ORIGINAL ARTICLES FROM THE ESA PROCEEDINGS
Waist Circumference and Waist/Hip Ratio Are Better Predictive
Risk Factors for Mortality and Morbidity after Colorectal Surgery
Than Body Mass Index and Body Surface Area
Alex H. Kartheuser, MD, PhD, MSc,∗ Daniel F. Leonard, MD,∗ Freddy Penninckx, MD, PhD,†
Hugh M. Paterson, MD, FRCSEd,∗ ‡ Dimitri Brandt, MD,∗ § Christophe Remue, MD,∗ Céline Bugli, PhD,¶
Eric Dozois, MD,|| Neil Mortensen, MD, PhD,∗∗ Frédéric Ris, MD,†† Emmanuel Tiret, MD, PhD,‡‡ and on behalf
of the Waist Circumference Study Group
From the ∗ Colorectal Surgery Unit and Colorectal Tumor Board, Cliniques Universitaires Saint-Luc, Brussels, Belgium; †Department of Abdominal Surgery,
Gasthuisberg University Hospital, Leuven, Belgium; ‡Department of Coloproctology, Western General Hospital, University of Edinburgh, Edinburgh,
United Kingdom; §Department of Digestive Surgery, Hôpital St-Joseph, Gilly,
Belgium; ¶Plateforme technologique de Support en Méthodologie et Calcul
Statistique, Université Catholique de Louvain, Louvain-La-Neuve, Belgium;
||Division of Colon and Rectal Surgery, Mayo Clinic, Rochester, MN, USA;
∗∗
Department of Colorectal Surgery, Oxford University Hospitals, Oxford,
United Kingdom; ††Service of Visceral Surgery, Geneva University Hospitals,
Geneva, Switzerland; and ‡‡Department of General and Digestive Surgery,
Hôpital St-Antoine, Paris, France.
Waist Circumference Study Group: N. Abbes Orabi (Centre Hospitalier Régional
de Mons, Mons, Belgium), S. Achkasov (State Research Centre of Coloproctology, Moscow, Russia), D. Aleshin (State Research Centre of Coloproctology, Moscow, Russia), P. Ambrosetti (Clinique Générale Beaulieu,
Geneva, Switzerland), J. Baulieux (CHU de Lyon, Hôpital de la Croix-Rousse,
Lyon, France), D. Brandt (Hôpital Saint-Joseph, Gilly, Belgium), F. Bretagnol
(Hôpital Beaujon, Clichy, France), P-Y. Bouteloup (Centre Hospitalier Privé
de Saint-Grégoire, Saint-Grégoire, France), R. Chamlou (Clinique Saint-Jean,
Bruxelles, Belgium), C. Coimbra (CHU du Sart-Tilman, Liège, Belgium), E.
Cotte (CHU de Lyon, Centre Hospitalier Lyon Sud, Pierre-Bénite, France), G.
Decker (Zithaklinik, Luxemburg, Grand Duchy of Luxemburg), A. D’Hoore
(KUL UZ Gasthuisberg, Leuven, Belgium), R. Droissart (Clinique Saint-Jean,
Bruxelles, Belgium), E. J. Dozois (Division of Colon and Rectal Surgery,
Mayo Clinic, Rochester, MN, USA), J. Etienne (Clinique Sainte-Elisabeth, Namur, Belgium), J-C. Etienne (Centre Hospitalier Inter-communal de Poissy,
Poissy, France), J-L. Faucheron (CHU de Grenoble–Hôpital A. Michallon,
La Tronche, France), P. Frileux (Hôpital Foch, Suresnes, France), O. Glehen (CHU de Lyon, Centre Hospitalier Lyon Sud, Pierre-Bénite, France), C.
Jehaes (Les Cliniques Saint-Joseph, Liège, Belgium), A.H. Kartheuser (Cliniques Universitaires Saint-Luc, Bruxelles, Belgium), Kayser J. (Zithaklinik,
Luxemburg, Grand Duchy of Luxemburg), Konrad B. (Geneva University
Hospitals, Geneva, Switzerland), Z. Krivokapic (Institute for Digestive Disease, Belgrade, Serbia), Ch. Laurent (Hôpital Saint-André, Bordeaux, France),
P-A. Lehur (Hôtel Dieu CHU de Nantes, Nantes, France), D. Leonard (Cliniques Universitaires Saint-Luc, Bruxelles, Belgium), J. Loriau (Groupe Hospitalier Saint-Joseph, Paris, France), J-Y. Mabrut (CHU de Lyon, Hôpital
de la Croix-Rousse, Lyon, France), B. Majerus (Clinique Saint-Pierre, Ottignies, Belgium), P. Matthiessen (Department of Surgery, Örebro University Hospital, Örebro, Sweden), Meurette G. (Hôtel Dieu CHU de Nantes,
Nantes, France), Michot F. (CHU Charles-Nicolle, Rouen, France), B. Monami (Les Cliniques Saint-Joseph, Liège, Belgium), N. Mortensen (John
Radcliffe Hospital, Oxford, United Kingdom), B. Navez (Hôpital SaintJoseph, Gilly, Belgium), Y. Panis (Hôpital Beaujon, Clichy, France), H. Paterson (Western General Hospital, Edinburgh, United Kingdom), F. Penninckx
(KUL UZ Gasthuisberg, Leuven, Belgium), J. Pfeifer (University Clinic of
Surgery, Graz, Austria), F. Pierard (Clinique Saint-Luc, Bouge, Belgium),
M. Pocard (Hôpital Lariboisière, Paris, France), C. Remue (Cliniques Universitaires Saint-Luc, Bruxelles, Belgium), F. Ris (Geneva University Hospitals), Geneva, Switzerland), Ph. Rouanet (CRLC Val d’Aurelle-Paul Lamarque, Montpellier, France), F. Rulli (University Hospital Roma, Roma, Italy),
E. Rullier (Hôpital Saint-André, Bordeaux, France), J-P. Saey (Centre Hospitalier Régional de Mons, Mons, Belgium), Y.A. Shelygin (State Research
Centre of Coloproctology, Moscow, Russia), C. Soravia (Clinique Générale
Beaulieu Geneva, Switzerland), L. Stainier (Clinique Saint-Pierre, Ottignies, Belgium), N. Tinton (Hôpital Saint-Joseph, Gilly, Belgium), E. Tiret
(Hôpital Saint-Antoine, Paris, France), Y. Parc (Hôpital Saint-Antoine, Paris,
722 | www.annalsofsurgery.com
Objectives: To determine whether body fat distribution, measured by waist
circumference (WC) and waist/hip ratio (WHR), is a better predictor of mortality and morbidity after colorectal surgery than body mass index (BMI) or
body surface area (BSA).
