（ 59 ）Refereed

The implications of success rewards on complications and lengthof hospital stay: A retrospective study on esophageal cancer
patients following esophagectomy

Hiroki Konno
Abstract
Background: In Japan, the medical fee system for acute care（Diagnosis Procedure Combination/Per
Diem Payment System（DPC/PDPS））does not incentivize improvements in the quality of surgery.
This retrospective study aimed to clarify the necessity of success rewards for reducing complications
in patients who underwent esophagectomy and analyze the eﬀects of complications from surgery on
hospital stay.
Methods: This study analyzed 67 in-patients who underwent esophagectomy between June 2004 andDecember 2008. Stepwise multiple regression analysis to estimate the effect of complications on
hospital stay and survival analysis using the Kaplan-Meier estimate were performed to estimate thecumulative probability of hospital stay.
Results: The mean hospital stay was 45.84±31.16. Of these patients, 4.5% had anastomotic stricture
as a complication. Stepwise multiple regression analysis revealed that the occurrence of anastomoticstricture prolonged the length of hospital stay by 58.4%（P＜0.01）. Survival analysis revealed thatthe cumulative probability of hospital stay for the positive group with anastomotic stricture wassigniﬁcantly higher than that for the negative group.
Conclusion: These findings could help the government redesign the DPC/PDPS introduced foreasing medical fee payment for acute care. The results indicate the need to provide additional
success rewards to improve the quality of surgery.
Key word: esophagectomy, anastomotic stricture, DPC/PDPS, survival analysis
Ⅰ．Introduction
It has been 18 years since the Diagnosis Procedure Combination/Per Diem Payment System（DPC/PDPS）was introduced in Japan as the national system of medical fee payment for acute care.
This system was developed as a tool for standardizing and ensuring the transparency of medical
information to provide insights into the quality of medical treatment and hospital management1. As aresult, the introduction of the DPC/PDPS accelerated the standardization of costs and processes− 37 −

（ 60 ）KEIZAI SHUSHI

Vol. 91

No. ２

related to acute care medical treatments in Japan.
However, the prognosis of medical treatments involving highly invasive surgery is often
exacerbated by complications, as is the case of esophagectomies. The main complications following
esophagectomy are caused by pneumonia or anastomotic leakage2-4. Particularly, the incidence ofanastomotic stricture after esophagectomy is caused by anastomotic leakage associated with either
obstruction of blood ﬂow at the anastomotic site or inadequate anastomosis techniques5. Nevertheless,the DPC/PDPS system does not have a framework to incentivize acute care hospitals to improvedirectly the quality of surgery related to esophageal cancer. The DPC/PDPS system is merely amechanism that indirectly improves the quality of acute care by providing incentives for patients tobe discharged early.
Considering this, a system of success rewards for successful surgical outcomes will lead to
improved quality of surgery because it constitutes adequate fees. Acute hospitals that can perform
high-quality surgeries will aggressively perform surgical cases if they can obtain appropriate fees for
successful surgical outcomes. As a result, the surgical volume will increase in such hospitals, thusincreasing surgeon experience and further improving surgical quality. The phenomenon of creamskimming is unlikely to occur when the risk of surgical complications is inherently unavoidable,
such as with esophagectomy. This retrospective study aimed to clarify the necessity of successrewards to incentivize high-quality surgery for patients who have undergone esophagectomy.
Particularly, this study analyzed the eﬀects of three related complications̶pneumonia, anastomotic
leakage, and anastomotic stricture̶on the length of hospital stay for patients. This study suggeststhat the provision of additional success rewards is necessary to encourage superior surgicaloutcomes.
Ⅱ．Methods
1. Study design and subjects
Data on 67 in-patients（male: n＝64, female: n＝3）who claimed medical fees were reviewed. Data
were analyzed for patients who had undergone surgery for esophageal malignant tumors, including
gastrointestinal reconstruction surgery through operation of the neck, chest, and abdomen, asindicated by the medical fee code for a major diagnostic category of malignant tumors of theesophagus, including the neck.
The data for this study were collected from June 2004 to December 2008. This period represented
the initial stage of DPC/PDPS enforcement. It shows the correspondence of medical treatment witha new national medical service fee system after introduction of the DPC/PDPS. Thereby, the impactof the system changes might have had some impact on length of hospital stay. Although the data
were older, the diagnostic criteria remain fundamentally unchanged when esophagectomy isrequired6-7. The data included a full range of outcomes, from complete recovery to death. This study
used data collected from 12 hospitals and was approved by the ethics review board of theInternational University of Health and Welfare, Japan.
− 38 −

