# Pancreaticoduodenectomy: Volume is not Associated with Outcome within an Academic Health Care System

Authors: Micheal T. Schell; Anthony Barcia; Austin L. Spitzer; Hobart W. Harris
Journal: HPB Surgery
 (2008)

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## Abstract

Hypothesis. Smaller and lower-volume hospitals can attain surgical outcomes similar to high-volume centers if they incorporate the expertise and health care pathways of high-volume centers. Setting. The academic tertiary care center, Moffit-Long Hospital (ML); the community-based Mount Zion Hospital (ZION); the San Francisco County General Hospital (SFGH); and the Veterans Affairs Medical Center of San Francisco (VAMC). Patients. 369 patients who underwent pancreaticoduodenectomy between October 1989 and June 2003 at the University of California, San Francisco (UCSF) affiliated hospitals. Interventions. Pancreaticoduodenectomy. Design. Retrospective chart review. To correct for the potentially confounding effect of small case volumes and event rates, data for SFGH, VAMC, and ZION was combined (Small Volume Hospital Group; SVHG) and compared against data for ML.
Main Outcome Measures. Complication rates; three-year and five-year survival rates. Results. The average patient age and health, as determined by ASA score, were similar between ML and the SVHG. The postoperative complication rate did not differ significantly between ML and the SVGH (58.8% versus 63.1%). Patients that experienced a complication averaged 2.5 complications in both groups. The perioperative mortality rate was 4% for patients undergoing pancreaticoduodenectomy at either ML or the SVGH. Although the 3-year survival rate for patients with adenocarcinoma of the pancreas was nearly twice as high at ML (31.2% versus 18.3% at SVHG), there was no significant difference in the 5-year survival rates (19% at ML versus 18.3% at SVHG). Conclusions. Low-volume hospitals can achieve similar outcomes to high-volume tertiary care centers provided they import the expertise and care pathways necessary for improved results.


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## Body

## 1. Introduction

Pancreaticoduodenectomy is the only
potentially curative treatment for pancreatic cancer, which ranks fifth in
cancer-related mortality worldwide [1–4].
However, because pancreatic cancer usually presents late, only 10% to
20% of patients are candidates for pancreaticoduodenectomy [5, 6], a
potentially lifesaving procedure that is associated with high morbidity and a
disappointing 5-year survival rate of 10% to 29% [7–12].Evidence showing better outcomes
after complex surgical procedures such as pancreaticoduodenectomy in
high-volume hospitals has led to the suggestion that these procedures are regionalized
to high-volume institutions [13–17].
However, although  better outcomes
have been attributed to a high volume of pancreaticoduodenectomies specifically
[18–20], some believe that it is a high volume of complex procedures performed
at a high-volume hospital, and  not
necessarily a specific procedure itself that is responsible for better outcomes
[21].  We also believe that it is the
high volume of complex procedures performed at academic tertiary referral
centers that enables them to optimize their operative and perioperative health care
delivery systems to achieve better outcomes.
We, therefore, hypothesized that if the optimized health care delivery
systems of high-volume hospitals were exported to smaller, low-volume hospitals,
their outcomes  would approximate those
of larger, high-volume hospitals. To examine this hypothesis, we
retrospectively analyzed the surgical and survival outcomes for patients
treated with pancreaticoduodenectomy at the low- and high-volume hospitals
affiliated with the University of California, San Francisco.


## 2. Methods

### 2.1. Data Source

This was a retrospective chart review
of 369 patients treated within the hospitals affiliated with the University of
California, San Francisco (UCSF)  from
October 1989 to June 2003.  The hospitals
include the academic tertiary care center, Moffit-Long Hospital (ML,n=301),
which averaged 23 pancreaticoduodenectomies per year; the Veterans Affairs
Medical Center of San Francisco (VAMC, n=41), which averaged 3 pancreaticoduodenectomies
per year; and the community-based Mount Zion Hospital (ZION, n=9) and the San
Francisco County General Hospital (SFGH, n=18), each of which averaged approximately
1 pancreaticoduodenectomy per year.
Patients were identified by using discharge codes for pancreatectomy
(52.51, 52.53, 52.6, 52.7) from the International Classification of Diseases,
Ninth Revision, Clinical Modification (ICD-9), and Current Procedural
Terminology (CPT) codes for the Whipple-type procedure with pancreaticojejunostomy
(48150) and without pancreaticojejunostomy (48152), the pylorus-sparing
Whipple-type procedure with pancreatojejunostomy (48153) and without
pancreatojejunostomy (48154), as well as total pancreatectomy (48155).  Followup data was obtained through the cancer
registry of each institution.  At the
time of the study, 184 patients had died, 9 were lost-to-followup, and the
remaining 176 had been monitored for an average of 5.0±3.7 years (mean ± SD).  This study was approved by the UCSF Committee
on Human Research and by the individual Institutional Review Boards at all
hospitals where applicable.


