Journal of Gastrointestinal Surgery

, Volume 11, Issue 10, pp 1242–1252

Trends and Disparities in Regionalization of Pancreatic Resection

Authors

    • Department of SurgeryUniversity of Texas Medical Branch
  • Karl A. Eschbach
    • Department of Internal MedicineThe University of Texas Medical Branch
  • Courtney M. TownsendJr.
    • Department of SurgeryUniversity of Texas Medical Branch
  • William H. Nealon
    • Department of SurgeryUniversity of Texas Medical Branch
  • Jean L. Freeman
    • Department of Internal MedicineThe University of Texas Medical Branch
  • James S. Goodwin
    • Department of Internal MedicineThe University of Texas Medical Branch
Article

DOI: 10.1007/s11605-007-0245-5

Cite this article as:
Riall, T.S., Eschbach, K.A., Townsend, C.M. et al. J Gastrointest Surg (2007) 11: 1242. doi:10.1007/s11605-007-0245-5
  • 171 Views

Abstract

Background

The current recommendation is that pancreatic resections be performed at hospitals doing >10 pancreatic resections annually.

Objective

To evaluate the extent of regionalization of pancreatic resection and the factors predicting resection at high-volume centers (>10 cases/year) in Texas.

Methods

Using the Texas Hospital Inpatient Discharge Public Use Data File, we evaluated trends in the percentage of patients undergoing pancreatic resection at high-volume centers (>10 cases/year) from 1999 to 2004 and determined the factors that independently predicted resection at high-volume centers.

Results

A total of 3,189 pancreatic resections were performed in the state of Texas. The unadjusted in-hospital mortality was higher at low-volume centers (7.4%) compared to high-volume centers (3.0%). Patients resected at high-volume centers increased from 54.5% in 1999 to 63.3% in 2004 (P = 0.0004). This was the result of a decrease in resections performed at centers doing less than five resections/year (35.5% to 26.0%). In a multivariate analysis, patients who were >75 (OR = 0.51), female (OR = 0.86), Hispanic (OR = 0.58), having emergent surgery (OR = 0.39), diagnosed with periampullary cancer (OR = 0.68), and living >75 mi from a high-volume center (OR = 0.93 per 10-mi increase in distance, P < 0.05 for all OR) were less likely to be resected at high-volume centers. The odds of being resected at a high-volume center increased 6% per year.

Conclusions

Whereas regionalization of pancreatic resection at high-volume centers in the state of Texas has improved slightly over time, 37% of patients continue to undergo pancreatic resection at low-volume centers, with more than 25% occurring at centers doing less than five per year. There are obvious demographic disparities in the regionalization of care, but additional unmeasured barriers need to be identified.

Keywords

Pancreatic resectionVolume–outcome relationshipRegionalization of care

Introduction

As for many complex surgical procedures, a strong volume–outcome relationship has been demonstrated in patients undergoing pancreatic resection. Whereas the definition of “high-volume” has varied, multiple studies have shown that surgical mortality, length of stay, hospital charges/costs, and long-term mortality are all decreased when such procedures are performed at high-volume centers111 or by high-volume surgeons.2,12,13

Because of the strongly observed volume–outcome relationship, pancreatic resection is often evaluated despite it being a relatively uncommon surgical procedure. As pointed out by Birkmeyer,14 the heavy scrutinization of pancreatic resection is also partly attributable to the high baseline risks associated with the procedure and its usefulness as a prototype for other complex surgical procedures.

As health care reform becomes an increasingly important issue, regionalization of care to high-volume centers specializing in specific complex procedures will be a topic of debate. Regionalization is defined as the delivery of care at a limited number of selected provider sites. Based on the volume-outcomes data for pancreatic resection,110 regionalization has been recommended for this procedure. The Leapfrog group, which is a coalition of greater than 150 large public and private health care purchasers, is making efforts to concentrate selected surgical procedures in centers that have the best results.15 In January 2004, pancreatic resection was added to Leapfrog group’s list of procedures targeted for evidence-based referral. For pancreatic resection, the Leapfrog group’s standard for evidence-based referral is strictly based on the process measure of annual volume of procedures performed. They recommend a minimum volume of greater than 10 cases per year.

In the studies evaluating the volume–outcome relationship for pancreatic resection, the percentage of patients resected at low-volume centers ranges from 24% to 77%.14,6 As the data supports regionalization and a large percentage of patients are still being resected at low-volume centers, we sought to evaluate trends and disparities in regionalization of pancreatic resection subsequent to the introduction of the concept in the mid-1990s.

