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Original Paper
Dig Surg 2015;32:361–366
DOI: 10.1159/000433608
A Quantified Scoring System for Postoperative
Complication Severity Compared to the
Clavien-Dindo Classification
The Comprehensive Complication Index
AnnelijnE.Slaman SjoerdM.Lagarde SuzanneS.Gisbertz
MarkI.vanBergeHenegouwen
Department of Surgery, Academic Medical Center, Amsterdam , The Netherlands
Conclusion: Therefore, the CCI could be a promising scoring
system that could be used to identify risks in surgical patient
groups. © 2015 S. Karger AG, Basel
Introduction
An esophagectomy for cancer is associated with a high
postoperative mortality and morbidity. Mortality rates
have been reduced from approximately 16 to 3.2% over
the past years
[1–3] , and attention to the postoperative
complications has been increased. Quality of healthcare
cannot be assessed only by the occurrence of complica-
tions per se; the severity of these complications is also
more important. Complications after esophagectomy can
range from relatively small (e.g. urinary tract infection) to
severe complications (e.g. intensive care unit (ICU) ad-
mission after anastomotic leakage). In the past years, sev-
eral registry systems with accent on complication severity
have been developed to assess risks of surgical procedures
and to measure quality of care
[4–6] . The Clavien-Dindo
classification (CDC) is one method that is now widely
used by many surgical specialties to assess and compare
the severity of the postoperative complications
[5, 7–11] .
This severity classification grades the most severe compli-
cation that occurred in the admission period based on the
Key Words
Complication severity · Esophageal cancer · Surgery ·
Esophagectomy
Abstract
Background/Aims: Esophagectomies are associated with
high morbidity. To assess the complication severity, the Cla-
vien-Dindo classification (CDC) grades the most severe com-
plication. However, it ignores additional complications that
are equal or less severe. The comprehensive complication
index (CCI) incorporates all complication severities. It might
therefore be a better system to assess the severities. The aim
of this study was to validate the CCI compared to the CDC.
Methods: A prospective database was used to analyze 621
patients, who underwent an esophagectomy between 1993
and 2005. The CCI was calculated and the relation with tra-
ditional parameters was assessed and compared to the rela-
tion of the CDC with these parameters. Results: Complica-
tions occurred in 429 patients (69.1%). The correlation be-
tween the CCI and the CDC was r = 0.987, p < 0.01. The
relation of the CCI with 3 out of 7 parameters was not sig-
nificantly different compared to the relation of the CDC (p >
0.05). There was a significantly stronger relation (p < 0.05) of
the CCI with length of stay (LOS) (r = 0.663 vs. 0.646), a pro-
longed LOS (r = 0.542 vs. 0.530), reintervention, (r = 0.437 vs.
0.422) and reoperation rate (0.489 vs. 0.471) than the CDC.
Received: May 21, 2015
Accepted after revision: May 25, 2015
Published online: August 7, 2015
Mark I. van Berge Henegouwen, MD, PhD
Department of Surgery, Academic Medical Center
Meibergdreef 9
NL–1105 AZ Amsterdam (The Netherlands)
E-Mail m.i.vanbergehenegouwen
@ amc.uva.nl
© 2015 S. Karger AG, Basel
0253–4886/15/0325–0361$39.50/0
www.karger.com/dsu
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Dig Surg 2015;32:361–366
DOI: 10.1159/000433608
362
complication of treatment. However, it ignores all addi-
tional complications that are equal or less severe.
Hence, the comprehensive complication index (CCI) is
developed
[6] . This registry method incorporates the se-
verity of each complication that occurred after surgery. All
complications are scored separately according to the se-
verity classes of the CDC. The CCI can then be calculated
as the sum of all different severity classes by a formula that
is developed using an adopted operating-risk-index and
can be easily assessed by the CCI calculator available at the
website of AssessSurgery GmbH
[6, 12] . The CCI values
range from 0 to 100; a value of 0 reflects the absence of
complications, while a CCI of 100 indicates that the pa-
tient has died due to the occurrence of the complications.
A recently published study investigated the CCI between
the intervention versus control groups of 3 different ran-
domised controlled trials (RCTs). It showed that there was
a significant difference between the arms in 2 out of 3
RCTs (pancreas and esophageal resections) if the CCI was
used as a measure for complication severity, while there
was no difference in the number of the complications nor
the CDC between those arms
[13] . In the third RCT (colon
resections), the CCI confirmed the absence of the differ-
ence between the 2 arms. Based on the results of this study,
the CCI might be considered a useful and possibly a more
accurate method to assess risks in surgical procedures, but
it is still unknown if the CDC can completely be replaced
by the CCI in future studies. After all, while the CCI needs
a calculation, scoring only the worst complication can
more easily assess severity scores in patients by the CDC.