The implications of success rewards on complications and length of hospital stay: A retrospective study on esophageal cancer patients following esophagectomy（Konno） （ 61 ）2. Statistical analysis
The distribution of patients age profiles and length of hospital stay were analyzed using theKolmogorov-Smirnov test. Patients were divided into positive and negative groups of patientswith and without complications for each variable: pneumonia, anastomotic leakage, and anastomoticstricture. Pairwise comparisons of means for groups were conducted using Levene s test when equalvariance could be assumed and Welch s t-test when it could not.
Stepwise multiple regression analysis was performed to estimate the eﬀect of the three variableson the length of hospital stay. Moreover, additional modes of treatment（central intravenous injection,radiotherapy, and chemotherapy）deﬁned in the DPC/PDPS as the medical fee codes were included
as dummy variables. Regarding the level of severity, the pathologic stage was weighted as a dummy
variable because it includes the impact of patient factors on the length of hospital stay within theconstraints of data. The formula used for the estimation waslnDi＝α＋β1P＋β2AL＋β3AS＋β4CI＋β5RT＋β6CT＋β7S1＋β8S2＋β9S3＋β10S4＋εi.
where the independent variable D i was the length of hospital stay（natural logarithm）, thedependent variables were as follows: P was the pneumonia dummy, AL was the anastomotic leakage
dummy, AS was the anastomotic stricture dummy, CI was the central intravenous injection dummy,
RT was the radiotherapy dummy, CT was the chemotherapy dummy, S1 was the pathologic stage Idummy, S2 was the stage II dummy, S3 was the stage III dummy, S4 was the stage IV dummy, andεi was the error term. Each dummy variable was set to one if the independent variable wasapplicable. Multicollinearity was not observed.
Of these variables, survival analysis by the Kaplan-Meier estimate was used to estimate thecumulative probability of hospital stay for the group of patients with and without complications,which was statistically signiﬁcant. Pairwise comparisons of the respective groups of patients withand without complications for each variable were conducted using the log-rank test. The event forstarting to follow the patient was deﬁned as discharge from acute-care beds. Statistical analyses wereperformed using IBM SPSS Statistics for Windows, version 26.0. After stepwise multiple regression
analysis, power analysis was performed.
Ⅲ．Results
Of the in-patients analyzed, 260 were diagnosed with a malignant tumor in the esophagus,
including the neck that was coded as a major diagnostic category from June 2004 to December 2008.
They had undergone allied surgeries as well. Of these patients, 191（73.5%）had undergone
endoscopic esophageal mucosal resection, 67（25.8%）had undergone esophageal malignant tumor
surgery with gastrointestinal reconstruction surgery through operation of the neck, chest, andabdomen, and 3（1.2%）had undergone other operations. Esophagectomy with gastrointestinal
reconstruction surgery of the neck, chest, and abdomen has a higher risk of complications due to the− 39 −

KEIZAI SHUSHI（ 62 ）

Vol. 91No. ２highly invasive nature of the surgery. Of these patients, 11 patients underwent additional treatment
through central intravenous injection（1.5%）, radiotherapy（13.4%）,and chemotherapy（1.5%）.
Data regarding patients descriptive statistics as well as outcomes and pathologic stages are shownin Table 1. The average length of hospital stay tended to be inconsistent with aging（Figure 1）. The
peak of the length of hospital stay ranged between 22 days and 28 days, aggregated by each seventh