This study uses the Texas Hospital Inpatient Discharge database to evaluate temporal trends in the percentage of patients undergoing pancreatic resection at high-volume hospitals throughout the state over the time period 1999 through 2004. Texas was chosen as it serves as a good model for regionalization throughout the United States. Texas has the largest rural population in the United States,16 the highest percentage of people without health insurance,17 and no ethnic majority. One-fifth of the state’s population lives in counties where the whole county has been designated by the U.S. Health Resources and Services Administration as medically underserved.18 As a result, patients often travel large distances to medical centers. We confirmed the volume–outcome relationship for pancreatic resection in Texas by comparing the in-hospital mortality, perioperative lengths of stay, and total charges between low and high-volume hospitals. In addition, we evaluated geographic patterns of referral and regionalization to high-volume centers and performed a multivariate analysis to determine the factors that predict resection at high-volume centers.

Methods

Data Source

Data from the Texas Hospital Inpatient Discharge Public Use Data File (PUDF) for the years 1999 through 2004 are used for this study. The data are collected by the Texas Department of State Health Services, Texas State Health Care Information Center (THCIC), Center for Health Statistics to develop administrative reports on the use and quality of hospital care in Texas.19 The database includes all discharge records for 466 participating non-federal hospitals in Texas. It has 205 data fields in a base data file and 13 data fields in a detailed charges file. The data include patient demographics, hospital information, lengths of stay, ICD-9 diagnosis codes, ICD-9 procedure codes, hospital day of procedure, hospital charges, payer information, and discharge status.

Study Population/Patient Characteristics

For the years 1999 through 2004, all discharges with a primary procedure code for pancreatic resection (ICD-9 procedure codes, 52.6, 52.7, 52.51, 52.52, 52.53, and 52.59; see Table 1) were selected. ICD-9 procedure codes 52.6, 52.7, 52.51, 52.53, and 52.59 were considered pancreatic head resections. ICD-9 procedure code 52.52 was considered distal pancreatic resection and 52.59 was considered pancreatectomy, not otherwise specified. Pancreatic resection for any reason including periampullary adenocarcinoma, chronic pancreatitis, and other benign and malignant diseases of the pancreas were included. Patients were classified as having periampullary adenocarcinoma (ICD-9 diagnosis codes 152.0–157.9, see Table 1) or having other pancreatic diseases (all other ICD-9 diagnosis codes).
Table 1

ICD-9 Procedure and Diagnosis Codes

Code

Definition

ICD-9 Procedure code

52.6

Pancreatectomy (total) with synchronous duodenectomy

52.7

Pancreaticoduodenectomy, radical (one-stage; two-stage)

52.51

Proximal pancreatectomy (head; with part of body; with synchronous duodenectomy)

52.52

Distal pancreatectomy (tail; with part of body)

52.53

Radical / subtotal pancreatectomy

52.59

Pancreatectomy / Pancreaticoduodenectomy partial NEC

ICD-9 Diagnosis code

152.0

Malignant neoplasm of the duodenum

156.0

Malignant neoplasm of gallbladder

156.1

Malignant neoplasm of extrahepatic bile ducts

156.2

Malignant neoplasm of ampulla of Vater

156.8

Malignant neoplasm other specified sites of gallbladder and extrahepatic bile ducts

157.0

Malignant neoplasm of head of pancreas

157.1

Malignant neoplasm of body of pancreas

157.2

Malignant neoplasm of tail of pancreas

157.3

Malignant neoplasm of pancreatic duct

157.8

Malignant neoplasm of other specified sites of pancreas

157.9

Malignant neoplasm of pancreas, part unspecified

To evaluate trends in regionalization in Texas, patients living out of state (or country) were excluded from the analysis. In addition, patients less than 18 years of age were excluded from the analysis. Age was defined as age groups based on the available data: 18–44 years, 45–54 years, 55–64 years, 65–74 years, and >75 years. These inclusion and exclusion criteria provided a cohort of 3,189 patients who underwent pancreatic resection in Texas between 1999 and 2004, inclusive.

For all patients with zip code data available (n = 3,161), we calculated the following distances: 1) the distance to the hospital at which the surgery was performed, 2) the distance to the nearest high-volume hospital, and 3) the distance to the nearest low-volume hospital.

Independent variables examined in the analysis included patient age group, gender, race/ethnicity (Hispanic, non-Hispanic white, non-Hispanic black, and other), diagnosis (periampullary cancer or other), procedure (distal pancreatectomy, pancreatic head resection, vs. other), year of diagnosis, admission type (emergent or elective), insurance status (uninsured, Medicare/Medicaid, other insurance), and distance to nearest high-volume facility. To control for patients’ comorbidities we used a variable included in the discharge data public use file called “Severity of Illness.” This variable is based on the all-patient refined diagnosis-related grouper (DRG) and considers comorbidity, age, and certain procedures to calculate the “severity of illness” (on a 0–4 scale), with 4 being the most severe. As only two patients had illness severity scores of 0, these were combined with the scores of 1 for the purpose of the analysis.

