7.7) 455 (5.1) 534 (6.2) 773 (5.5) 983 (5.0)   Uninsured 212 (3.0) 170 (1.9) 158 (1.9) 169 (1.2) 185 (1.0)   Unknown 125 (1.7) 144 (1.6) 96 (1.1) 172 (1.2) 132 (0.7)  VLVH – very low volume hospital, LVH – low volume hospital, MVH – medium volume hospital, HVH – high volume hospital, VHVH – very high volume hospital

Table II. Characteristics of Patients undergoing Renal Surgery from 1995-2009 by Volume Category

Very Low Volume Hospital Very High Volume HospitalCovariate OR [CI] Covariate OR [CI]Year Treated 0.89 [0.88-0.91] Year Treated 1.15 [1.1-1.2]Age (years)   Age (years)   ≥65 to <75 1.06 [1.04-1.08] ≥65 to <75 0.89 [0.82-0.96] ≥75 to <85 1.32 [1.2-1.5] ≥75 to <85 0.89 [0.84-0.96]Race   Gender   African American 1.36 [1.1-1.8] Male 1.07 [1.03-1.11] Gender   Payer Group   Male 0.94 [0.92-0.96] Medicaid 0.68 [0.5-0.9]Payer Group   Medicare 0.88 [0.8-0.9] Medicaid 1.81 [1.3-2.5] Uninsured 0.39 [0.3-0.5] Medicare 1.15 [1.1-1.2]     Uninsured 2.82 [1.7-4.6]    OR – odds ratio, CI – confidence intervalControlling for year treated, total number of procedures, age, race, gender, payer group

Table III. Patient Characteristics Associated with Treatment at Very Low Volume and Very High Volume Hospitals

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0-6 7-12 13-20 21-46 47+ 0-6 7-12 13-20 21-46 47+

1996 2009

Radical Nephrectomy partial nephrectomy Ablation

Figure 3. Renal Procedures By Type Stratified By Hospital Volume (1996-2009)

Hospital Volume Radical Nephrectomy Partial Nephrectomy Ablation

  Odds Ratio [Confidence Interval]

VLVH (reference)  

LVH 0.77 [0.7-0.9] 1.34 (1.1-1.6] 1.12 [1.10-1.14]

MVH 0.60 [0.5-0.7] 1.72 [1.5-1.9]  

HVH 0.48 [0.4-0.6] 2.15 [1.9-2.5] 1.53 [1.2-1.9]

VHVH 0.26 [0.2-0.3] 4.30 [4.0-4.6]  

VLVH – very low volume hospital, LVH – low volume hospital, MVH – medium volume hospital, HVH – high volume hospital, VHVH – very high volume hospital

Controlling for year treated, total number of procedures, age, race, gender, payer group

Table IV. Association Between Hospital Volume Category and Year Treated By Procedure Type

Limitations• Lack of patient specific co-morbidity, pathologic, &

complications data.• Our sample may not be generalizable to larger

populations due to geographic influences.• Definition of hospital volume status does not

specifically account for change in annual number of procedures performed.

Conclusions• These data demonstrate that there has been

extensive regionalization of renal procedures to VHVH’s from 1996-2009.

• While the proportion of partial nephrectomies performed has increased across all volume strata over time, utilization of partial nephrectomy has increased most dramatically at very high volume centers.

• Disparities in access to higher volume hospitals were evident in our cohort which should be the focus of further investigation.

References1.Campbell SC, Novick AC, Belldegrun A, et al: Guideline

for management of the clinical T1 renal mass. J Urol 182:1271-9, 2009

2.Hollenbeck BK, Taub DA, Miller DC, et al: National utilization trends of partial nephrectomy for renal cell carcinoma: a case of underutilization? Urology 67:254-9, 2006

3.Birkmeyer JD, Siewers AE, Finlayson EV, et al. Hospital volume and surgical mortality in the United States. NEJM (2002); 346: 1128-1137.

4.Hollenbeck BK, Dunn RL, Miller DC, et al. Volume based referral for cancer surgery: Informing the debate. J Clin Oncol (2007); 25 (1): 91-96.

5.Stitzenberg KB, Sigurdson ER, Egleston BL, et al. Centralization of cancer surgery: implications for patient access to optimal care. J Clin Oncol (2009); 27 (28): 4671-8.

6.Stitzenberg KB, Wong YN, Nielsen ME, et al. Trends in radical prostatectomy: centralization, robotics, and access to urologic cancer care. Cancer (2011); epub ahead of print.

Funded by Fox Chase Cancer Center via institutional support of the Kidney Cancer Keystone Program

Abstract #425