Clinical utility of preoperative screening with STOP-Bang questionnaire in elective surgery

Abstract

Background:
Obstructive sleep apnea (OSA) is a common disease which increases the risk of perioperative complications. The aim of this study is to assess the clinical utility of preoperative screening for OSA in determining the prevalence of patients at high risk of OSA in a surgical population, the incidence of difficult airway management and the incidence of perioperative complications.

Methods:
We conducted a multisite, prospective observational study on adult patients scheduled for elective surgery. All patients completed a STOP-Bang questionnaire as a part of their preoperative evaluation. Collected data included: demographic data, type of surgery, ASA class, postoperative course, complications within 48 hours, difficult intubation (DI) and difficult mask ventilation (DMV) rates.

Results:
A total of 3452 consecutive patients were recruited; 2997 (87%) were identified as low OSA risk patients and 455 (13%) were identified as high OSA risk patients; 113 (3%) postoperative complications, 315 (9%) cases of DMV and 375 (11%) of DI were observed. The percentage of postoperative complications in patients with HR-OSA was 9%, while the percentage of DI was 20% and the percentage of DMV was 23%. High risk for OSA and higher BMI (≥30 Kg m-2) were independently associated with risk for perioperative complications.

Conclusion:
In conclusion, this study demonstrates that the prevalence of high OSA risk patients in the surgical population is high. The increase in the rates of perioperative complications justifies the implementation of perioperative strategies that use the STOP-Bang as a tool for triage.

Full text

Vol. 80 - No. 8 MINERVA ANESTESIOLOGICA 877
ORIGINAL ARTICLE
Anno: 2014
Mese: August
Volume: 80
No: 8
Rivista: MINERVA ANESTESIOLOGICA
Cod Rivista: Minerva Anestesiol
Lavoro:
titolo breve: Clinical utility of preoperative screening with STOP-Bang questionnaire
primo autore: CORSO
pagine: 877-84
Obstructive sleep apnea (OSA) refers to a
condition characterised by repetitive inter-
ruptions to breathing due to obstruction of the
upper airway in sleep. Twenty-six percent of the
US adult population is thought to be at high risk
for OSA.1 In most cases, the frequency of OSA in
surgical populations is substantially higher than in
the general population, with values ranging from
70% among bariatric surgery patients to 23.7%
in general surgery patients.2-4 However, most of
these patients are undiagnosed,4 leading to an in-
crease in the risk of perioperative complications.5
e perioperative risk of patients with OSA may
be reduced by appropriate screening to detect
undiagnosed OSA and to target the correct strat-
egy for perioperative care.6 Questionnaires are the
most eective screening tools and the STOP-Bang
was validated for the preoperative screening of
OSA patients.7 e aim of this study was to assess
the clinical utility and feasibility of preoperative
Clinical utility of preoperative screening with
STOP-Bang questionnaire in elective surgery
R. M. CORSO 1, F. PETRINI 2 , M. BUCCIOLI 1, O. NANNI 3, E. CARRETTA 3, A. TROLIO 2,
D. DE NUZZO 2, A. PIGNA 4, I. DI GIACINTO 4, V. AGNOLETTI 1 , G. GAMBALE 1
1Anesthesia and Intensive Care Section, Emergency Department, “GB Morgagni-L. Pierantoni” Hospital, Forli, Forlì-
Cesena, Italy; 2Department of Perioperative Medicine, Pain, ICU and RRS Chieti University Hospital, ASL 2 Abruzzo,
Chieti, Italy; 3Biostatistics and Clinical Trials Unit, Istituto Scientico Romagnolo per lo Studio e la Cura dei Tumori
(IRST), Meldola, Forlì-Cesena, Italy; 4Anesthesia and Intensive Care Unit, Department of Surgery and Anesthesiology,
S. Orsola-Malpighi University Hospital, Bologna, Italy
ABSTRACT
Background. Obstructive sleep apnea (OSA) is a common disease which increases the risk of perioperative compli-
cations. e aim of this study is to assess the clinical utility of preoperative screening for OSA in determining the
prevalence of patients at high risk of OSA in a surgical population, the incidence of dicult airway management and
the incidence of perioperative complications.