Hospital Volume/Hospital Characteristics

A Texas hospital was included in the analysis if at least one pancreatic resection was performed there in the 6-year time period. Pancreatic resections performed on patients from out of the state or country were included when determining a hospital’s volume status. Hospitals were then classified into high-volume and low-volume providers based on the 2004 Leapfrog criteria,14 greater than 10 cases per year.

The number of pancreatic resections performed by each hospital each year was examined. The criteria to qualify as a high-volume provider were a minimum volume of more than 10 pancreatic resections per year for 3 of the 6 years of the study and an average volume during the 6-year period of >10 pancreatic resections. Only two hospitals did greater than 10 cases per year for 3 years, but did not meet the average volume requirements to be considered high-volume hospitals. Hospital volume was determined before removing non-Texas residents.

To provide more detail for some analyses on the distribution of pancreatic resections throughout the state, the volume criteria were further subdivided into hospitals that performed less than five resections per year, 5–10 resections per year, 11–19 resections per year, and >20 resections per year. Besides resection at a high-volume center, other outcome variables of interest included in-hospital mortality, the lengths of hospital stay (total and postoperative), and the total hospital charges. Given the nature of the dataset, 30-day mortality could not be determined.

Statistical Analysis

SAS Statistical Software, version 9.1.3 (Cary, NC) was used for all statistical analyses. The percentage of patients undergoing surgical resection at high-volume hospitals each year was calculated. Trends were evaluated for statistical significance using the Cochran-Armitage test for trend.

The patient characteristics, hospital characteristics, and outcome variables were compared between high- and low-volume providers. The primary outcome variable of interest was resection at a high-volume center. Bivariate analyses were used to determine which independent variables were associated with resection at a high-volume center. Significance was accepted at the p < 0.05 level. All means are expressed as mean + standard deviation and all proportions are expressed as percentages. Chi-square analysis was used to compare proportions for all categorical data and t tests were used to compare all continuous variables between the high- and low-volume providers.

A logistic regression model was used to estimate the odds ratio for receipt of surgical resection at a high-volume center. Year and distance to the nearest high-volume center were modeled as a continuous variable. Patient age group, gender, race, diagnosis, illness severity, admission status, insurance status, type of resection, and distance to a high-volume center were used as covariates to determine the independent predictors of surgical resection at a high-volume center. Categorical variables were modeled as a series of binary variables referenced to a single group specified for each variable.

Results

From January 1999 through December 2004, 3,189 pancreatic resections were performed on Texas residents at 157 hospitals throughout Texas. The number of resections per year increased from 409 resections in 1999 to 624 resections in 2004 (Fig. 1). A total of 1,254 (87.8%) resections were performed at hospitals that were members of the Council of Teaching Hospitals.
https://static-content.springer.com/image/art%3A10.1007%2Fs11605-007-0245-5/MediaObjects/11605_2007_245_Fig1_HTML.gif
Figure 1

The number of pancreatic resections per year of the study in Texas, 1999–2004.

Overall Cohort

The patient demographic factors, procedure type, diagnosis, illness severity, and mortality risk are summarized in Table 2. Patients aged 55–64 accounted for 24.9% of patients undergoing pancreatic resection and patients aged 65–74 accounted for 24.4%. The gender distribution was nearly equal, with 1,476 male patients (48.4%). The majority of patients (62.9%) were non-Hispanic White. Hispanic patients comprised 18.9% of the cohort and non-Hispanic Black patients accounted for 11.2% of the cohort. Some 228 (7.2%) patients undergoing pancreatic resection were uninsured. Of the insured patients, 1,366 (42.9%) were insured by Medicare/Medicaid and 1,589 (49.9%) had other types of insurance including private insurance and health maintenance organization (HMO) coverage. Based on the APR-DRG Grouper, version 20, patients were assigned “severity of illness” scores on a 1–4 scale. The distribution of “severity of illness” scores is detailed in Table 2.
Table 2

Overall Cohort (n = 3,189)

 

N

Percent (%)