Background: Obesity measured by BMI is not a consistent risk factor for
postoperative mortality and morbidity after abdominal surgery. Studies in
metabolic and cardiovascular diseases have shown WC and WHR to be better
outcome predictors than BMI.
Methods: A prospective multicenter international study was conducted
among patients undergoing elective colorectal surgery. The WHR, BMI, and
BSA were derived from body weight, height, and waist and hip circumferences
measured preoperatively. Uni- and multivariate analyses were performed to
identify risk factors for postoperative outcomes.
Results: A total of 1349 patients (754 men) from 38 centers in 11 countries
were included. Increasing WHR significantly increased the risk of conversion
[odds ratio (OR) = 15.7, relative risk (RR) = 4.1], intraoperative complications (OR = 11.0, RR = 3.2), postoperative surgical complications (OR =
7.7, RR = 2.0), medical complications (OR = 13.2, RR = 2.5), anastomotic
leak (OR = 13.7, RR = 3.3), reoperations (OR = 13.3, RR = 2.9), and death
(OR = 653.1, RR = 21.8). Both BMI (OR = 39.5, RR = 1.1) and BSA
(OR = 4.9, RR = 3.1) were associated with an increased risk of abdominal
wound complication. In multivariate analysis, the WHR predicted intraoperative complications, conversion, medical complications, and reinterventions,
whereas BMI was a risk factor only for abdominal wall complications; BSA
did not reach significance for any outcome.
Conclusions: The WHR is predictive of adverse events after elective colorectal surgery. It should be used in routine clinical practice and in future
risk-estimating systems.
Keywords: body mass index, body surface area, colorectal surgery, morbimortality, waist/hip ratio
(Ann Surg 2013;258:722–730)
France), J-J. Tuech (CHU Charles-Nicolle, Rouen, France), A. Valverde (Centre
Hospitalier Victor Dupouy d’Argenteuil, Argenteuil, France), J. Van de Stadt
(Hôpital Erasme, Bruxelles, Belgium), B. Vinson-Bonnet (Centre Hospitalier
Intercommunal de Poissy, Poissy, France), Y. Van Molhem (Onze-Lieve-Vrouw
Ziekenhuis, Aalst, Belgium), and T. Yeung (John Radcliffe Hospital, Oxford,
United Kingdom).
Supported by grants from Fondation Saint-Luc, Clinique des Pathologies Tumorales
du Côlon et du Rectum, and Centre du Cancer, Cliniques Universitaires SaintLuc, Brussels, Belgium.
Disclosure: The authors declare no conflicts of interest.
Reprints: Alex H. Kartheuser, MD, PhD, MSc, Colorectal Surgery Unit, Cliniques
Universitaires Saint-Luc, Université Catholique de Louvain, 10 Avenue Hippocrate, B-1200 Brussels, Belgium; E-mail: [email protected].
C 2013 by Lippincott Williams & Wilkins
Copyright ISSN: 0003-4932/13/25805-0722
DOI: 10.1097/SLA.0b013e3182a6605a
Annals of Surgery r Volume 258, Number 5, November 2013
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Annals of Surgery r Volume 258, Number 5, November 2013
verweight [body mass index (BMI) = 25 to <30 kg/m2 ] and
obesity (BMI ≥30 kg/m2 ) are pandemic conditions. The most
recent data from the United States show that 40% of adult men and
30% of women fall within the overweight category. The prevalence
of obesity is increasing and significantly influences overall survival
of the general population.1 Although BMI, approximating body fat
percentage, has been the most popular measurement of obesity, recent
studies have promoted new measurements of obesity that reflect body
fat distribution.
The INTERHEART study found that abdominal obesity, defined by increased waist circumference (WC) and waist/hip ratio
(WHR), was predictive of risk of myocardial infarction whereas BMI
was not significantly associated.2,3 A further prospective study identified WHR as a better predictor of death after myocardial infarction
than BMI.4
Both WC and hip circumference (HC) and their ratio and body
surface area (BSA) are the most frequently cited alternatives to BMI.
In a large sample of the European population, both general adiposity,
measured by BMI, and abdominal adiposity, expressed by WC and
WHR, were found to be associated with increased death rate. Therefore, the combined use of these indicators in assessing the risk of
death was advocated.5
Although many surgeons suspect that obesity negatively influences outcomes after abdominal surgery, well-designed studies have
been unable to show that obesity is an independent risk factor for major morbidity or mortality after general abdominal surgery.6–8 Studies
specific to colorectal surgery have confirmed these observations.9–11
However, these studies may have used an inappropriate measure of
obesity. Indeed, abdominal obesity, measured by WC and WHR, may
be a better predictor of adverse outcome after abdominal surgery than
BMI. Therefore, the aim of our study was to answer the following
question: Are WC and WHR better predictive risk factors than BMI
or BSA to assess the impact of obesity on mortality and morbidity
after colorectal surgery?
O
Waist/Hip Ratio and Colorectal Surgery
classification was used: underweight (BMI <18.5), normal weight
(BMI 18.5 to <25), overweight (BMI 25 to <30), obesity (BMI
≥30), including obesity classes I (30 to <35), II (35 to <40), and III
(≥40).12
WC was measured with the patient standing during end expiration, with unclothed abdomen at the midpoint between the lower
costal margin and the top of the iliac crest with a horizontal tape
measure and without compression of the skin (Fig. 1). The Lean classification was used: normal (<94 cm in men and <80 cm in women),
low risk (94–102 cm in men and 80–88 cm in women), and high risk
(>102 cm in men and >88 cm in women).13 HC was measured with
the patient standing lightly clothed, measured with a horizontal tape
measure at the largest circumference over the buttocks.