Table 1. Descriptive statistics of the subjects
Number of subjects

67

Age（average ± SD）

65.64±8.41

Age（range, Q1, Q3）

45-87, 60, 71.5

Male: Female ratio

64:3

Pathologic stage（n＝67）
Stage 0（n, %）0（ 0.0%）Stage I

16（23.9%）

Stage II

8（11.9%）

Stage III19（28.4%）

Stage IV6（ 9.0%）Blank18（26.9%）

Outcome（n＝67）
Cured（n, %）0（ 0.0%）

Improvement63（94%）

Remission0（ 0.0%）No change0（ 0.0%）

Worsening0（ 0.0%）

Death2（ 3.0%）

Death by other diseases

1（ 1.5%）

Others1（ 1.5%）

Length of hospital stay（average ± SD）

45.84±31.16

Length of hospital stay（range, Q1, Q3）

15-214, 27, 56

Complications（n＝67）
Pneumonia（n, %）2（ 3.0%）

Anastomotic leakage

3（ 4.5%）

Anastomotic stricture13（19.4%）

Additional treatment（n＝67）
Intravenous injection（n, %）1（ 1.5%）

Radiotherapy

9（13.4%）

Chemotherapy

1（ 1.5%）− 40 −

The implications of success rewards on complications and length of hospital stay: A retrospective study on esophageal cancer patients following esophagectomy（Konno） （ 63 ）day, while the mean and standard deviation were 45.84±31.16. According to statistics from thehospitals covered by DPC/PDPS nationwide in 2008, the mean and standard deviation were 59.15±35.23; thus, the representativeness of the data is generally secured8.
Figure 1. Frequency（n＝67）and ALS by age

Of the three complications̶pneumonia, anastomotic leakage, and anastomotic stricture̶theresults conﬁrmed that the average length of hospital stay of the positive group for anastomoticstricture was significantly longer than that of the negative group（P＜0.1）, while there were no
signiﬁcant diﬀerences in the diagnosis of pneumonia and anastomotic leakage between the groups（Table 2）. The result of the test for anastomotic stricture was slightly robust, and the results of thetests for pneumonia and anastomotic leakage did not present any diﬃculties because the samples
were small.
Table 2. Descriptive statistics of days by the occurrence group of complications
Variables ofComplications

Positive

Negative（1）nLength of Hospital Stayn

Length of Hospital Stay（1）PPneumonia

2

51.00± 4.24

65

45.68±31.62

0.81

（2）

Anastomotic leakage

3

45.00±13.08

64

45.88±31.80

0.96

（2）

Anastomotic stricture

13

70.08±51.51

54

40.00±20.72

0.06

*（3）

（1）Average ± SD,（2）Levene s test,（3）Welch s t-test, *p＜ .1

The eﬀect of the three complications on the length of hospital stay was estimated using a stepwise
method（Table 3）. As a result, the formula to estimate the length of hospital stay islnDi＝3.495＋0.46AS＋0.513RT＋1.205CT＋εi− 41 −

KEIZAI SHUSHI（ 64 ）

Vol. 91

No. ２

The eﬀects of anastomotic stricture, radiotherapy, and chemotherapy were found to be statisticallysignificant, while other factors, including the pathologic stage, were excluded. In addition,
exponentializing the unstandardized coeﬃcients showed that the incidence of anastomotic stricture
prolonged hospital stays by 58.4%.
Table 3. Estimated effect of complications on the length of hospital stay, adjusted R2: 0.30
βCoeﬃcientStandard Errort value