The aim of this study is, therefore, to investigate the accu-
racy of the CCI compared to the CDC. The relation of the
CCI with parameters such as (a prolonged) length of hos-
pital stay (LOS), (a prolonged) ICU-LOS, reintervention,
reoperation and reintubation rate was compared to the
CDC in a large patient cohort. If the CCI shows a stronger
relation with these parameters compared to the CDC, the
CCI could be a more valuable method to assess preopera-
tive and postoperative risks in esophageal cancer and to
use it postoperatively as a measure of quality of care.
Methods
Patients and Setting
The patient group that was analysed in this study was already
investigated in the O-POSSUM validation study
[14] . An existing
prospective database was used to perform the validation study,
which contained all patients who underwent a potentially curative
esophagectomy for an adenocarcinoma or squamous cell carci-
noma at the Department of Surgery of a tertiary referral university
hospital in Amsterdam, The Netherlands between January 1993
and August 2005. In this study, patients were excluded from the
analyses if they died due to the occurrence of complications, since
the CCI is then always 100 in spite of the severity of preceding
complications in these patients. Patients were also excluded if in-
formation on complication of treatment could not be obtained.
Data Collection
The CDC of the most severe complication, LOS (in days), a pro-
longed LOS (yes/no), ICU-LOS (in days), a prolonged ICU LOS
(yes/no), reintervention (yes/no), reoperation (yes/no) and reintu-
bation (yes/no) were already described in the existing database, and
were used for the analyses. A prolonged ICU-LOS was considered
the ICU-LOS higher than the median LOS. A reintervention was
defined as ‘a surgical, endoscopic or radiological intervention not
under general anesthesia as a treatment for the complications’
[5] .
All medical records were checked for additional complications.
A complication was defined as ‘an unintended and unwanted out-
come or state that occurred during or following medical care that
is so harmful to the patients’ health that it requires (adjustment of)
treatment or leads to permanent damage’
[15] . Complications
were registered if they occurred during hospital stay or if the pa-
tient was readmitted to the hospital within 30 days after surgery.
Each individual complication was further graded according to the
CDC. These grades were entered in the CCI-calculator to assess the
CCI values per patient
[12] . The values were used to calculate the
correlation coefficients.
The Relation between the CCI and the CDC with All
Parameters
A scatterplot was generated to assess the relation of the CCI
with LOS (in days) and ICU-LOS (in days) and to check the data
for outliers.
A Spearman’s rank test was used to calculate the correlation
coefficient of the CCI with (a prolonged) LOS, (a prolonged)
ICU-LOS, reintervention (e.g. radiologically guided drainage), re-
operation and reintubation rates. The correlation of the CDC with
(a prolonged) LOS, (a prolonged) ICU-LOS, reintubation, reop-
eration and reintervention was also calculated by the Spearman’s
rank test. Outcome values were expressed as the correlation coef-
ficient Rho (r
s
) and p values. A correlation coefficient of r
s
= 0.10–
0.29, r
s
= 0.30–0.49, and r
s
= 0.50–1.0 was considered a small, mod-
erate and strong correlation, respectively
[16] .
A Hotelling’s two-sample dependent test for correlations was
used to calculate the significant difference between the correlation
coefficient of the parameters with CDC and the CCI (in p values).
IBM SPSS Statistics version 22.0.0.0 (IBM, Armonk, N.Y.,
USA) was used for the calculation of the correlation coefficients.
The software ‘R Console version 2.15.0’ was used to perform the
Hotelling’s 2-sample dependent test for correlation. For all analy-
ses, p < 0.05 was considered to be statistically significant.
Results
Patients and Setting
The database contained 663 patients who underwent
an intentionally curative esophagectomy for an adeno-
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A Comparison of Two Severity Scoring
Systems
Dig Surg 2015;32:361–366
DOI: 10.1159/000433608
363
carcinoma or squamous cell carcinoma of the esophagus
proven by biopsy. Twenty-four patients (3.6%) were ex-
cluded from analysis because they died due to the occur-
rence of complications. For 18 patients (2.7%), treatment
of the complication(s) was not described in medical files,
or medical files were missing. Hence, a total of 621 pa-
tients were eligible for analysis ( table1 ).
All patients underwent an open esophageal resection.