To ensure proper measurements of WC and HC, written guidelines explaining the correct way to proceed step by step were sent to
all local investigators. Measurements were recorded in duplicate to
the nearest 0.5 cm. If the difference between the 2 measurements was
greater than 2 cm, a third measurement was taken and the mean of the
2 closest measurements was recorded. Although, ideally, the measurements should be taken independently by 2 observers, in fact, there
are data showing that these measurements are highly reproducible
(r >0.99) and that measurement by a single observer is acceptable.14
The WHR was calculated according to the following formula:
WC (cm)/HC (cm). Thresholds for WHR of 1.0 in men and 0.85 in
women were used to define abdominal obesity.15 BSA (in m2 ) was
calculated according to the Dubois formula: 0.007184 × Weight0.425
× Height0.725 .16
Outcome Measures
The main outcome measures were in-hospital mortality, intraoperative complications and conversion from laparoscopy to open
surgery, and in-hospital postoperative medical and surgical morbidity, with particular emphasis on anastomotic leak (for procedures including an anastomosis), reoperation, and abdominal wall
PATIENTS AND METHODS
A prospective multicenter international study was conducted
involving 38 colorectal surgery units from 11 countries. Patients undergoing elective colorectal resection by either open approach or laparoscopic approach for colorectal cancer, polyps, polyposis, volvulus, and diverticular disease were included during the period from
November 2008 to December 2009. Exclusion criteria were as follows: patient age less than 18 years, inability to give informed consent,
emergency surgery, pregnancy, and comorbidity resulting in altered
abdominal circumference measurement (ascites secondary to chronic
liver disease, peritoneal carcinomatosis, intestinal obstruction, abdominal mass lesions >20 cm of diameter on computed tomographic
scan, preexisting abdominal stoma, incisional hernia). Patients with
inflammatory bowel disease were also excluded because this group
carries an increased risk of adverse outcomes such as venous thromboembolism.
Height, weight, WC, and HC were recorded for each patient in
addition to routine patient demographic data regarding comorbidities,
diagnosis, operative data, and postoperative morbidity and mortality.
Data were stored in a database designed for this study with online/offline data submission for each participating center. The central
database was managed by an independent data management center
(Data Management System S.A., Brussels, Belgium) and reviewed
regularly for inconsistencies and missing data. Centers were contacted by e-mail or phone when such problems were detected.
Measurement of Anthropometric Parameters
BMI was calculated as weight in kilograms divided by height in
meters squared. The World Health Organization terminology for BMI
C 2013 Lippincott Williams & Wilkins
FIGURE 1. A measuring tape is placed around the trunk, at a
point midway between the lower costal margin and the iliac
crest, while the patient is standing. WC is recorded to the nearest 0.5 cm at the end of a normal expiration. HC is measured
at the widest point over the greater trochanters.
www.annalsofsurgery.com | 723
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Annals of Surgery r Volume 258, Number 5, November 2013
Kartheuser et al
complications. In this study, the term “abdominal wall complications”
refers to surgical site infection (SSI), that is, infection of the superficial or deep tissues of the surgical incision, in addition to superficial
wound dehiscence and evisceration.
Statistical Analysis
The likelihood ratio test (and the Fisher exact test, where appropriate) was used to assess the statistical significance of an association between BMI, WC, WHR, BSA, and the outcome measures.
Predictions for the risk of complication were analyzed using logistic
regression models, adjusted for the 4 anthropometric markers. Corresponding relative risk (RR) and odds ratio (OR) were reported. The
results of univariate analysis were used to identify candidate variables
to create stepwise backward multivariate logistic regression models.
Area under the curve and generalized R2 statistics were used to assess performance of the models. When not otherwise specified, the
anthropometric variables were tested as continuous variables.
All P values were 2-tailed, and P values of less than 0.05
were considered statistically significant. Analysis was performed using JMP software (version 10) and SAS software (version 9.3; SAS
Institute Inc, Cary, NC).
Ethical Committee Approval
This study was conducted in conformity with the Declaration of Helsinki (Ethical Principles for Medical Research Involving
Human Subjects, Tokyo, 2004). The study protocol was approved by
the Ethical Committee of the Cliniques Universitaires St-Luc, Brussels, Belgium (reference #B40320084561) for all Belgian centers.
Centers outside Belgium obtained local ethical committee approval
individually. Informed consent was obtained from each patient. An
information leaflet was provided.
Study Registration
This clinical trial has been registered in the ClinicalTrials.gov
online database: registration number NCT01737515.
RESULTS
Patient- and Surgery-Related Characteristics
A total of 1349 patients (mean age: 64.8 years ± 13.2; 754
men), from 38 centers in 11 countries, who underwent elective colorectal surgery were included in this prospective multicenter study.
Patient demographics and diagnostic and operative characteristics
are shown in Table 1. According to International Diabetes Federation
definitions, 687 patients (50.9%) had metabolic syndrome.17 The majority of patients (n = 978; 72.5%) were operated on for colorectal
cancer [colon (n = 559; 57.2%); rectum (n = 419; 42.8%)]. Patients
included in the present study underwent a wide range of colorectal
surgical procedures, with a laparoscopic approach used in 56.4%.
Only 150 patients (11%) were enrolled in an enhanced recovery program.
Anthropometric data are given in Table 2. More than half of
the patients (54.6%) were overweight (ie, BMI >25). In 645 patients
(47.1%), WC exceeded the threshold for at-risk obesity (men: >102
cm; women: > 88 cm) and 730 patients (54.1%) had a high-risk WHR
(men: >1.0; women: >0.88).
TABLE 1. Patient and Operative Characteristics
Variable Category
n (%)
Patients
Age, yr
Mean (SD)
Median (range)
Sex
Male
Female
Comorbidity
Cirrhosis
COPD
Diabetes
Type 1
Type 2
Metabolic syndrome∗
Ischemic heart disease
Neurological disorders
Pulmonary embolism
Smoker
Weight loss >10% in 6 mo
ASA score
I
II
III
IV
Unknown
Diagnosis
Cancer
Colon
Rectal
Diverticulitis
Other
Previous abdominal surgery
Bowel preparation
Surgical approach
Open (laparotomy)
Laparoscopic
Surgical procedures
Right colectomy
Left colectomy
Partial mesorectal excision
Total mesorectal excision
Total colectomy
Hartmann procedure
Abdominoperineal excision
Proctocolectomy
Other
Construction of anastomosis
End stoma
Diverting stoma if anastomosis
Colostomy
Ileostomy
Extended “en bloc” resection
Abdominal drainage
Enhanced recovery after surgery
1349
64.8 (13.2)
65.6 (18.0–100.0)
754 (55.9)
595 (44.1)
419 (31.1)
13 (1.0)
137 (10.2)
151 (11.2)
12 (1.0)
136 (10.1)
687 (50.9)
175 (13.0)
77 (6.0)
32 (2.4)
446 (33.1)
98 (7.3)
260 (19.3)
767 (56.8)
303 (22.5)
14 (1.0)
5 (0.4)
978 (72.5)
559 (57.2)
419 (42.8)
266 (19.7)
105 (7.8)
575 (42.6)
536 (39.7)
588 (43.6)
761 (56.4)
277 (20.5)
543 (40.3)
103 (7.6)
269 (19.9)
34 (2.5)
19 (1.4)
71 (5.3)
11 (0.8)
22 (1.6)
1231 (91.3)
118 (8.7)
306 (22.7)
59/306 (19.3)
247/306 (80.7)
139 (10.3)
657 (48.7)
150 (11.0)
∗
According to International Diabetes Federation definition.17
ASA indicates American Society of Anesthesiology Score; COPD, chronic
obstructive pulmonary disease.