p value

Intercept3.495

0.065

53.666

Anastomotic stricture Dummy

0.460

0.139

3.313

＜0.01

***

Radiotherapy Dummy

0.513

0.161

3.189

＜0.01

***

Chemotherapy Dummy

1.205

0.453

2.660

＜0.05

**

***p＜ .01, **p＜ .05

Finally, the cumulative probability of hospital stay for patients with and without anastomoticstricture was calculated. The results conﬁrmed that the cumulative probability of hospital stay forthe positive group was signiﬁcantly higher than that for the negative group. The cumulative
probability of hospital stay in the positive group for anastomotic stricture was 92.3% on the 21stday, in contrast to 90.7% in the negative group（92.3%: 64.8% on the 28th day, 76.9%: 42.6% on the35th day, 53.8%: 33.3% on the 42nd day）
（Figure 2）.
Figure 2. Cumulative probability of hospital stay; Anastomotic stricture− 42 −

The implications of success rewards on complications and length of hospital stay: A retrospective study on esophageal cancer patients following esophagectomy（Konno） （ 65 ）Ⅳ．Discussion
In this study, the data on claims for medical fees for esophageal cancer in-patients following
esophagectomy were retrospectively analyzed to estimate the effect of three complications̶pneumonia, anastomotic leakage, and anastomotic stricture̶on the length of hospital stay.
The results conﬁrmed that the hospital stay of the positive group for anastomotic stricture wassignificantly prolonged by 58.4% compared to the negative group. In addition, the cumulative
probability of hospital stay for the positive group for anastomotic stricture was signiﬁcantly higher
than that for the negative group.
Previous studies have shown that the occurrence of anastomotic stricture after esophagectomy ismainly caused by anastomotic leakage, while a high risk of anastomotic stricture does not affectsurvival rate. A previous study showed that anastomotic stricture was signiﬁcantly associated withanastomotic leakage, while other perioperative factors, such as age, body mass index, preoperativetreatment, diabetes mellitus, hemoglobin A1c before surgery, amount of bleeding under operation,
pathologic stage, and pneumonia, were not5. Another study showed that only the occurrence ofpneumonia affected survival rate, although pneumonia（22.5%）, anastomotic leakage（19.4%）, and2
recurrent nerve paralysis（15.8%）occurred in patients who had undergone esophagectomy（n＝284）.

Previous studies have not shown a prolonging effect of hospital stay due to the occurrence ofcomplications. As expected, the results of this study showed that the occurrence of anastomoticstricture had a significant prolonging effect on the length of hospital stay; and radiotherapy andchemotherapy prolonged hospital stay for patients. Of these factors, the clinical features of patients
following radiotherapy and chemotherapy corresponded with those in the DPC/PDPS system,
because these therapies were speciﬁed in the DPC/PDPS as factors that prolonged hospital stay.
The results of this study are medically plausible because anastomotic stricture is caused by either
anastomotic leakage associated with obstruction of blood ﬂow in the anastomotic part or inadequate
anastomosis techniques5. The incidence rate of anastomotic stricture after esophagectomy wasreported to be about 5-34%, despite improvements to the suturing technique9.
It should be noted that the occurrence of anastomotic stricture has prolonged hospital stay by
58.4% in terms of the level of treatment and quality of surgeries. A previous study reported thatfactors such as the number of surgeons and surgical volume are important in reducing the risks ofesophagectomy4. However, it is not only a matter of increasing the number of surgeries. For example,
some of the data included those of stage IV patients following esophagectomy. The prognoses of suchpatients will not always be favorable in the long run.
Whether surgery should be performed depends on clinical judgment; however, it must be
premised that surgery can be performed using advanced procedures. Acute hospitals that provide
high-quality surgical services will be willing to perform surgery if they can obtain the appropriate
rewards for having the surgery performed. As a result, the number of surgeries will increase, andthe quality of surgeries will improve, which can be expected to shorten the length of hospital stay
− 43 −