The mean LOS was 23 days (range 8–143); the mean
ICU-LOS was 5 days (range 1–102). The mean LOS and
ICU-LOS were significantly different between patients
without complications versus patients with one or more
complications (14 vs. 26 days and 2 vs. 6 days, respective-
ly, both p < 0.001). The median LOS and ICU-LOS of the
total group was 16 and 2 days, respectively. A prolonged
LOS and ICU-LOS was therefore considered as LOS more
than 16 days (17 or longer) and as an ICU-LOS more than
2 days (3 days or longer), respectively.
There were 429 patients (69.1%) with one or more
complications. The median number of complications of
all patients was 1 (IQR 0–2) with a median CCI of 12.2
(IQR 0–33.7). The median number of complications of
the patients with complications was also 1 (IQR 1–2) with
a median CCI of 22.6 (IQR 8.7–43.3). A total of 829 indi-
vidual complications occurred in these patients ( table3 ).
Reintubation was required in 69/620 (11.1%) patients
after complications were noticed. There were 73/621 pa-
tients (11.8%) who underwent a reoperation and 71/619
patients (11.5%) who needed an intervention as the treat-
ment of one or more complication. It was not possible to
obtain the data of reintervention and reintubation for all
621 patients (n = 619 and 620, respectively).
Table2 shows the median CCI per CDC grade for 621
patients. It shows that a Clavien-Dindo grade II was cor-
related with CCI values rangingfrom 20.9 to 37.2 (with a
median CCI of 22.6) in this study. The maximum CCI
value in this Clavien-Dindo grade overlaps the lower CCI
in the Clavien-Dindo grade IIIa in this patient group
(with a median of 27.6, ranging from 26.2 to 50.0). The
table shows that the overlap of the values is also fitted in
other CDC grades.
The Relation between the CCI and the CDC with All
Parameters
A scatterplot suggested a positive curvilinear relation-
ship of the CCI with LOS and ICU-LOS. A correlation
coefficient of r
s
= 0.987 was found between the CCI and
the CDC (p < 0.01).
The correlation of both registry methods with (a pro-
longed) LOS, (a prolonged) ICU-LOS and reoperation
Table 1. Clinicopathological characteristics of 621 patients who
underwent elective esophagectomy
Patients characteristics n (%)
Median age, years (range) 64 (30–85)
Sex ratio (male:female) 475:146
Tumour type
Adenocarcinoma 431 (69.4)
Squamous cell carcinoma 181 (29.1)
Adenosquamous cell carcinoma 9 (1.4)
Neoadjuvant chemoradiotherapy
Yes 117 (18.8)
No 504 (81.2)
Preoperative stages*
0 11 (1.8)
I 54 (8.9)
IIa 187 (30.9)
IIb 44 (7.3)
III 293 (48.3)
IV 17 (2.8)
Operation
THE 400 (64.4)
TTE 221 (35.6)
Reconstruction
Gastric tube 602 (96.9)
Colon interposition 19 (3.1)
Anastomosis
Cervical 612 (98.6)
Intrathoracic 9 (1.4)
Postoperative stages**
I 79 (12.7)
IIa 129 (20.8)
IIb 51 (8.2)
III 248 (40.0)
IVa 113 (18.2)
THE = Transhiatal esophagectomy; TTE = transthoracic
esophagectomy.
*Data was missing for 15 patients. **Data was missing for 1
patient.
Table 2. The median CCI value compared to the CDC grade of 621
analysed patients who underwent an esophagectomy
CDC grades n (%) Median CCI (range)
0 192 (30.9) 0 (0)
I 120 (19.3) 8.7 (8.7–15.0)
II 133 (21.4) 22.6 (20.9–37.2)
IIIa 31 (5.0) 27.6 (26.2–50.0)
IIIb 34 (5.6) 39.7 (33.7–62.6)
IVa 96 (15.3) 48.1 (42.4–78.7)
IVb 15 (2.4) 69.9 (46.2–92.5)
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Dig Surg 2015;32:361–366
DOI: 10.1159/000433608
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was calculated for 621 patients. The correlation coeffi-
cient of reintervention and reintubation was calculated
for 619 and 620 patients, respectively.
A Spearman’s rank test showed a significant moderate
or strong correlation of the CCI and the CDC with all
parameters (p < 0.001). A strong correlation coefficient
was found between the CCI and LOS (r = 0.663), a pro-
longed LOS (r = 0.542), ICU-LOS (r = 0.514), and the
reintubation rate (r = 0.520). A moderate correlation co-
efficient was found between the CCI and a prolonged
ICU-LOS (r = 0.484), the reintervention (r = 0.437) and
reoperation rate (r = 0.489). The Clavien-Dindo score
also showed a strong correlation with LOS (r = 0.646),
ICU-LOS (r = 0.517), and reintubation rate (r = 0.520)
and showed a moderate relation with a prolonged LOS
(r= 0.530), a prolonged ICU-LOS (r = 0.486), reinterven-
tion (r = 0.422) and reoperation rate (r = 0.471). There
was a significantly stronger correlation between the CCI
and LOS (p < 0.001), a prolonged LOS (p = 0.028), rein-
tervention (p = 0.010) and reoperation rate (p = 0.001)
than between the Clavien-Dindo and these parameters.