Mortality and Morbidity
Operative Data
Intra- and postoperative data are summarized in Table 3. A
majority of patients (56.4%) underwent laparoscopic surgery, with a
conversion rate of 12.7%. Intraoperative adverse events occurred in
204 patients (15.1%).
724 | www.annalsofsurgery.com
Nine patients died (global mortality 0.7%). A total of 178
patients (13.2%) developed a medical complication, and 240 patients
(17.7%) had a surgical complication.
Reoperation, defined as an emergency reintervention performed during the same admission period, was undertaken in 86
C 2013 Lippincott Williams & Wilkins
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Annals of Surgery r Volume 258, Number 5, November 2013
TABLE 2. Anthropometric Data
TABLE 3. Intra- and Postoperative Features
Variable Category
Patients
Weight, kg
Mean (SD)
Median (range)
Height, cm
Mean (SD)
Median (range)
BMI
Mean (SD)
Median (range)
BMI classification
<18.5
18.5 to <25
25 to <30
30 to <35
35 to <40
≥40
WC, cm
Mean (SD)
Median (range)
WC classification for men, cm
<94
94–102
>102
WC classification for women, cm
<80
80–88
>88
HC, cm
Mean (SD)
Median (range)
WHR
Mean (SD)
Median (range)
WHR classifications for men
<0.9
0.9–1.0
>1.0
WHR classifications for women
<0.8
0.8–0.88
>0.88
BSA, m2
Mean (SD)
Median (range)
Waist/Hip Ratio and Colorectal Surgery
n (%)
1349
74.5 (16.1)
73.0 (36.0–150.0)
168.4 (9.3)
169.0 (147.0–201.0)
26.2 (4.8)
25.6 (50.1–13.7)
38 (2.8)
573 (42.5)
487 (36.1)
178 (13.2)
60 (4.4)
13 (1.0)
90.0 (14.7)
96.0 (53.0–181.0)
227 (30.1)
225 (29.8)
302 (40.1)
137 (23.0)
115 (19.3)
343 (57.7)
99.6 (12.0)
99.0 [40.0–167.0]
0.97 (0.14)
0.96 [0.49–2.42]
65 (8.6)
332 (44.0)
357 (47.4)
75 (12.6)
147 (24.7)
373 (62.7)
1.85 (0.22)
1.85 (1.29–2.63)
Variable Category
n (%)
Mortality
Global morbidity
Medical complications
Stroke
Deep venous thrombosis
ICU admission
Myocardial infarction
Pneumonia
Pulmonary embolism
Urinary tract infection
Pleural effusion
Cardiac failure
Other
Converted laparoscopic approach
Conversion causes
Adhesions
Bleeding
Visceral injury
Obesity
T4 tumors
Other
Intraoperative complications
Blood transfusion
Bowel perforation
Tumor perforation
Conversion∗
Severity of complications†
1–2
3
4
5
Postoperative surgical complications
Colonic ischemia
Hemorrhage requiring transfusion
Intestinal obstruction
Ileus
Intra-abdominal abscess
Peritonitis
Anastomotic leak
Other
Reoperation (emergent)
Abdominal wall complications
Wound dehiscence
Wound abscess
Evisceration
9 (0.7)
355 (26.3)
178 (13.2)
4 (0.3)
4 (0.3)
39 (2.9)
4 (0.3)
17 (1.3)
10 (0.7)
51 (3.8)
18 (1.3)
9 (0.7)
95 (7.0)
97 (12.7)
97/761 (12.7)
35/97 (36.1)
5/97 (5.2)
3/97 (3.1)
19/97 (19.6)
11/97 (11.3)
24/97 (24.7)
204 (15.1)
85 (6.3)
12 (0.9)
23 (1.7)
97/761 (12.7)
256 (19.0)
59 (4.5)
31 (2.3)
9 (0.7)
240 (17.8)
6 (0.4)
13 (1.0)
13 (1.0)
69 (5.1)
19 (1.4)
12 (0.9)
78/1231 (6.3)‡
4 (0.3)
86 (6.4)
67 (5.0)
17 (1.3)
55 (4.1)
3 (0.2)
∗
Applies only for the laparoscopic cases.
†According to the Dindo-Clavien classification.
‡Applies only for patients with an anastomosis (stomas excluded).
patients (6.4%), and 67 patients (5.0%) experienced an abdominal
wall complication including SSI (Table 3).
Using univariate analysis with 46 variables tested, 17 were potential risk factors for intraoperative complications, 6 for conversion,
19 for global morbidity, 17 for medical complications, 13 for surgical
complications, 6 for anastomotic leak, 4 for repeat surgery, and 14
for abdominal wall surgery (Table 4).
There was a significant relationship between WHR and all 9
outcomes, with an RR of 1.8 (1.2–2.8) for overall morbidity and an
RR of 3.2 (1.8–5.9) for intraoperative complications. ORs ranged
from 7.7 for surgical postoperative complications to 15.7 for the
conversion rate in laparoscopic surgery (Table 5). In contrast, both
BMI and BSA were found to be associated only with abdominal wall
complications.
After stepwise backward multivariate logistic regression, 12
variables were retained as risk factors for 1 or more intra- or postoperative outcomes (Table 6). Although WHR was significantly associated
C 2013 Lippincott Williams & Wilkins
with mortality in the univariate analysis, this outcome was excluded
from the multivariate analysis because of the low number of events
(n = 9; 0.7%). The most frequently involved variables were male
sex, increased WHR, perioperative blood transfusion, and abdominal
drainage.
A special focus on the anthropometric risk factors related to
obesity resulted in WHR as an independent risk factor for intraoperative complications, conversion from a laparoscopic approach to
an open approach, medical complications, and reoperation. Both WC
and BMI were predictors for surgical postoperative complications and
abdominal wall complications, respectively. BMI had some protective effect on medical complications, whereas BSA had a protective
effect on the occurrence of postoperative complications.