Methods. We conducted a multisite, prospective observational study on adult patients scheduled for elective surgery.
All patients completed a STOP-Bang questionnaire as a part of their preoperative evaluation. Collected data in-
cluded: demographic data, type of surgery, ASA class, postoperative course, complications within 48 hours, dicult
intubation (DI) and dicult mask ventilation (DMV) rates.
Results. A total of 3452 consecutive patients were recruited; 2997 (87%) were identied as low OSA risk patients
and 455 (13%) were identied as high OSA risk patients; 113 (3%) postoperative complications, 315 (9%) cases
of DMV and 375 (11%) of DI were observed. e percentage of postoperative complications in patients with HR-
OSA was 9%, while the percentage of DI was 20% and the percentage of DMV was 23%. High risk for OSA and
higher BMI (≥30 Kg m-2) were independently associated with risk for perioperative complications.
Conclusion. In conclusion, this study demonstrates that the prevalence of high OSA risk patients in the surgical
population is high. e increase in the rates of perioperative complications justies the implementation of periopera-
tive strategies that use the STOP-Bang as a tool for triage. (Minerva Anestesiol 2014;80:877-84)
Key words: Sleep apnea syndromes - Postoperative complications - Surgical procedures, operative.
Comment in p. 867.
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CORSO CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE
878 MINERVA ANESTESIOLOGICA August 2014
screening for OSA in determining the prevalence
of patients at high risk of OSA in a surgical popula-
tion, the incidence of dicult airway management
and the incidence of perioperative complications.
Our hypothesis is that the high OSA risk category
is indeed characterised by a higher incidence of
perioperative complications.
Materials and methods
We conducted a multicentric, prospective
observational study on adult patients scheduled
for elective surgery at 3 centres: “S’Orsola-Mal-
pighi” University Hospital, Bologna, “SS.ma
Annunziata” University Hospital, Chieti, and
“GB Morgagni-L. Pierantoni” Hospital, Forlì,
from April 2010 to December 2011. e study
was approved by the Regional Research Eth-
ics Committee of the “GB Morgagni-L. Pier-
antoni” Hospital, Forlì, Italy (Ref: 997/2010 I
5/209-439). e approval included a waiver of
informed consent. At each participating centre,
all consecutive adult patients with an American
Society of Anesthesiologists (ASA) physical sta-
tus I-IV, who had been scheduled for elective
surgery (general surgery, gynaecology, orthopae-
dics, urology, ophthalmology, thoracic surgery,
head and neck surgery, vascular surgery), were
considered for inclusion. Exclusion criteria were:
patients with documented OSA, paediatric pa-
tients, sleep apnoea surgery, regional anaesthesia,
ambulatory surgery. Documented OSA was de-
ned as OSA diagnosis based on a previous labo-
ratory or portable PSG, or on the prescription
of continuous positive airway pressure (CPAP)
for OSA. All patients completed a STOP-Bang
questionnaire as part of their preoperative medi-
cal assessment (Appendix). e anesthetists and
surgeons taking part in the clinical care of the
patient were not blinded to the STOP-Bang
questionnaire results, however participating cen-
tres did not have a standardized protocol for the
anesthesiological management of these patients
at the time of the present study. Case record
forms for individual patients were compiled at
the individual centres. Participating centres sent
an anonymous le with their own data to the
Data Manager (M.B.) on a monthly basis. e
nal database was anonymized through the dele-
tion of patients’ identity and other sensitive data
and assigning to each patient a unique identi-
er. A dedicated web site was created to facili-
tate communication between the investigators.