### 2.2. Outcome Variables

Patient demographics and relevant
patient history including age, sex, date of birth, race, and co-morbidities
were documented.  Inpatient variables
included the date of procedure, complications, length of stay in the intensive
care unit (ICU) and hospital, and disposition after discharge.  We also recorded data regarding the
indication for surgery, the American Society of
Anesthesiologists (ASA) risk score, the type of resection (pylorus-
preserving versus classic; distal gastrectomy), the extent of pancreatic
resection, whether the superior mesenteric vein was resected, intraoperative
blood loss, the incidence and number of blood transfusions, and operative
time.  Pathology data consisted of tumor
site of origin, tumor differentiation and diameter, resection margins, and
evidence of perineural or vascular invasion.
Perioperative mortality (defined as death in hospital or within 30 days
of discharge) and long-term survival were ascertained for patients seen at the
four hospitals.


### 2.3. Statistical Analysis

The Kruskal-Wallis test was used to
compare the mean and median values of continuous data. Fisher's exact test was used to evaluate statistical
significance for categorical data.
Significance was set atP≤.05.
The Kaplan-Meier method was used to calculate three-year and five-year
survival curves, which were compared using the log-rank test. To correct for the potentially confounding effect
of small case volumes and event rates, data for SFGH, VAMC, and ZION was
combined (Low Volume Hospital Group; LVHG) and compared against data for
ML.


## 2.1. Data Source

This was a retrospective chart review
of 369 patients treated within the hospitals affiliated with the University of
California, San Francisco (UCSF)  from
October 1989 to June 2003.  The hospitals
include the academic tertiary care center, Moffit-Long Hospital (ML,n=301),
which averaged 23 pancreaticoduodenectomies per year; the Veterans Affairs
Medical Center of San Francisco (VAMC, n=41), which averaged 3 pancreaticoduodenectomies
per year; and the community-based Mount Zion Hospital (ZION, n=9) and the San
Francisco County General Hospital (SFGH, n=18), each of which averaged approximately
1 pancreaticoduodenectomy per year.
Patients were identified by using discharge codes for pancreatectomy
(52.51, 52.53, 52.6, 52.7) from the International Classification of Diseases,
Ninth Revision, Clinical Modification (ICD-9), and Current Procedural
Terminology (CPT) codes for the Whipple-type procedure with pancreaticojejunostomy
(48150) and without pancreaticojejunostomy (48152), the pylorus-sparing
Whipple-type procedure with pancreatojejunostomy (48153) and without
pancreatojejunostomy (48154), as well as total pancreatectomy (48155).  Followup data was obtained through the cancer
registry of each institution.  At the
time of the study, 184 patients had died, 9 were lost-to-followup, and the
remaining 176 had been monitored for an average of 5.0±3.7 years (mean ± SD).  This study was approved by the UCSF Committee
on Human Research and by the individual Institutional Review Boards at all
hospitals where applicable.


## 2.2. Outcome Variables

Patient demographics and relevant
patient history including age, sex, date of birth, race, and co-morbidities
were documented.  Inpatient variables
included the date of procedure, complications, length of stay in the intensive
care unit (ICU) and hospital, and disposition after discharge.  We also recorded data regarding the
indication for surgery, the American Society of
Anesthesiologists (ASA) risk score, the type of resection (pylorus-
preserving versus classic; distal gastrectomy), the extent of pancreatic
resection, whether the superior mesenteric vein was resected, intraoperative
blood loss, the incidence and number of blood transfusions, and operative
time.  Pathology data consisted of tumor
site of origin, tumor differentiation and diameter, resection margins, and
evidence of perineural or vascular invasion.
Perioperative mortality (defined as death in hospital or within 30 days
of discharge) and long-term survival were ascertained for patients seen at the
four hospitals.