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Annals of Surgery r Volume 258, Number 5, November 2013
Kartheuser et al
TABLE 4. Univariate Analysis of the Risk Factors for Intra- and Postoperative Outcomes
Postoperative Outcome
Intraoperative Outcome
Variable Category
Age
Sex (male)
Comorbidity
No. comorbidities
Cirrhosis
COPD
Diabetes
Type 1
Type 2
Metabolic syndrome∗
Ischemic heart disease
Neurological disorders
Pulmonary embolism
Smoker
Weight loss >10%
ASA score
Pathology
Cancer
Tumor location
Diverticulitis
Volvulus
Other
Weight
BMI†
BMI classification
WC,† cm
WC classification
WHR†
WHR classification
BSA†
Previous abdominal
surgery
Bowel preparation
Surgical approach‡
Surgical procedures
Anastomosis
Diverting stoma
En bloc resection
No. organs
Blood transfusion
No. blood transfusions
Abdominal drainage
ERAS
Complications
Conversion
P < 0.02
P < 0.01
P = 0.002
P < 0.001
P < 0.02
P < 0.0001
P < 0.02
P < 0.005
P < 0.05
Mortality
All
Medical
Complications Complications
P < 0.001
P < 0.01
P = 0.0002
P < 0.0001
P < 0.002
P < 0.0001
P < 0.05
P < 0.02
P < 0.02
P < 0.005
Surgical
Complications
P < 0.0001
P < 0.0001
P < 0.0001
P < 0.02
P < 0.05
P < 0.0001
P = 0.001
Anastomotic
Leak
Reoperation
Abdominal Wall
Complications
P < 0.05
P < 0.02
P < 0.05
P = 0.001
P < 0.05
P < 0.05
P < 0.05
P < 0.0001
P < 0.002
P < 0.05
P < 0.0001
P < 0.02
P < 0.002
P < 0.02
P < 0.005
P < 0.01
P < 0.01
P < 0.05
P < 0.02
P < 0.005
P < 0.002
P < 0.01
P < 0.01
P < 0.002
P < 0.0001
P < 0.0005
P < 0.05
P < 0.02
P < 0.0001
P < 0.005
P < 0.001
P < 0.002
P < 0.001
P < 0.0001
P < 0.001
P < 0.001
P < 0.02
P < 0.0001
P < 0.02
P < 0.01
P < 0.005
P < 0.01
P < 0.0001
P < 0.05
P < 0.05
P < 0.05
P < 0.05
P <0.05
P < 0.05
P < 0.05
P < 0.0001
P < 0.0001
P < 0.002
P < 0.005
P < 0.01
P < 0.05
P < 0.02
P < 0.05
P < 0.002
P < 0.0002
P < 0.0005
P < 0.002
P < 0.0001
P < 0.02
P < 0.05
P < 0.05
P = 0.0001
P < 0.01
P < 0.0005
P < 0.005
P < 0.02
∗
According to the International Diabetes Federation definition.17
†Anthropometric measures have been tested as continuous variables.
‡Surgical approach: laparotomy versus laparoscopy (including conversion).
ASA indicates American Society of Anesthesiology; COPD, chronic obstructive pulmonary disease; ERAS indicates enhanced recovery after surgery.
DISCUSSION
This prospective, multicenter, international study of patients
who underwent colorectal surgery shows that WHR is superior to BMI
or WC in predicting important surgical outcomes, including intraoperative complications, conversion from the laparoscopic approach to
the open approach, medical complications, and reoperation.
Thus, the previous failure to prove the long-held suspicion of
many surgeons that obesity carries an increased risk of adverse outcomes may be explained simply: previous studies used inappropriate
measurement of obesity. To our knowledge, this is the first study to examine the impact of abdominal (central) obesity, as defined by WHR
and WC, on outcomes of abdominal surgery. Hence, there is little surgical literature with which to compare our results. Previous studies
have shown an association between BMI and wound complications,
an observation supported by this study.7,18,19
One might expect increased postoperative morbidity in obese
patients because they often have the worse American Society of Anesthesiology score or more preexisting comorbid illnesses, including
726 | www.annalsofsurgery.com
diabetes, hypertension, cardiovascular disease, and lipid disorder.20
Moreover, obesity might increase technical difficulty and thus operative time in laparoscopic surgery.18 However, almost all previous
studies examining the impact of obesity on conversion from a laparoscopic approach to an open approach and postoperative morbidity
and mortality have used BMI-based definitions, and, in most studies,
no association could be observed.6–10,20,21
Although BMI was found to be 1 of the 3 most important
factors influencing postoperative outcome after colorectal surgery in
a large series of 3552 patients, BMI-defined obesity has not been
consistently featured as an independent predictor of risk in any large
prospective analysis.22–27 The data in this study are robust: All centers
in this study specialize in colorectal surgery, which is reflected by the
low mortality rate of 0.7% and the overall morbidity rate of 26.2% in
accordance with the 24.3% rate published by Cohen et al26 in a data
set of 28,863 colorectal procedures.
In our univariate logistic regression model, the WHR showed
an RR of 3.3 for mortality. However, it had to be excluded as a
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C 2013 Lippincott Williams & Wilkins
4.5
31.4
1.1 [1.00–1.01]
1.03 [1.00–1.04]
OR
6.7
10.2
WC
1.01 [1.01–1.02]
1.01 [1.003–1.03]
RR [CL]
<0.001
<0.01
<0.05
<0.01
P
8.3
13.2
7.7
13.7
13.3
12.3
653.1
11.0
15.7
OR
WHR
1.8 [1.2–2.8]
2.5 [1.3–4.6]
2.0 [1.1–3.5]
3.3 [1.2–9.2]
2.9 [1.0–8.0]
3.3 [1.002–10.6]
21.8 [5.5–86.3]
3.2 [1.8–5.9]
4.1 [2.0–8.4]
RR [CL]
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
4.36 (2.20)
0.35 (0.17)
Estimate,
Mean (SD)
4.88 (2.22)
0.52 (0.16)
<0.005
<0.05
Estimate,
Mean (SD)
P
P
<0.05
<0.001
Conversion
The 4 anthropometric variables have been tested as continuous variables.
ERAS indicates enhanced recovery after surgery.