Collected data included demographic data,
type of surgery, ASA class, postoperative course,
complications within 48 hours, dicult intuba-
tion (DI) and dicult mask ventilation (DMV)
rates. Obesity was dened as a Body Mass Index
(BMI, calculated as weight in kilograms divided
by height in meters squared) of over 30. In ac-
cordance with Italian Dicult Airway Manage-
ment Guidelines,8 the DI was dened as a ma-
noeuvre performed with a correct head position
and external laryngeal manipulation resulting
in: a) dicult laryngoscopy, dened as being
characterized by the impossibility of obtaining
a view of the vocal cords even after the best ex-
ternal laryngeal manipulation; b) necessity of
repeated attempts; c) necessity of non standard
devices and/ or procedures; d) withdrawal and
procedure re-planning. Accordingly, a single
repeated attempt or switch to a dierent blade
qualies as dicult intubation. Standard equip-
ment is specied as the Macintosh laryngoscope
and simple endotracheal tube; all other devices,
such as videolaryngoscopes or procedures, such
as the use of supraglottic airway devices as a con-
duit for tracheal intubation, are dened as non-
standard.8 Refer to the Appendix for a copy of
the STOP-Bang questionnaire. Chieti was the
only centre to record type of complication (res-
piratory, cardiac, etc.), whereas all other centres
recorded the total number of complications; in
cases with more than one complication, only the
most serious type of complication was recorded.
Pulmonary complications included hypoxemia,
atelectasis, pulmonary embolism, or pneumo-
nia. Hypoxemia was dened as a decrease in the
oxyhemoglobin saturation (SpO2<90% for more
than 1 minute) and/or cyanosis and/or PaO2<60
mmHg. Cardiac complications included new-
onset arrhythmia, systemic hypotension and/or
hypertension, or myocardial ischemia. Systemic
hypotension was described as a decrease in systolic
blood pressure to less than 90 mmHg for more
than 5 minutes. Systemic hypertension was de-
scribed as an increase in systolic blood pressure
greater than 200 mmHg for more than 5 min-
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CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE CORSO
Vol. 80 - No. 8 MINERVA ANESTESIOLOGICA 879
between low risk and high risk patients for OSA
were evaluated by means of the χ2 test or Fisher
exact test. e Wald method was used to calculate
the condence interval (CI) of the binomial pro-
portion of postoperative complications, dicult
tracheal intubation and dicult mask ventilation.
Multivariate logistic regression models were car-
ried out to assess the adjusted risks of outcomes
for patients at a high risk of OSA, compared to
low risk patients. A stepwise backward elimina-
tion procedure of non-signicant explanatory fac-
tors was adopted to identify the most signicant
variables to be included in the models, alongside
patient age and gender. In order to identify pos-
sible eect modiers, interaction terms between
patient characteristics and risk for OSA were also
explored. Secondary analysis for possible eect
modiers was performed using a stratied logis-
tic regression model. Odds ratios (ORs) and 95%
condence intervals for each variable included in
the models were calculated. A P value of less than
0.05 was considered statistically signicant.
Sample size calculation
Based on our pilot study, we estimated that
14% of the population has a high risk score for
OSA (STOP-Bang Score ≥5). Upon calculating
sample size, we considered a two group continu-
ity corrected χ2 test with a 0.05 two-sided alpha-
error. A sample of 201 patients was estimated to
have a 90% power to detect a prevalence of com-
plication of 20% in those with high risk and 2%
in those with low risk scores, as reported by Vasu
et al.9 e post hoc power analysis highlighted a
99% power to detect the results observed in this
study on postoperative complications.
Results
During the study period, a total of 3452 con-
secutive patients completed all the items of the
STOP-Bang questionnaire. Among this patient
cohort, 2997 (87%) were identied as low OSA
risk patients and 455 (13%) were identied as
high OSA risk patients. Patient characteristics
between patient groups are summarized in Table
I. Table II lists the types of operations performed
on the study participants. Patients with a high
utes. Myocardial ischemia was dened by a de-
pression of ST greater than 1 mm and/or inver-
sion of the T wave in a 12-lead ECG. Neurologic
complications included a perioperative diagnosis
of cerebral stroke and confusion. Confusion was
described as new-onset disorientation in time/
place/person for more than 30 minutes.