## 2.3. Statistical Analysis

The Kruskal-Wallis test was used to
compare the mean and median values of continuous data. Fisher's exact test was used to evaluate statistical
significance for categorical data.
Significance was set atP≤.05.
The Kaplan-Meier method was used to calculate three-year and five-year
survival curves, which were compared using the log-rank test. To correct for the potentially confounding effect
of small case volumes and event rates, data for SFGH, VAMC, and ZION was
combined (Low Volume Hospital Group; LVHG) and compared against data for
ML.


## 3. Results

The average patient age and health,
as determined by ASA score, were similar, though the sex and race of the
patient populations were significantly different between ML and the LVHG (Table1).  Although the most common indication
for surgery at ML (50.2%) and LVHG (51.7%) was pancreatic cancer (Figure 1),
there was significant variation between the groups.  Pylorus-preserving procedures were performed
more often than classic distal gastrectomy procedures both at ML (64.7% versus
35.3%) and LVHG (56.1% versus 43.9%) without a significant difference in the
rates (Table 2).  Superior mesenteric
vein resection was performed in 9% of patients in both groups.   Although average blood loss differed
significantly between ML and LVHG, the transfusion rate and average number of
transfused units of blood in patients requiring transfusion did not.  Total operative time and length of stay in
the ICU and in the hospital were significantly shorter at ML than at the LVHG
(Table 2).Table 1
Characteristics of patients who underwent pancreaticoduodenectomy at UCSF-affiliated hospitals,
1989–2003.
CharacteristicsMLLVHGP value†Age, mean (median), year61 (64)62 (62).887Sex, no. (%)‡——<.0001Male153 (50.8)59 (86.8)—Race, no. (%)‡——<.0001Asian33   (11)7  (10.4)—African american8 (2.7)13 (19.4)—Hispanic17 (5.6)5  (7.5)—Caucasian206 (68.4)37  (55.2)—Other37 (12.3)5  (7.5)—ASA Rating, no. (%)‡——.60514 (1.3)1 (3.8)—2142 (47.8)12 (46.2)—3148 (49.8)13 (50)—43 (1)0 (0)—†According to the Kruskal-Wallis test for continuous data or
Fisher's exact test for categorical data.‡Numbers may not sum to group total because data was
not available for all patients.Table 2
Operative and perioperative characteristics of patients who underwent pancreaticoduodenectomy
at UCSF-affiliated hospitals, 1989–2003.
CharacteristicsMLLVHGP value†Procedure
type, no. (%)——.206Pylorus-preserving194 (64.7)37 (56.1)—Classic; distal gastrectomy106 (35.3)29 (43.9)—Vein
resection, no. (%)——1.000No.274/301 (91)52/57 (91.2)—Blood
loss, mean (SD), ml1166.7 (1410.7)1262.7 (836.7).012Patients
receiving a transfusion, no. (%)134/301 (44.5)29/53 (54.7).1813Units
transfused, mean (SD)3.3 (3.9)2.6 (1.3).930Operative
time, mean (SD), h6.7 (2)8.3 (2.1)<.0001ICU stay,
mean (SD), days2.1 (7)8.8 (21.6)<.0001Post-Op     hospital stay, mean (SD), days16.1 (23.5)24.5 (24)<.0001†According to the Kruskal-Wallis test for continuous data or Fisher's exact test for categorical data.Figure 1
Indication for pancreaticoduodenectomy at UCSF-affiliated hospitals,
1989–2003.  ML, Moffit-Long Hospital; LVHG, low-volume hospital group, is the
combined data for San Francisco County General Hospital, Veterans Affairs
Medical Center of San Francisco, and Mount Zion Hospital (P=.003 by
Fisher's exact test).The postoperative complication rate
did not differ significantly between ML and the SVHG (58.8% versus 63.1%, Table3).  The average number of complications