Age group

 18–44 years

526

17.6

 45–54 years

570

17.9

 55–64 years

793

24.9

 65–74 years

780

24.4

 >74 years

484

15.2

Gender

 Male

1,476

48.4

 Female

1,572

51.6

Race/Ethnicity

 Non-Hispanic White

2,006

62.9

 Non-Hispanic Black

356

11.2

 Hispanic

602

18.9

 Other

225

7.0

Insurance type

 Medicare/Medicaid

1,366

42.9

 Other insurance

1,589

49.9

 Uninsured

228

7.2

Severity of illness

 Score = 1

159

5.0

 Score = 2

553

17.3

 Score = 3

1,367

42.9

 Score = 4

1,110

34.8

Diagnosis

 Periampullary adenocarcinoma

1,841

57.7

 Chronic pancreatitis

435

13.6

 Other malignant disease

450

14.1

 Other benign disease

463

14.5

Admission type

 Elective

1,911

71.6

 Emergent

757

28.4

Type of operation

 Pancreaticoduodenectomy

2,189

68.6

 Distal pancreatectomy

780

24.5

 Pancreatectomy not otherwise specified

220

6.9

The most common reason for pancreatic resection was periampullary adenocarcinoma, in 57.8% of patients, followed by chronic pancreatitis in 13.6%, other benign disease processes in 14.5%, and other malignant disease processes in 14.1%. 71.6% of resections were performed electively. Distal pancreatectomy was performed in 24.5% of patients (ICD-9 Procedure Code 52.52), whereas pancreaticoduodenectomy was performed in the remaining 75.5% (ICD-9 Procedure Codes 52.51, 52.53, 52.59, 52.6, 52.7; see Tables 1 and 2).

Trends in Resection at High-Volume Centers

Of the 3,189 pancreatic resections, 1,849 (58.0%) were performed at the 14 high-volume centers in Texas, as defined by the leapfrog criteria of greater than 10 resections per year, and 1,340 (42.0%) were performed at 143 hospitals performing <10 pancreatic resections per year. As shown in Fig. 2, 994 cases were (31.2%) performed at centers doing fewer than five resections per year, 346 (10.9%) were performed at centers doing 5–10 resections per year, 818 (25.6%) were performed at centers doing 11–19 resections per year, and 1,031 (32.3%) were performed at centers doing 20 or more resections per year.
https://static-content.springer.com/image/art%3A10.1007%2Fs11605-007-0245-5/MediaObjects/11605_2007_245_Fig2_HTML.gif
Figure 2

The percentage of pancreatic resections performed at centers in Texas performing <5, 5–10, 11–19, and >20 pancreatic resections per year.

From 1999 to 2004, the percentage of patients resected at high-volume centers increased from 54.5% to 63.3% (Fig. 3, P = 0.0004 for trend). Much of this increase was accounted for by decreased volume at the centers performing fewer than five pancreatic resections per year (very-low-volume centers). In 1999, 35.5% of resections in Texas were performed at centers doing fewer than five resections per year, whereas in 2004 only 26.0% were done in very-low-volume centers.
https://static-content.springer.com/image/art%3A10.1007%2Fs11605-007-0245-5/MediaObjects/11605_2007_245_Fig3_HTML.gif
Figure 3

Trends in the percentage of patients undergoing resection at high-volume centers, shown by the dotted line with diamonds, and low-volume centers, shown by the solid line with squares.

Comparison of High- and Low-Volume Centers

As shown in previous studies evaluating volume–outcome relationships after pancreaticoduodenectomy,110 high-volume centers had lower unadjusted mortality rates (3.3% vs. 7.4%, P < 0.0001), shorter lengths of hospital stay (median 12 vs. 14 days, P = 0.0004), and lower total hospital charges (median $55,000 vs. $67,000, P = 0.008, Table 3). Over the study period, the overall crude mortality rates after pancreatic resection decreased from 6.6% in 1999 to 3.9% in 2004 (P = 0.01). The mortality at low-volume hospitals did not change, whereas the mortality at high-volume hospitals decreased over the same time period from 6.7% to 2.3% (P = 0.003).
Table 3

Bivariate Comparison of Low- and High-Volume Centersa

 

Low Volume %

High Volume %

P value

Unadjusted in-hospital mortality

7.4%

3.3%

<0.0001

Total length of stay (median)

14 days

12 days

0.0004

Total hospital charges

$67,000

$55,000

0.008

Age group

 18–44 years

16.9%

18.2%

0.006

 45–54 years

16.4%

18.9%

 

 55–64 years

24.4%

25.2%

 

 65–74 years

24.5%

24.5%

 

 >74 years

17.8%

13.2%

 

Percent male

45.8%

50.3%

0.02

Race/Ethnicity

 Non-Hispanic white

57.6%

66.8%

<0.0001

 Non-Hispanic black

10.4%

11.7%

 

 Hispanic

26.6%

13.3%

 

 Other

5.4%

8.2%

 