Sex
No. comorbidities
WC
WHR
BMI
BSA
Bowel preparation
Anastomosis construction
“En bloc” resection
Blood transfusion
Abdominal drain
ERAS
Variable Category
Complications
Intraoperative Outcome
P
<0.002
0.41 (0.13) <0.002
0.22 (0.07) <0.002
0.21 (0.09) <0.002
− 0.85 (0.3)
0.31 (0.08) <0.0001
0.36 (0.08) <0.0001
Estimate,
Mean (SD)
All Complications
P
0.38 (0.15) <0.01
1.11 (0.53) <0.05
− 0.05 (0.02) <0.005
P
39.5
<0.01
<0.05
<0.005
<0.005
1.26 (0.57)
0.42 (0.14)
0.37 (0.11)
<0.05
0.0001
P
0.21 (0.08)
0.02 (0.01)
0.31 (0.09)
Estimate,
Mean (SD)
OR
BMI
0.62 (0.16)
0.26 (0.13)
Estimate,
Mean (SD)
<0.0001
<0.05
P
P
0.61 (0.17)
1.49 (0.64)
Estimate,
Mean (SD)
0.0003
<0.02
P
<0.05
P
0.52 (0.21)
0.64 (0.18)
0.46 (0.19)
0.13 (0.03)
<0.01
<0.001
<0.01
<0.0001
P
Abdominal wall
Complications
4.9
OR
BSA
Estimate,
Mean (SD)
3.1 [1.1–8.6]
RR [CL]
Reoperation
< 0.0001
Anastomotic Leak
Postoperative Outcome
1.1 [1.05–1.14]
RR [CL]
Surgical
Complications
<0.002
<0.001
<0.01
<0.01
<0.01
<0.05
<0.0001
<0.002
<0.005
0.49 (0.11) <0.0001
Estimate,
Mean (SD)
Medical
Complications
TABLE 6. Multivariate Analysis of the Risk Factors for Intra- and Postoperative Outcomes
Anthropometric measures have been tested as continuous variables.
CL indicates confidence limits; OR, odds ratio.
Intraoperative features
Complications
Conversion
Postoperative outcome
All complications
Medical complications
Surgical complications
Anastomotic leak
Reoperation
Abdominal wall complications
Mortality
Outcome Variable Category
TABLE 5. Results of Univariate Analysis: RR and OR of the Effects of WC (cm), WHR, BMI (kg/m2 ), and BSA (m2 ) on Intra- and Postoperative Outcomes
Annals of Surgery r Volume 258, Number 5, November 2013
Waist/Hip Ratio and Colorectal Surgery
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Kartheuser et al
potential candidate from the multivariate analysis because of the very
low number of deaths (n = 9; 0.7%). In that respect, the present study
needs to be confirmed in a larger cohort of patients.
Regarding laparoscopic surgery, the rate of conversion reported
in the literature ranges widely from 11% to 39%.21 Data from the UK
CLASICC (Conventional versus Laparoscopic-Assisted Surgery In
Colorectal Cancer) trial found that BMI was an independent risk
factor for conversion to open surgery in rectal and colon cancer
resection,28 whereas the Cleveland Clinic has reported increased conversion rates and morbidity among obese patients undergoing laparoscopic colectomy.29,30 In a recent meta-analysis, the conversion rate
varied from 1.1% to 18.0% in nonobese patients and from 0% to
45.8% in obese patients.20 The common reasons for conversion were
exposure problems and dissection difficulties. In a comparative study
between obese and nonobese patients, Pikarsky et al31 have shown
that the reason for conversion in the obese group was more likely to
be poor visualization secondary to intra-abdominal fat or bleeding
whereas the most likely reason for conversion in the nonobese group
was adhesions. Because WHR is a more specific indicator for visceral intra-abdominal fat, it was expected to be a strong risk factor
for conversion. In the present study, the WHR had an RR of 4.1, an
OR of 15.7 in the univariate logistic regression model, and a high
significance in the multivariate model for conversion.
As far as reoperations are concerned, among 9 comparative
studies, only one reported a significantly increased reoperation rate
in obese patients after laparoscopic surgery, whereas authors of other
studies observed no statistically significant difference in the overall reoperation rate between obese (0%–18.2%) and nonobese (0%–8.6%)
patients.20 Again, in the present study, an increased WHR was related
to an increased risk of reoperation (OR = 13.3, RR = 2.9) in univariate analysis, remaining statistically significant after multivariate
logistic regression.
Obesity, defined by BMI, has been validated as a risk factor
for SSIs, with some reports demonstrating an increased risk of SSI
as high as 60% among obese patients.7,19,20,32,33 WC is thought to
reflect abdominal adiposity, including subcutaneous fat layer, and
intra-abdominal visceral adiposity. Therefore, it was expected to be
a risk factor for both surgical complications and abdominal wall
complications, including wound infection. However, although using
WC, the OR was 31.4 and RR was 1.01 for SSI in univariate logistic
regression analysis, it did not reach statistical significance in the
multivariate model. Why WC does not seem to be a risk factor for
SSI in this study remains unclear and requires further large-scale
studies.
In our study, increasing BSA seemed to favorably influence the
rate of complications for unknown reasons. This contrasts with the
findings of Vaccaro et al,34 who in a series of 916 consecutive patients,
showed that BSA of 1.8 m2 or more led to a higher conversion rate
and operative time.
Besides anthropometric factors, male sex, abdominal drainage,
and blood transfusion were independent predictors for a number
of main outcomes in the multivariate analysis. Two systematic reviews of abdominal drainage have shown no evidence of benefit
on mortality, anastomotic leakage, wound infection, or other major
complications.35,36 However, the conclusions were based on methodologically poor studies and should be interpreted with caution. In
the present study, at least 27.5% of anastomoses were rectal. This
percentage differs from the ones reported in systematic reviews. This
difference might explain the observed significant prognostic value of
drainage.
Conversely, our findings concerning blood transfusion support
published data.37,38 The predictive value of male sex for morbidity
and, more specifically, for anastomotic leakage in our study confirms
previous results based on a very large series. Possible explanations
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Annals of Surgery r Volume 258, Number 5, November 2013
for these findings include the difficulty of achieving satisfactory
anastomosis within the narrow male pelvis in restorative rectal
resection.39,40
In the future, our data about WC and WHR have to be compared
with other modalities currently proposed to measure fat. Indirect
measurement can be done through dual-energy x-ray absorptiometry,
ultrasonography, and bioelectric impedance. Direct measurement may
include computed tomography and magnetic resonance imaging. An
ideal measurement method should be noninvasive with no or limited
radiation exposure, reliable with low variability, suitable for all body
sizes, broad in availability, and time- and cost-effective.41
CONCLUSIONS
This study demonstrates the usefulness of WHR in predicting
intraoperative adverse events, conversion from laparoscopic to open
surgery, medical postoperative complications, and the need for reoperation after colorectal surgery. WC may also be useful for predicting
postoperative surgical complications. In contrast, BMI is of limited
use, predicting only abdominal wall complications.