（ 66 ）KEIZAI SHUSHI

Vol. 91

No. ２for patients. Therefore, by providing additional rewards for successful surgeries, the quality ofsurgery can be signiﬁcantly improved and patients can be expected to be discharged early. Thus, itis necessary to provide an additional reward for successful surgeries to enable high-quality surgery.
Ⅴ．Limitations
This study has several limitations. First, the outcomes of esophagectomy could have been
improved by introducing new suturing devices and robotic surgery. Therefore, the implications ofthese results are weakened. Second, anastomotic stenosis is not always caused solely by leakage ofthe anastomotic site. It may be caused by factors associated with patient health, such as diabetes
mellitus, arteriosclerotic diseases, hepatic cirrhosis, renal dysfunction, decreased respiratory function,and the eﬀects of consuming steroids5. Third, the results cannot be generalized for all populationgroups of Japan, therefore, it is necessary to re-examine the national data of Japan.
Ⅵ．Conclusion
This retrospective study analyzed the effects of three complications associated withesophagectomy̶pneumonia, anastomotic leakage, and anastomotic stricture̶on the duration ofhospital stay. As a result, the hospital stay of the positive group pertaining to anastomotic stricture
was signiﬁcantly prolonged compared to that of the negative group, and the cumulative probabilityof hospital stay of the positive group was signiﬁcantly higher than that of the negative group.
High-quality surgery that does not result in anastomotic stricture will improve patient prognosis.
It is necessary to increase the quality of surgery by setting up a system of granting success rewards
for superior quality surgery in the DPC/PDPS system. Thus, both hospitals and patients areexpected to gain beneﬁts.
Ⅶ．References［1］Matsuda S, Current State and Problems of Diagnosis Procedure Combination/Per-Diem Payment System inJapan , Journal of the Japan Society for Healthcare Administration, No.39（2）,2003, pp. 130-143.（in Japanese）［2］ Booka E, Takeuchi H, Nishi T, et al.,The Impact of Postoperative Complications on Survivals After

Esophagectomy for Esophageal Cancer , Medicine, No.94（33）,2015, p. e1369.
［3］Tsujimoto H, Hiraki S, Sakamoto N, et al., Infectious Complications After Surgery for Gastrointestinal Malignancy
Aﬀect the Clinical Outcome , The Japanese Journal of Gastroenterological Surgery, No.43（7）, 2009, pp. 704-709.（inJapanese）［4］Pennathur A and Luketich JD, Resection for Esophageal Cancer: Strategies for Optimal Management , The
Annals of Thoracic Surgery, No.85（2）,2008, pp. S751-S756.
［5］Koyanagi K, Ozawa S, Kazuno A, et al., Risk Factors and Prevention for Anastomotic Leakage and Stricture After
Esophagectomy for Esophageal Cancer , Surgery, No. 91（7）,2019, pp. 710-715.（in Japanese）［6］Ando N, Progress in Multidisciplinary Treatment for Esophageal Cancer in Japan , Journal of Japanese Society of− 44 −

The implications of success rewards on complications and length of hospital stay: A retrospective study on esophageal cancer patients following esophagectomy（Konno） （ 67 ）Gastroenterology, No.111（2）,2014, pp. 243-252.（in Japanese）［7］Kato H, Transition of Treatment for Esophageal Cancer , Japanese Society of Strategies for Cancer Research &Therapy, No.16（1）,2010, pp. 45-49.（in Japanese）［8］The Ministry of Health, Labor and Welfare,

Final report on Survey results and evaluation on the impact

assessment of DPC introduction , 2009, https://www.mhlw.go.jp/shingi/2009/05/s0514-6.html.
［9］Okamoto K, Ninomiya I, Maruzen S, et al., Three Cases of Removable Self-Expandable Metallic Stent Placement
Against Refractory Anastomotic Stenosis After Esophageal Cancer Resection , Gastroenterological Endoscopy, No.56（11）,2014, pp. 3792-3797.（in Japanese）− 45 −