Insurance type

 Medicare/Medicaid

45.4%

41.1%

0.0024

 Other insurance

46.5%

52.4%

 

 Uninsured

8.1%

6.5%

 

Severity of illness

 Score = 1

6.3%

4.1%

0.0012

 Score = 2

17.5%

17.2%

 

 Score = 3

39.6%

45.3%

 

 Score = 4

36.6%

34.4%

 

Diagnosis

 Periampullary adenocarcinoma

59.8%

56.2%

0.039

 Other

40.2%

43.8%

 

Elective admission

60.6%

79.5%

<0.0001

Type of operation

 Pancreaticoduodenectomy

64.1%

71.9%

<0.0001

 Distal pancreatectomy

28.8%

21.3%

 

 Pancreatectomy not otherwise specified

7.1%

6.8%

 

aHigh-volume defined as >10 cases/year

Patients undergoing resection at high-volume centers were more likely to be male (50.3 vs. 45.9%, P = 0.02), non-Hispanic white (66.7% vs. 57.6%, P < 0.0001), have non-federal insurance (52.4% vs. 46.5%, P < 0.0001), undergo pancreatic head resection (71.2% vs. 64.1%, P < 0.0001), and to be undergoing elective procedures (79.5% vs. 60.6%, P < 0.0001, Table 3). They were less likely to have periampullary cancer (56.2% vs. 59.9%, P = 0.039). Patients resected at high-volume hospitals had higher “severity of illness” scores (P = 0.0012).

Distance to High-Volume Hospital and Hospital of Surgical Procedure

Data on the distance from a patient’s home zip code to: 1) the hospital performing their surgery and 2) the nearest high-volume hospital were available on 3,161 of the 3,189 patients. Of the patients, 24.9% lived within 10 mi from a high-volume provider; 50.1% lived within 25 mi of a high-volume provider; 61.5% lived within 50 mi of a high-volume provider; and 73.7% lived within 75 mi of a high-volume provider. For the overall cohort, patients traveled a mean distance of 41.9 + 70.7 mi (median = 14.1 mi, range 0.3–678 mi) to the hospital where their surgery was performed. The mean distance to the nearest high-volume provider was 67.3 + 94.9 mi (median = 26.0 mi) and to the nearest low-volume provider was 9.9 + 13.1 mi (median = 4.5 mi). Of the patients resected at low-volume centers, 19% traveled a distance further than the distance to the nearest high-volume center to have their surgery performed. Figure 4 divides the patient population into 20 equal-size groups based on progressive distance from the nearest high-volume hospital, then graphs the percentage of patients undergoing resection at a high-volume center for each group.
https://static-content.springer.com/image/art%3A10.1007%2Fs11605-007-0245-5/MediaObjects/11605_2007_245_Fig4_HTML.gif
Figure 4

Patients were divided into 20 equal-sized groups based on distance to the nearest high-volume provider. This graph shows the percentage of patients using a high-volume provider (x-axis) based on their distance in miles from the nearest high-volume provider (y-axis). There is a dip and then rise in the use of high-volume providers based on distance.

To further explore factors affecting utilization of high-volume hospitals, we stratified patients by whether they lived within 75 mi of a high-volume hospital. When evaluating the 73.7% of patients who lived within 75 mi (n = 2,329) of a high-volume hospital, 34% (n = 792) were resected by at a low-volume hospital and 66% (n = 1,537) were resected at a high-volume center. Patients resected at a high-volume center traveled further than patients resected at low-volume centers (mean 32.9 vs. 13.1 mi, median 17.8 vs. 7.4 mi, P < 0.0001). In addition, patients resected at high-volume centers often traveled to a high-volume center that was not the closest to their home, with a mean distance of 32.9 + 42.6 mi to the hospital performing the surgery and mean distance of 22.7 + 20.3 mi to the nearest high-volume hospital.

Of the 832 patients who lived more than 75 mi from a high-volume center, they traveled a mean distance of 86.1 + 111.2 mi (median = 37.3 mi) to get to the hospital performing their surgery. The mean distance to a high-volume hospital was 191.7 + 109.8 mi (median = 145.6 mi). Only 36% were resected at high-volume hospitals. Those resected at low-volume hospitals traveled 27.8 + 54.8 mi (median = 8.6 mi) to have their surgery, whereas those resected at high-volume hospitals traveled 188.4 + 111.2 mi (median = 150.6). On average, patients resected at high-volume centers lived closer to the nearest high-volume center that those resected at low-volume centers (149.2 mi vs. 215.9 mi, P < 0.0001).