per patient, among those that experienced a complication, was 2.5.  Only
cardiopulmonary complications
occurred at a significantly different rate,  and were the most frequent complication in
each group.Table 3
Complications in patients who underwent pancreaticoduodenectomy at UCSF-affiliated hospitals, 1989–2003.
ComplicationsML
(n=301)LVHG
(n=68)P value†Complication, no. (%)177 (58.8)41 (60.3).579Complications per patient, mean (SD)2.5  (2.6)2.5 (1.8).221General types of
complications, no. (%)———Cardiopulmonary52 (17.3)20 (29.4).028Wound41 (13.6)10 (14.7).846Pancreatic leak or fistula38 (12.6)4 (5.9).140Secondary procedures23 (7.6)8 (11.8).330Postoperative hemorrhage19 (6.3)3 (4.4).778Enteric leak, fistula, or stricture10 (3.3)1 (1.5).697Delayed gastric emptying14 (4.7)4 (5.9).754Reoperation22 (7.3)8 (11.8).224†According to Fisher's exact test for categorical data.The pancreas was the most common site
of tumor origin in both groups (Figure2).
Tumor pathology was similar in both groups; adenocarcinoma accounted for
approximately 67–69% of the cases (Figure 3).  The average tumor diameter, the incidence of
positive margins, and the percentages and patterns of patients with a low,
moderate, or high grade of tumor differentiation did not differ significantly
between LVHG and ML, but neural invasion did (Table 4).Table 4
Pathologic diagnosis in patients who underwent pancreaticoduodenectomy at UCSF-affiliated hospitals, 1989–2003.
CharacteristicsMLLVHGP value†Tumor diameter, mean
(SD), cm3.0 (1.5)2.9 (1.7)1.000Tumor differentiation,
no. (%)‡——.575Low36 (39.1)7 (30.4)—Moderate46 (50)12
(52.2)—High10 (10.9)4
(17.4)—Positive tumor
margins, no. (%)25 (26.9)6 (25)1.000Positive vascular
invasion, no. (%)28 (31.1)7
(58.3).102Positive neural
invasion, no. (%)54 (60)14 (87.5).047†According to the Kruskal-Wallis test for continuous data or Fisher's exact test for categorical data.‡Numbers may not sum to
group total because data was not available for all patients.Figure 2
Pathological tumor site for patients undergoing pancreaticoduodenectomy
at UCSF-affiliated hospitals, 1989–2003.  ML, Moffit-Long Hospital;
LVHG,  low-volume hospital group, is the
combined data for San Francisco County General Hospital, Veterans Affairs
Medical Center of San Francisco, and Mount Zion Hospital (P=.201 by
Fisher's exact test).Figure 3
Pathological tumor type for patients undergoing pancreaticoduodenectomy
at UCSF-affiliated hospitals, 1989–2003.  ML, Moffit-Long Hospital;
LVHG,  low-volume hospital group, is the
combined data for San Francisco County General Hospital, Veterans Affairs
Medical Center of San Francisco, and Mount Zion Hospital; IPMN, Intraductal
Papillary Mucinous Neoplasm (P=.202 by Fisher's exact test).The perioperative mortality rate for
patients undergoing pancreaticoduodenectomy was approximately 4% in both groups
(not shown).  Although the 3-year
survival rate for patients with adenocarcinoma of the pancreas was nearly twice
as high at ML (31.2% versus 18.3% at LVHG, Figure4), there was no significant
difference in the 5-year survival rates
(19% at ML versus 18.3% at LVHG).Figure 4
Comparison of Kaplan-Meier survival curves for patients with
adenocarcinoma of the pancreas.  The
survival data from Mount Zion hospital, San Francisco General County hospital,
and the Veterans Affairs Medical Center were combined (LVHG) and compared with
data from Moffitt-Long Hospital (ML).  (P=.035 at 3 years; P=.096 at 5
years, by Log-Rank test).