The relations of the CCI with other parameters were not
significantly different compared to the CDC (p > 0.05;
table4 ).
Discussion
The CCI shows a moderate to strong relation with all
parameters (LOS, a prolonged LOS, ICU-LOS, a pro-
longed ICU-LOS, reintervention, reoperation and reintu-
bation rate). As compared to the relation of the CDC with
ICU-LOS, prolonged ICU-LOS, and reintubation, the re-
lation of the CCI with these variables is not significantly
different. However, 4 out of 7 parameters showed a sig-
nificantly higher correlation with the CCI than with the
CDC, that is, LOS, a prolonged LOS, reintervention and
reoperation.
This could be explained by the occurrence of multi-
ple complications among patients who are classified
into the same Clavien-Dindo grade. For example, there
were 2 patients with a CDC IIIb (reoperation). One pa-
Table 3. Type of complications (if ≥ 5) that occurred in patients (n)
who underwent an esophagectomy for an adeno- or squamous cell
carcinoma
Type of complication n (%)
Pneumonia 164 (19.9)
Vocal cord paralysis 71 (8.6)
Anastomotic or conduit leak or necrosis 63 (7.6)
Atrial fibrillation 56 (6.8)
Atelectasis 54 (6.5)
Pneumothorax 41 (5.0)
Chyle leak 34 (4.1)
Delirium 30 (3.6)
Urinary tract infection 28 (3.4)
Iatrogenic lesion arteria iliaca treated with
splenectomy 21 (2.5)
Postoperative bleeding 17 (2.1)
Wound dehiscence 16 (1.9)
Abscess 14 (1.7)
Ileus 14 (1.7)
Pleural effusion 13 (1.6)
Pulmonary embolism 12 (1.6)
Wound infection 12 (1.6)
Respiratory failure 10 (1.2)
Pleural empyema 9 (1.1)
Pseudomembranous colitis 9 (1.1)
Bladder retention 8 (0.9)
Diaphragmatic herniation 8 (0.9)
Sepsis 7 (0.8)
ARDS 6 (0.7)
Anastomotic stenosis 6 (0.7)
Pulmonary oedema 6 (0.7)
Clostridium difficile infection 6 (0.7)
Central line-associated bloodstream infection 5 (0.6)
Delayed gastric emptying 5 (0.6)
Other cardiac 20 (2.4)
Other gastro-intestinal 16 (1.9)
Other pulmonary 15 (1.8)
Other neurologic 10 (1.2)
Other 21 (2.5)
Total 826 (100)
Table 4. The correlation coefficients of the CCI and the CDC with
(a prolonged) hospital LOS (in days), (a prolonged) ICU-LOS (in
days), reintervention, reintubation (yes/no) and reoperation (yes/
no) of 621 patients, expressed as r
s
CCI (r
s
) CDC (r) Difference
(p value)
Hospital LOS 0.663 0.646 <0.001
Hospital LOS >16 days 0.542 0.530 0.028
ICU-LOS 0.514 0.517 0.589
ICU-LOS >2 days 0.484 0.486 0.724
Reintervention**
0.437 0.422 0.010
Reoperation 0.489 0.471 0.001
Reintubation*
0.520 0.520 1.000
* One missing value, the correlation was assessed for 620 pa-
tients. **Two missing values, the correlation was assessed for 619
patients.
All correlation coefficients (r
s
) were significant with a value of
p < 0.01.
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DOI: 10.1159/000433608
365
tient underwent a reoperation only after the occurrence
of a wound dehiscence (CCI 33.7, LOS 20 days), while
the other patient (CCI 62.6, LOS 143 days) suffered
from the following conditions: anastomotic leakage
drained at the bedside (grade I), pneumonia treated
with antibiotics (grade II), wound dehiscence treated
with reoperation (grade IIIb), underwent a second re-
operation indicated by ileus (grade IIIb), delirium treat-
ed with antipsychotic medicine (grade II), and an anas-
tomotic stenosis treated with endoscopic dilatation
(grade IIIa). The last patient shows an increase in both
the CCI as well as the LOS, but not in the Clavien- Dindo
grade.