Figure 5 is a thematic map of Texas showing the location of the 14 high-volume hospitals and the percentage of resections that are at high-volume hospitals by hospital service area. We noticed several patterns in the distance data (refer to map in Fig. 5). The 14 high-volume providers are located in six of Texas’s 254 counties: Dallas, Tarrant, Bell, Harris, Bexar, and Galveston. These counties encompass the major cities of Dallas (Dallas County), Fort-Worth (Tarrant County), Temple (Bell County), Houston (Harris County), San Antonio (Bexar County), and Galveston (Galveston County). Patients in these counties are more likely to go to a high-volume provider (66.2%) than those in other counties (52.1%, P < 0.0001). However, within these counties, high-volume centers have varying levels of monopoly. Of patients living in Galveston county, 96.7% were resected at high-volume centers, followed by 77.4% in Bell county, 71.0% in Dallas county, 66.3% in Harris County, 57.4% in Bexar County, and 13.6% in Tarrant county (P < 0.0001).
https://static-content.springer.com/image/art%3A10.1007%2Fs11605-007-0245-5/MediaObjects/11605_2007_245_Fig5_HTML.gif
Figure 5

A thematic map of Texas showing the location of the 14 high-volume hospitals and the percentage of resections that are at high-volume hospitals by hospital service area. An H on the map denotes each high-volume provider. Dallas, Tarrant, Bell, Harris, Bexar, and Galveston counties, the six counties containing the 14 high-volume centers are labeled.

Multivariate Logistic Regression Analysis

We fit a logistic regression model to predict resection at a high-volume center. An odds ratio (OR) of greater than 1 implies increased likelihood of being resected at a high-volume center. The final model is shown in Table 4. As a patient’s age group increased, the likelihood of being resected at a high-volume center decreased. Likewise, Hispanic patients, patients with periampullary cancer, patients undergoing emergent procedures, and patient’s undergoing distal pancreatic resections (compared to head of pancreas resections) were less likely to be resected at high-volume centers. The distance to the nearest high-volume center was a significant predictor of resection at a high-volume center. Compared to patients living within 10 mi of a high-volume center, the odds of resection at a high-volume center decreased by 7% with each 10-mi increase in distance. In the final model, the year of surgery was an independent predictor of resection at a high-volume center, with a 6% increase in likelihood per advancing year. Patients with increased illness severity were more likely to be resected at high-volume centers, although the ORs are not significant for each illness severity category. Insurance status was not a significant predictor of resection at a high-volume center.
Table 4

Logistic Regression Analysisa

Factor

Odds Ratio

95% Confidence Interval

Age group

 18–44 years

1.00

 45–54 years

0.88

0.65–1.81

 55–64 years

0.75

0.56–1.00

 65–74 years

0.75

0.53–1.06

 >74 years

0.51

1.00–1.12

Year of diagnosis

1.07

1.02–1.13

Distance to nearest high-volume hospital (by 10 mile increment increases)

0.93

0.92–0.94

Gender

 Male

1.00

 Female

0.86

0.72–1.03

Race/Ethnicity

 Non-Hispanic White

1.00

 Non-Hispanic Black

0.79

0.59–1.06

 Hispanic

0.58

0.46–0.74

 Other

1.14

0.80–1.60

Insurance type

 Uninsured

1.00

 Medicare/Medicaid

1.43

0.96–2.14

 Other insurance

1.18

0.82–1.70

Severity of illness

 Score = 1

1.00

 Score = 2

1.20

0.78–1.85

 Score = 3

1.56

1.01–2.41

 Score = 4

1.20

0.77–1.81

Diagnosis

 All other diagnoses

1.00

 Periampullary adenocarcinoma

0.68

0.56–0.83

Admission type

 Elective

1.00

 Emergent

0.39

0.32–0.48

Type of operation

 Pancreaticoduodenectomy

1.00

 Distal pancreatectomy

0.53

0.41–0.69

 Pancreatectomy not otherwise specified

0.66

0.45–0.95

aModels the probability of undergoing resection at a high-volume center. OR > 1, increased likelihood; OR < 1, decreased likelihood

We tested for interactions between “distance to a high-volume hospital” and other covariates, and none were significant. As no significant interactions were identified, we did not stratify patients by distance in the multivariate models.