Pilot study
e STOP-Bang questionnaire was admin-
istered to 600 preoperative clinic patients at the
Forlì center during a feasibility study. We adopted
two cut-os to classify patients as at high or low
risk of having OSA (≥3 and ≥5). Using a score
of ≥3, the prevalence of high risk patients was of
47%, similar to Vasu’s study.9 Using a cut-o ≥5,
the prevalence decreased to 14%. Although the
STOP-Bang with a cut o ≥3 is helpful in ruling
out patients with moderate and severe OSA, its
sensitivity being 92.9% and 100% for moderate
and severe OSA respectively, the specicity at the
same cut-o is low, resulting in high false-positive
rates.7 is “balancing act” is a major challenge
in using the STOP-Bang to establish a periopera-
tive care pathway in daily practice; indeed inap-
propriate use may lead to a risk of overcrowding
the postanaesthesia care unit and critical care envi-
ronments. However Farney et al. showed that the
greater the cumulative score of risk factors as re-
ected by the STOP-Bang model, the greater the
probability of severe OSA.10 Moreover, Chung et
al. showed that a score of 5 is the best compromise
between specicity and sensitivity.11 erefore, a 5
cut-o was retained as appropriate for all analysis.
Statistical analysis
Statistical analysis was performed using SAS
version 9.3 for Windows (SAS Institute, Cary,
NC, USA). e patient characteristics are pre-
sented as means±standard deviation (SD) for con-
tinuous variables and frequency and percentages
for categorical variables. e cohort of patients
was classied into two groups according to the
STOP-BANG score: a score <5 identied pa-
tients at a low risk of OSA (LR-OSA) and a score
≥5 identied patients with a high risk of OSA
(HR-OSA). Dierences in patient characteristics
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CORSO CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE
880 MINERVA ANESTESIOLOGICA August 2014
T I.—Patient characteristics data of study population. Data shown as mean±SD or number with percentage in
parenthesis.
Low risk High risk P-value*
N.=2997 N.=455
Age (T) yr 58.9±17.5 63.9±13.8
Age (>60 yr) 1577 (52.6) 299 (65.7) <0.0001
Gender (male/female) 1454/1543 (48.5/51.5) 380/75 (83.5/16.5) <0.0001
BMI (kg m-2) 25.8±4.5 31.9±5.8
BMI (≥30 kg m-2) 460 (15.3) 262 (57.6) <0.0001
ASA physical status
1 877 (29.3) 25 (5.5) <0.0001
2 1375 (45.9) 209 (45.9)
3 694 (23.1) 204 (44.8)
4 51 (1.7) 17 (3.7)
*P value was calculated using the Chi-Square test
T II.—Types of operations of study population, number with percentage in parenthesis.
Types of operations Low risk High risk P value*
N.=2997 N.=455
Abdominal 511 (17.1) 58 (12.7) <0.0001
Head and neck 1266 (42.2) 81 (17.8)
oracic 309 (10.3) 105 (23.1)
Genitourinary 434 (14.5) 100 (22)
Vascular 196 (6.5) 53 (11.7)
Orthopedic 281 (9.4) 58 (12.7)
*P value was calculated using the Chi-Square test
Figure 1.—e percentage of cases with outcomes according to the patients groups. Low risk group for OSA are patients with
STOP-Bang score<5 and High risk group for OSA are patients with STOP-Bang Score≥5.