## 4. Discussion

Our results demonstrate that
morbidity and mortality outcomes were consistent between the low-volume and
high-volume hospitals affiliated with UCSF.
We believe that this is due to the sharing of operative techniques and
perioperative care pathways, which has enabled the low-volume hospitals to
develop a health care delivery system that resembles the large-volume hospital
and achieves comparable results.The low-volume hospital group, which
consisted of a community-based hospital and a county general hospital, each of
which averaged 1 pancreaticoduodenectomy per year, and a Veterans Affairs
Medical Center that averaged 3 pancreaticodudenectomies per year, was able to minimize
adverse events to the same extent as the large-volume tertiary center, which
averaged 23 pancreaticodudenectomies per year.
The hospitals did not differ significantly in the percentage of patients
experiencing a complication.  In fact,
the mean and median numbers of complications among patients who had a
complication were exactly the same.
Moreover, the pancreatic fistulas and anastomotic leaks that are often
associated with longer hospitalizations and increased mortality occurred at
statistically equivalent lower rates (12.6 % at ML and 5.9% in the LVHG)  than
the internationally reported average of 14.3%–26.7% [23].  Uniform patient selection among the hospitals
likely aided in the eventual similar outcomes, because although racial and
gender differences existed between the LVHG and ML, the general health and age
of the patients were similar.Clinic notes and information obtained
through the appropriate cancer registries showed a median followup of 5.0 and
5.9 years at ML and the LVHG, respectively.
Although there are inherent limitations to a retrospective chart review,
we believe that the prolonged followup period allows us to accurately ascertain
the long-term survival through our methods.
For all patients who underwent pancreaticoduodenectomy for any
indication, perioperative mortality and five-year survival did not differ
significantly between the SVGH and ML.
In addition, for patients who underwent pancreaticoduodenectomy for
adenocarcinoma of the pancreas either at the LVHG or ML,  the perioperative
mortality and five-year survival rates were similar and comparable to the
nationally reported rates of 3%–11% and 10%–29%, respectively [7–12, 22].   However,   in our study, as in
others, there was a significant difference between the low- and high-volume
hospitals in the three-year survival rate for patients treated with
pancreaticoduodenectomy for adenocarcinoma of the pancreas [1–4].  Further investigation into postoperative care
pathways and procedural capabilities that may account for the early disparity
in survival is clearly warranted.The average operative time in the
LVHG was significantly longer than at ML, as was the average blood loss
(although only by 96 cc).   The clinical
importance of an additional blood loss of 96 cc is pedagogical at best, and is
further diminished by our finding that the percentage of patients requiring a
transfusion and the average number of units transfused in such patients were
similar among the groups.   The difference
in operative time may reflect the advantage that a high volume of cases gives a surgical team in terms of operative
efficiency. However, since the rate and number of units transfused, the
perioperative mortality, the rate and average number of complications, and the
5-year survival rates were not significantly different between the LVHG and ML,
operative efficiency did not seem to affect efficacy.The greater efficiency in the health
care system at ML was also reflected in the significantly shorter stays in both
the ICU and the hospital.  Although we
cannot establish a causal relationship, we believe the longer hospital stays in
the LVHG were most likely influenced by the extended ICU stays.  Perhaps the inability of the LVHG to provide
the necessary care and observation outside the ICU was a factor in the
increased length of stay, but further studies are needed to assess whether
there is a significant disparity between the technical capabilities of the LVHG
and ML.  More importantly, if there are
important differences in staff or resource capabilities that could be
identified and corrected, perhaps the LVHG, as well as other small and
low-volume hospitals, could achieve ICU and hospital stays which approximate
those of high-volume hospitals.Optimal long-term surgical outcomes
were achieved at the hospitals affiliated with UCSF.  For several reasons we believe that these
outcomes indicate that health care delivery systems similar to ours can produce
comparable results, independent of the volume of pancreaticoduodenectomies
performed.  First, UCSF residents rotate
through all the affiliated hospitals and may transmit or share knowledge gained
at the tertiary care center (ML) on how to preoperatively evaluate patients,
assist at and perform a pancreaticoduodenectomy, and recognize potential postoperative
complications.  Secondly, the affiliated
hospitals all participate in the UCSF morbidity and mortality education system,
which serves to enlighten the surgeons and the ancillary services such as
anesthesia, interventional radiology, and nursing.  Lastly, expert surgeons and case-related
specialists often travel between hospitals to aid in preoperative assessment
and the technical aspects of the cases.
We consider the low-volume hospitals to be independent institutions that
are capable of importing the critical elements of a successful health care
delivery system in order to increase the health care options of patients in
their surrounding communities.  Perhaps
the best way to improve access to and the outcomes of complex surgical procedures
for the majority of the population in the United States is to develop specific programs
in selected low-volume centers that would be affiliated with, modeled after,
and thus effectively emulate the practices and processes evident in high-volume
hospitals.  Despite the intuitive appeal
of regionalizing the performance of complex surgical procedures, there are
several barriers, including patient preference, that limit the practical
utility of this approach.  Still, one
cannot overemphasize the essential importance of low volume hospitals implementing
detailed, comprehensive programs in order to safely provide high-quality,
complex surgical services.  By identifying,
exporting, and implementing the operative decision making and perioperative
care pathways that enable high-volume centers to achieve consistently good
outcomes into small and low-volume hospitals,  their outcomes should approximate
those of the high-volume centers.  We are
encouraged by our early experiences achieving just such a goal in a local,
county medical center in Northern California [22].



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