These findings will need to be confirmed using a large series of
data from various institutions. A validation study of the present results
is currently under way with the objectives of finding cutoff values of
WC and WHR not only for morbidity but also for mortality after
colorectal surgery. In conclusion, the use of WC and WHR should be
further explored for better risk estimation in clinical practice.
ACKNOWLEDGMENTS
The authors thank the Fondation Saint-Luc and Mr Peterbroeck, the Centre du Cancer, and the Colorectal Tumor Board of
St-Luc University Hospital, Brussels, for their support. The authors
also thank Mr P. Mailleux for data management and Mrs Nadine
Thiebaut, Mrs Nathalie Vieren, and Mrs Joëlle Caudron for typewriting and layout of the manuscript.
REFERENCES
1. Flegal KM. Association of all-cause mortality with overweight and obesity
using standard body mass index categories: a systematic review and metaanalysis. JAMA. 2013;309:71–82.
2. Yusuf S, Hawken S, Ôunpuu S, et al. Effect of potentially modifiable risk factors associated with myocardial infarction in 52 countries (the INTERHEART
study): case-control study. Lancet 2004;364:937–952.
3. Yusuf S, Hawken S, Ôunpuu S, et al. Obesity and the risk of myocardial infarction in 27,000 participants from 52 countries: a case-control study. Lancet.
2005;366:1640–1649.
4. Kragelund C, Hassager C, Hildebrandt P, et al. Impact of obesity on long-term
prognosis following acute myocardial infarction. Int J Cardiol 2005;98:123–
131.
5. Pischon T, Boeing H, Hoffmann K, et al. General and abdominal adiposity and
risk of death in Europe. N Engl J Med. 2008;359:2105–2120.
6. Davenport DL, Ferraris VA, Hosokawa P, et al. Multivariable predictors of
postoperative cardiac adverse events after general and vascular surgery: results from the patient safety in surgery study. J Am Coll Surg. 2007;204:
1199–1210.
7. Dindo D, Muller M, Weber M, et al. Obesity in general elective surgery. Lancet.
2003;361:2032–2035.
8. Herrera FA, Yanagawa J, Johnson A, et al. the Prevalence of obesity and postoperative complications in a Veterans Affairs Medical Center general surgery
population. Am Surg. 2007;73:1009–1012.
9. Laurent C, Leblanc F, Gineste C, et al. Laparoscopic approach in surgical
treatment of rectal cancer. Br J Surg. 2007;94:1555–1561.
10. Leroy J, Ananian P, Rubino F, et al. The impact of obesity on technical
feasibility and postoperative outcomes of laparoscopic left colectomy. Ann
Surg. 2005;241:69–76.
11. Tekkis PP, Prytherch DR, Kocher HM, et al. Development of a dedicated riskadjustment scoring system for colorectal surgery (colorectal POSSUM). Br J
Surg. 2004;91:1174–1182.
C 2013 Lippincott Williams & Wilkins
Copyright © 2013 Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
Annals of Surgery r Volume 258, Number 5, November 2013
12. World Health Organization. BMI classification [WHO Global Database on
Body Mass Index]. March 3, 2013. Available at: http://apps.who.int/bmi/index.
jsp?introPage=intro 3.html. Accessed March 9, 2013.
13. Lean MEJ, Han TS, Morrison CE. Waist circumference as a measure for
indicating need for weight management. BMJ. 1995;311:158–161.
14. Wang J, Thornton JC, Bari S, et al. Comparisons of waist circumferences
measured at 4 sites. Am J Clin Nutr. 2003;77:379–384.
15. Executive summary of the clinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults. Arch Intern Med.
1998;158:1855–1867.
16. Dubois D, Dubois EF. A formula to estimate the approximate surface area if
height and weight be known. Arch Intern Med. 1916;17:863–871.
17. Johnson LW, Weinstock RS. The metabolic syndrome: concepts and controversy. Mayo Clin Proc. 2006;81:1615–1620.
18. Balentine CJ, Wilks J, Robinson C, et al. Obesity increases wound complications in rectal cancer surgery. J Surg Res. 2010;163:35–39.
19. Hourigan JS. Impact of obesity on surgical site infection in colon and rectal
surgery. Clin Colon Rectal. 2011;24:283–290.
20. Makino T, Shukla PJ, Rubino F, et al. The impact of obesity on perioperative
outcomes after laparoscopic colorectal resection. Ann Surg. 2012;255:228–
236.
21. Geiger TM, Muldoon R. Complications following colon rectal surgery in the
obese patient. Clin Colon Rectal. 2011;24:274–282.
22. Leonard D, Penninckx F, Fieuws S, et al. Factors predicting the quality of total
mesorectal excision for rectal cancer. Ann Surg. 2010;252:982–988.
23. Manilich E, Vogel JD, Kiran RP, et al. Key Factors associated with postoperative complications in patients undergoing colorectal surgery. Dis Colon
Rectum. 2013;56:64–71.
24. Tekkis PP, Poloniecki JD, Thompson MR, et al. Operative mortality in colorectal cancer: prospective national study. BMJ. 2003;327:1196–1201.
25. Alves A, Panis Y, Mantion G, et al. The AFC score: validation of a 4-item
predicting score of postoperative mortality after colorectal resection for cancer
or diverticulitis: results of a prospective multicenter study in 1049 patients.
Ann Surg. 2007;246:91–96.
26. Cohen ME, Bilimoria KY, Ko CY, et al. Development of an American
College of Surgeons National Surgery Quality Improvement Program: morbidity and mortality risk calculator for colorectal surgery. J Am Coll Surg.
2009;208:1009–1016.
27. Dimick JB, Ghaferi AA, Osborne NH, et al. Reliability adjustment for reporting
hospital outcomes with surgery. Ann Surg. 2012;255:703–707.
28. Thorpe H, Jayne DG, Guillou PJ, et al. Patient factors influencing conversion
from laparoscopically assisted to open surgery for colorectal cancer. Br J Surg.
2008;95:199–205.
29. Delaney CP, Pokala N, Senagore AJ, et al. Is laparoscopic colectomy applicable
to patients with body mass index >30? A case-matched comparative study with
open colectomy. Dis Colon Rectum. 2005;48:975–981.
30. Senagore AJ, Delaney CP, Madboulay K, et al. Laparoscopic colectomy in
obese and nonobese patients. J Gastrointest Surg. 2003;7:558–561.
31. Pikarsky A, Saida Y, Yamaguchi T, et al. Is obesity a high-risk factor for
laparoscopic colorectal surgery? Surg Endosc. 2002;16:855–858.