Besides, in most CDC grades, the upper CCI per Cla-
vien-Dindo grade overlaps the lower CCI that correlates
with the following Clavien-Dindo grade. As shown in ta-
ble2 , the Clavien-Dindo grade IIIb is fitted with an upper
CCI that is higher than the lower CCI of the Clavien-Din-
do grade IVa. Apparently, a Clavien-Dindo grade IIIb
(reoperation) could be correlated with a more severe
postoperative course than a Clavien-Dindo grade IVa
(admission to the ICU for single organ failure) for pa-
tients with multiple complications who underwent a re-
operation. Therefore, we can conclude that the severity of
the complications does not depend only on the treatment
of the most severe complications.
Considering the stronger relation of the CCI with LOS,
a prolonged LOS, reintervention and reoperation rate
than the relation of the Clavien-Dindo classification with
these parameters, comparison of the severity of the post-
operative complications among patients is therefore more
accurate when the CCI is used. Since the relations of the
CCI and the CDC with the other parameters are equal, the
CCI can be used to assess differences in severity of com-
plications in other patients.
Another frequently used system to classify the sever-
ity of complications is the Accordion Severity Grading
System (ASGS)
[4] , which is a severity grading system
derived from the CDC. It contains a contracted classifi-
cation for smaller studies and an expanded classification
for larger studies, especially for complex procedures
such as esophageal resections. Compared to the CDC
grade IVa and IVb, which contains complications re-
quiring ICU admission due to single or multiple organ
failure, Accordion level 5 is based only on multiple or-
gan failure regardless of ICU admission. This is caused
by the fact that some patients require monitoring on the
ICU if moderate complications occur in the presence of
comorbidities. The development of the CCI incorpo-
rates the patients’ perspective and the severity of com-
plications is therefore more based on the impact that the
complications have on the patients instead of the sever-
ity of the complication itself. Second, the ASGS and oth-
er scoring systems derived from the CDC
[9, 17, 18] are
mostly ordinal scales that are less accurate to compare
patient groups in scientific studies than a quantitative
method.
The values of the CCI range from 0 to 100 and could
therefore be a more comparable registry method for re-
searchers instead of an ordinal value such as the CDC.
When complications cause death, however, a CCI value
of 100 does not reflect the severity of complications that
arise in the period before the moment of death. For
example, patients could die of a cerebral vascular accident
without any other accessory complication or they could
die after a period of accumulative complications eventu-
ally leading to multiorgan failure and death. The CCI
could possibly give more insight to the severity of com-
plications if the occurrence of complications in the period
before death would be separately incorporated in the
calculation. This is also supported by the development of
the postoperative morbidity index (PMI)
[19, 20] , anoth-
er quantitative severity scoring system derived from the
ASGS and the National Surgical Quality Improvement
Program, which showed that the value of death was not
always scored as 100 by 43 surgical experts using a scale
from 1 (minimal complication) to 100 (maximal compli-
cation). Unfortunately, the calculation of the PMI is
complex and it ignores the patients’ perspective in assess-
ing complication severity, whereas the incorporation of
the patients’ perspective by the CCI is a major change in
the use of a quantified complication severity scoring sys-
tem.
Since the O-POSSUM validation study, postoperative
morbidity has decreased, mostly attributable to the de-
crease in pulmonary complications
[21] . This could be
explained by the introduction of minimally invasive sur-
gery (which was not yet implemented in this patient
group) and improvement in postoperative care and en-
hanced recovery. In addition, neoadjuvant chemoradia-
tion is now standard care
[22] , whereas in this patient
cohort, only 18.8% of patients were treated with neoadju-
vant therapy. The results of this study must therefore be
carefully interpreted and applied to recent patient co-
horts. More research on a representative patient group
should therefore be performed. Besides, this study is
based on patients from a prospective database and the
treatment of complications was retrospectively collected.
As a consequence, 18 patients were excluded from the
analysis.
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In conclusion, the equal and stronger correlation of
the CCI with the traditional parameters in our study and
the results of the earlier study
[13] show that the CCI is a
more accurate registry method for complication severity
than the CDC. Although the fact that calculating CCI
scores is more complex and time consuming when com-
pared to the CDC, the CCI could be a valuable severity
scoring system to identify risks for the occurrence of
complications in patient groups in retrospective studies
and could be used to compare postoperative morbidity
more accurately than the CDC in future RCTs.
Disclosure Statement
S.M. Lagarde is supported by a Koningin Wilhelmina Fonds
(KWF, Dutch Cancer Society Fellowship, UVA 2013-5853).
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