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CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE CORSO
Vol. 80 - No. 8 MINERVA ANESTESIOLOGICA 881
ciated with risk of DI and DMV whereas in the
post operative complication model there was a
signicant interaction of gender and risk of OSA
(Table III). is statistically signicant interac-
tion between risk for OSA and gender shows
that high OSA risk male patients had a lower
risk of postoperative complication compared to
high OSA risk female patients (Table III). e
logistic model, stratied by gender, conrmed
that a high risk of OSA was associated with post
operative complication only in female strata but
the small number of women with a low risk of
OSA and postoperative complication (1.43%)
may have produced over-tted estimates (Table
IV) and should be interpreted with caution. e
analysis of complication type from the results
collected by the Chieti Centre, show that respi-
ratory complications are the most frequent, fol-
lowed by cardiac ones (Table V).
risk of OSA were older, had a higher BMI and a
higher prevalence of ASA III and IV compared
to low OSA risk patients. During the study pe-
riod, 113 (3%) postoperative complications,
315 (9%) cases of DMV and 375 (11%) cases
of DI were observed. As shown in Figure 1, the
percentage of postoperative complications in pa-
tients with HR-OSA was 9% (95% CI: 6-11%),
while the percentage of DI was 20% (95% CI:
17-24%) and the percentage of DMV was 23%
(95% CI: 19-27%). High risk for OSA and
higher BMI (≥30 kg m-2) were independently
associated with risk for postoperative complica-
tions, DI and DMV (Table III). Class III or IV
for ASA predicted a 7-fold increase in postop-
erative complications and a 5-fold increased in
DMV. Class III or IV for ASA was associated
with a 31% decrease in DI compared to class I or
II for ASA (Table III). Male gender was not asso-
T III.—Adjusted risk factors for postoperative complications, dicult intubation and dicult mask ventilation.
Variable
Postoperative
complications Dicult intubation Dicult Mask ventilation
OR 95% CI OR 95% CI OR 95% CI
High vs. low risk for OSA 3.98 (1.69-9.37) 1.86 (1.37-2.51) 2.06 (1.51-2.83)
Age ≥60 vs. <60 yr 1.26 (0.83-1.89) 1.21 (0.97-1.51) 1.06 (0.83-1.37)
Gender male vs. female 2.66 (1.57-4.49) 1.00 (0.80-1.26) 1.05 (0.81-1.37)
BMI ≥30 vs. <30 kg m-2 2.24 (1.43-3.50) 2.25 (1.75-2.89) 2.29 (1.74-3.02)
ASA III-IV vs. I-II 6.98 (4.45-10.95) 0.69 (0.54-0.90) 4.94 (3.83-6.37)
Interaction term
Risk for OSA and Gender 0.28 (0.11-0.73)
OR: odds ratio; CI: condence interval from multivariate logistic regression models.
Models include the risk factors and interaction terms identied by backward elimination procedure.
T IV.—Adjusted risk factors for postoperative complications stratied by gender. OR, odds ratio; CI, condence interval
from multivariate logistic regression model.
Variable
Female
(N.=1618)
Male
(N.=1834)
OR 95% CI OR 95% CI
High vs. Low Risk for OSA 3.97 (1.55-10.14) 1.14 (0.66-1.95)
Age ≥60 vs.<60 yr 0.86 (0.41-1.83) 1.47 (0.90-2.41)
BMI ≥30 vs.<30 kg m-2 2.51 (1.07-5.85) 2.16 (1.27-3.66)
ASA III-IV vs. I-II 6.62 (2.85-15.35) 7.03 (4.12-11.99)
T V.—Types of postoperative complication in the subsample from “SS.ma Annunziata” Hospital, Chieti.