Discussion

Regionalization of medical and surgical procedures, especially those procedures that involve large costs and require considerable technical and professional skills, can be expected to improve the quality of medical care and save money. However, the benefits of regionalization must be weighed against the potential detriments including inconvenience to patients (increased travel costs, loss of time from work, constraints on the places where one can receive care),20 the potential for overwhelming of high-volume centers, increased mortality at low-volume hospitals as a result of regionalization, the decreasing quality of urgent related procedures at low-volume hospitals, and reduced access to surgical care if low-volume hospitals cannot recruit qualified surgeons.14

As discussed in his editorial, Birkmeyer14 points out that these concerns are “not very persuasive in the case of pancreaticoduodenectomy” or pancreatic resection in general. Pancreatic resection is an ideal model for regionalization of care for several reasons. First, there is a well-demonstrated, strong volume–outcome relationship. Second, the volume of pancreatic resections performed in this country in a given year are low enough such that high-volume centers would not be overwhelmed. Similarly, the volume lost from shifting these procedures away from low-volume centers would not be detrimental to the low-volume centers, as they occur so infrequently and often cost the hospitals money.

In Texas, the regionalization of pancreatic resection has improved between 1999 and 2004. Of the patients, 54.5% had their pancreatic resection performed at a high-volume center (>11 cases/year) in 1999, and this percentage increased to 63.3% by 2004. This extent of regionalization of pancreatic resection to high-volume centers is similar to the rates seen elsewhere.1,3,6,7,21 The studies are difficult to compare as the volume cutoffs vary. In a 2000 paper by Gouma and colleagues,7 40% of patients were resected at a hospital performing fewer than five pancreatic resections per year. Likewise, in a Maryland study by Gordon et al,1 45.9% of patients were resected at hospitals performing fewer than 20 resections per year. Worse, in a 2003 study of the California and Florida data by Ho and colleagues,3 77% of resections were performed in hospitals doing fewer than 10 resections per year. The Netherlands experience has been similar, with 65% of patients in 1994–1995 undergoing surgery at centers performing 10 or fewer resections per year. In the Netherlands, a plea for regionalization was made, but they were only able to decrease the percentage of patients resected at low-volume centers (<10 cases/year) to 57% in the time period 2000–2003. In a 2002 analysis of the Nationwide Inpatient Sample (NIS),6 the mean number of resections performed at any given hospital in the sample was only 1.5 cases per year. In a more recent analysis of the NIS,21 34.4% of patients were resected at a hospital performing fewer than five resections per year.

Whereas regionalization has increased significantly over the time period of the study, it is still a matter of concern that 26.6% of pancreatic resections in Texas in 2004 were performed at centers doing fewer than five cases per year, and 36.7% were performed at hospitals doing 10 or fewer resections per year. In addition, 19% of patients who were operated on at a low-volume center traveled farther than the distance to the nearest high-volume center.

We also observed interesting geographic patterns in the likelihood of traveling to high-volume centers (see Fig. 5), which are likely applicable to the United States as a whole. The 14 high-volume providers are located in six of Texas’s 254 counties: Dallas, Tarrant, Bell, Harris, Bexar, and Galveston. However, within these counties, high-volume centers have varying levels of monopoly, with people living in Galveston, Bell, and Dallas counties being the most likely to get resected at high-volume centers. The dip and then rise in percentage of patients undergoing resection at a high-volume center based on distance seen in Fig. 4 is likely real. We theorize that big counties with high-volume providers also generate more low-volume providers. As a result, they may be more likely to go to or be referred to one of these providers. However, in the mid-distance suburbs, where fewer low-volume providers exist, referring physicians may be more likely to tell patients that they don’t do such complex procedures and refer them to the high-volume centers in surrounding counties. Therefore, both distance, and referral patterns affect the extent of regionalization.

Outside the principal counties, there are four different situations: (1) suburban rings around the principal counties, (2) middle distance places (such as Texarkana, east Texas, Austin Hill County), (3) remote places (such as south Texas and San Angelo), and (4) very remote west Texas. For the suburbs and middle-distance places, the existence of a local middle-volume provider is key (5–10 cases/year). For example, in Brownsville (South Texas) there is no middle-volume provider. As a result, Brownsville patients are more likely to travel to high-volume providers. McAllen, close to Brownsville, has a middle-volume provider, and few of their people travel to high-volume hospitals. In addition, Brownsville does not refer to McAllen despite its proximity. Beaumont, in East Texas, has a similar situation to Brownsville, with no middle- or high-volume provider, and these patients tend to travel. From San Angelo west, low-volume providers in El Paso, San Angelo, and Lubbock monopolize the market. Here, the very long distance to high-volume providers seems to be a key factor.