32. Gervaz P, Bandiera-Clerc C, Buchs NC, et al. Scoring system to predict the risk
of surgical-site infection after colorectal resection. Br J Surg 2012;99:589–595.
33. Merkow RP, Bilimoria KY, McCarter MD, et al. Effect of body mass index
on short-term outcomes after colectomy for cancer. J Am Coll Surg. 2009;208:
53–61.
34. Vaccaro CA, Vaccarezza H, Rossi GL, et al. Body surface area: a new predictor
factor for conversion and prolonged operative time in laparoscopic colorectal
surgery. Dis Colon Rectum. 2012;55:1153–1159.
35. Karliczek A, Jesus EC, Matos D, et al. Drainage or nondrainage in elective
colorectal anastomosis: a systematic review and meta-analysis. Colorectal Dis.
2006;8:259–265.
36. Urbach DR, Kennedy ED, Cohen MM. Colon and rectal anastomoses do not
require routine drainage: a systematic review and meta-analysis. Ann Surg.
1999;229:174–180.
37. Benoist S. La transfusion périopératoire en chirurgie colorectale. Ann Chir.
2005;130:365–373.
38. Dionigi G, Rovera F, Boni L, et al. The impact of perioperative blood transfusion on clinical outcomes in colorectal surgery. Surg Oncol. 2007;16:177–182.
39. Martling A, Granath F, Cedermark B, et al. Gender differences in the treatment of rectal cancer: a population based study. Eur J Surg Oncol. 2009;35:
427–433.
40. Muscari F, Suc B, Msika S, et al. Surgeon-dependent predictive factors for mortality after elective colorectal resection and immediate anastomosis for cancer
C 2013 Lippincott Williams & Wilkins
Waist/Hip Ratio and Colorectal Surgery
or nonacute diverticular disease: multivariable analysis of 2,605 patients. J Am
Coll Surg. 2008;207:888–895.
41. Naboush A, Hamdy O. Measuring visceral and hepatic fat in clinical practice
and clinical research. Endocr Pract. 2013;19:587–589.
DISCUSSANTS
P. Ronan O’Connell (Dublin, Ireland):
I would like to thank the association for the opportunity to
comment on this article. In an age of increasing complexity and cost,
it really is refreshing to hear that simple measurements such as WC
and WHR are predictive of intra- and postoperative complications.
I would like to congratulate the authors for conducting such a large
study that includes patients from 11 countries, 38 centers, and 60
surgeons. In 1 year, you were able to obtain information on 1349
patients who underwent elective colorectal resection. However, if you
explore these data, you find that given the large number of centers
concerned, this actually equates to only 30 patients per center. We
know that many of the centers are high volume, some of them doing
100 or even 200 colorectal resections per year. So, does this raise
concern regarding the study design and the potential for selective
patient recruitment? How was the sample size determined, did you
do some form of power calculation, and how confident can you be
that the study cohort represents a representative sample of the patient
populations in the individual institutions that partook?
Now quite apart from the anthropometric data, the surgical outcomes are extraordinarily good, even accepting they are reported from
institutions with specialized colorectal interest. The overall mortality
of less than 1%, surgical morbidity of less than 18%, and abdominal wall complication rate of 5% are exceptionally low. Could it be
that these outstanding results are again related to selection inclusion
of patients, or could it be that the follow-up of these patients was
incomplete?
In that regard, the wound infection rate is truly very low for
colorectal resection. Data from my own unit show that the superficial
wound infection rate was 7% at time of hospital discharge, but if you
did a detailed 30-day follow-up on these patients, it doubled. How
confident are you that the data you present are robust? Was there
careful follow-up of these patients after they had been discharged
such that we actually know that the data presented are real in terms
of the complication rates?
The last point is that I would like to know how you feel the
anthropometric data might be used to alter surgical practice. It would
seem that even if WC can predict higher laparoscopic conversation
rate and greater overall surgical complication rate, it is not a variable
that we can modify in the short term. When faced with a patient
with colorectal cancer or symptomatic diverticular disease, it is not
immediately apparent to me how the information might be used to
improve patient care. Thank you.
Reply From A.H. Kartheuser (Brussels, Belgium):
Thank you very much for these comments and of course you
raised a very important question concerning the validity of the data.
Regarding the study design, we did not have any preexisting data
about WC and WHR related to colorectal surgery in the literature, so
this is a preliminary study that opens the way for many other studies.
We did not have a comparison between BMI and WHR, so we had
a lot of discussion with our statistician and we decided that it was
impossible to make a power calculation. So, we decided to go for
more than a thousand to have a population as big as we can. That is
why the study took quite a while.
The second one is about surgeon compliance and bias. Of
course, there can be a bias, but we think it is unlikely, as there are
no data favoring one anthropometric measure or the other. A surgeon
www.annalsofsurgery.com | 729
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Kartheuser et al
may not include the worst patient or the major complication, but it
should not impact what we were looking at and that was the impact
on morbidity of waist, hip, and WHR.
One of the authors did the data collection for the 4 major centers
and collected more than 25% of the data. Six centers collected more
than 50% of patients’ data, so for these centers we are quite confident
about the inclusion rate, but, of course, for small centers, it is quite
difficult to be completely sure that we do not have any bias.
Regarding how to use the information, for benign disease,
we can of course give advice regarding weight loss, but we need
further study to find the optimum values of WC and WHR for use
in the clinical practice. For patients with cancer, we cannot change
anything; we can just counsel the patient and say you are in risk
category and these are the risks. This is a very simple, very easy, and
a very cheap way; just a tape to have maybe a good risk factor and a
very easy formula, if it is like all the score factors such as the bottom
score, if it is not easy to use, people will not use it. This is very simple
measurement and very easy to use.
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Annals of Surgery r Volume 258, Number 5, November 2013
DISCUSSANTS
D.A. Legemate (Amsterdam, The Netherlands):
Just one brief question, you did not stratify in your analysis and your study design for patients operated on for cancer
and those operated on for inflammation. Would not that be useful
to do?
Reply From A.H. Kartheuser (Brussels, Belgium):
I think that the first point regarding inflammation, we just
included diverticulitis and elective surgery for diverticulitis but not
inflammatory bowel disease. This is a global population study, but of
course what you say is very important, to look at subgroups: cancer
versus noncancer, or colon cancer versus rectal cancer, or laparoscopy
approach versus open approach, or male versus female sex. This has
to be done, but I am afraid that if you look at the subgroups, we do
not have sufficient numbers. So, this is again an opening for further
studies. Thank you.
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