Many studies use quartiles or quintiles to establish the volume cutoffs so as to have equal group sizes for statistical analysis when comparing outcomes such as in-hospital mortality, charges, and lengths of stay. For our analysis, we chose to use the Leapfrog group’s minimal volume cutoff for pancreatic surgery to evaluate the extent of regionalization, as this is the current recommendation by a large coalition of payers. Based on the definition we used for “high-volume”, only two hospitals shared the time period with fewer than 11 cases per year, but met the high-volume criteria. Several cities within Texas have middle-volume providers that do not meet the minimum volume requirements, but are clearly referral centers for the geographic area (e.g., Tyler, Lubbock). In these areas, concentration of patients from surrounding very low volume centers would likely bring these centers up to minimum volume standards.

Although we based our volume standards on all resections performed in the state, we eliminated patients who were not from Texas in analyzing the trends in regionalization (although these resections were included in determining a hospital’s volume status). By virtue of the fact that these patients traveled out of state (or country) to have the procedure performed, it is implied that they were an inherently different group of patients. There is also a potential for bias if patients in Texas traveled to nearby cities outside of the state to have their pancreatectomy performed, which we cannot identify. For example, it may be closer for patients in west Texas to travel to Denver, Albuquerque, or Oklahoma City instead of an in-state high-volume provider.

Despite the evidence that regionalization of pancreatic resection is warranted, Texas (and likely other states) are only achieving partial regionalization of care, with greater then 25% of patients being operated on at low-volume centers. In the multivariate analysis of the Texas Data, Hispanic patients were less likely to be resected at high-volume centers. This may be a result of a lack of education regarding the importance of volume for this procedure to this largely Spanish-speaking or bilingual population. The same was not true for Blacks. Older age also seemed to be a barrier to regionalization. Older people may be more reluctant to travel even a minimally further distance to get the best care. However, in the elderly population it is even more critical for the procedure to be performed at high-volume centers so as to minimize complications.

Patients with a diagnosis of periampullary cancer were less likely to be resected at high-volume centers, despite the fact that the highest volume center in Texas is a designated cancer center. This may be the result of hurried decision making and concern of delay when this uncommon diagnosis is made at low-volume centers. The same holds true for emergent procedures, which are far more likely to occur at low-volume centers. Especially in patients with cancer, regionalization to specialized centers will improve both their short- and long-term outcomes. Moreover, there are very few urgent or emergent indications for pancreatic resection and such resections should be minimized.

One of the biggest barriers to regionalization seems to be the distance to a high-volume center. Interestingly, this distance need not be great to influence the choice of hospital. Using the Medicare claims data, Birkmeyer et al.22 have demonstrated that, if not set too high, hospital volume standards could be implemented without imposing unreasonable travel burdens on individuals. This is true for the Texas Discharge Data with a cutoff of 11 or more procedures per year, as 75% of patients live within 75 mi of a high-volume center. However, our study demonstrates that even when the excess travel distance required for surgery at a high-volume center is short, many patients do not go to the high-volume centers. The etiology, however, is unclear, and both patient preference and referral patterns (such as those observed in Brownsville and McAllen) likely influence whether patients go to high-volume centers.

Texas serves as a good model for the regionalization of pancreatic resection. Unlike smaller states in which all patients can easily travel to a high-volume center, Texas is large with many rural areas distant from high-volume centers and would serve as a good model for regionalization to the high-volume centers throughout the U. S. Our data demonstrate that regionalization is feasible and the detailed analysis of the barriers to successful regionalization will aid in achieving this goal. To succeed in regionalizing care for pancreatic resection, we need to change referral patterns such that the 34% of patients living within 75 mi go to high-volume versus low-volume centers. In cities throughout the Texas or the U.S. with medium volume referral centers, cases done by very low-volume providers need to be concentrated at these medium-volume providers. In addition, we can help implement process measures at middle-volume centers that improve outcomes to the level of the high-volume centers (if needed), thereby removing the travel burden for patients.

Most of the volume–outcomes literature focuses on mortality as the endpoint. Although volume is clearly important for good outcomes after pancreatic resection, it is not the whole picture. A recent study by Meguid and colleagues23 demonstrated that volume explained less than 2% of the variance in the data on perioperative death after pancreatic resection. Other endpoints such as length of stay and total charges are also available in some of the published studies, but data on complication rates, morbidity rates, and readmission rates are not readily available. The next step is to further examine “high-volume” providers and measure outcomes more specifically, including the evaluation of common complications after pancreatic surgery including pancreatic fistula,2433 delayed gastric emptying,2427,34 intraabdominal abscess formation,2427 wound infections, bleeding, and others. The goal would then be to standardize care at high-volume institutions through the implementation of critical pathways (which focus on the process measures in the care of patients) designed based on the practices at the institutions with the best outcomes. These data need to be made widely available such that referring physicians, payers, and patients can make informed decisions regarding where to have their pancreatic surgery performed.

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© The Society for Surgery of the Alimentary Tract 2007