Types of postoperative complication Low risk High risk P-value*
N.=701 N.=125
Respiratory 39 (5.6) 29 (23.2) <0.0001
Cardiac 30 (4.3) 24 (19.2) <0.0001
Neurology 4 (0.6) 2 (1.6) 0.2263
*P value was calculated using the Chi-Square test or Fisher exact test as appropriate
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CORSO CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE
882 MINERVA ANESTESIOLOGICA August 2014
enables the eective identication of a high-risk
population. Currently, Vasu’s study is the only
one to have explored the clinical utility of the
STOP-Bang.9 In their study, adult patients un-
dergoing elective surgery at a tertiary care centre
who were administered the STOP-Bang ques-
tionnaire for 3 consecutive days were included.
e prevalence of high risk OSA in 135 patients
included was 41.5%, conrming the high preva-
lence of high risk OSA patients among the surgi-
cal patient population. Our opinion, based on
the high number of positive screening, is that
this study included a high percentage of over-
triage with a high number of false positives. In
our study, in order to reduce the overtriage, we
used a cut-o of the STOP-Bang score which
was greater or equal to ve; in this way we ob-
tained a lower High Risk prevalence (13% vs
41.5%), compatible with screening require-
ments11. Several studies have shown the elevated
incidence of dicult intubation in OSA pa-
tients 17,18. e main limitation of these studies
is that they are all retrospective, therefore they
can only infer an association between OSA and
dicult intubation. Up to now, the only pro-
spective study conducted has failed to identify
OSA as a risk factor for DI among patients with
a conrmed diagnosis of OSA19. In our study,
the incidence of DI is 20% in the high risk group
compared to 9% in the low risk group, thus con-
rming the hypothesis that patients identied as
being at high risk of OSA are more likely to have
a DI. e link between OSA and dicult venti-
lation with DMV face mask is just as important,
although the object of a lower number of stud-
ies. Kheterpal et al.20 reported an incidence of
impossible mask ventilation of 0.15% in an ob-
servational study of over 50,000 general anaes-
thetic procedures. A history of OSA was found
to be an independent predictor of impossible
mask ventilation. Interestingly, the opposite also
appears to be true: in a prospective study, Plun-
kett et al. 21 found that nine out of ten patients
exhibiting dicult ventilation at the time of an-
aesthesia induction were proven to be aected by
OSA. In our study, high OSA risk patients dem-
onstrated a higher incidence of DMV (23% vs
7%), justifying, together with the higher inci-
dence of DI, the need for clinicians to have im-
Discussion
Our results conrm that the prevalence of
high OSA risk patients in the surgical popula-
tion is high and that they have an increased rate
of perioperative complications.
is is the rst large prospective study, to our
knowledge, to investigate the clinical utility of
the STOP-BANG questionnaire. OSA is a com-
mon pathology; Young et al.12 reported that
symptomatic OSA aects approximately be-
tween 2% and 4% of middle-aged women and
men respectively, but the overall prevalence of
sleep-disordered breathing was estimated as 9%
for women and 24% for men between the ages
of 30 and 60. is makes OSA more common
than asthma among adults. Furthermore, an es-
timated 82% of men and 93% of women with
OSA remain undiagnosed.13 It would appear
that there is a higher prevalence of OSA among
the surgical patient population; OSA prevalence
varies according to type of surgery, peaking
among bariatric surgery patients3. In spite of
this, surgeons and anaesthetists are often una-
ware of this pathology. Singh et al.14 in a histori-
cal cohort study on 819 patients, showed that
anaesthetists and surgeons failed to identify a
signicant number of patients with pre-existing
OSA and symptomatic undiagnosed OSA, be-
fore surgery. e probability of adverse outcomes
may increase when care providers are unsuspect-
ing of patients aected by this pathology and
thus unable to identify and undertake appropri-
ate preventative precautions for such patients.
erefore, it is crucial for anaesthetists to screen
every patient scheduled for surgery for OSA in
order to adopt the correct strategy for periopera-
tive care. In-laboratory polysomnography
(PSG)15 is still the gold standard for the diagno-
sis of OSA, however costs, waiting lists and low
availability in all hospitals render it unusable as a
screening tool. Among screening tools for OSA,
three have been validated for application on sur-
gical patients: the Berlin Questionnaire, the
American Society of Anesthesiologists (ASA)
Checklist, and the STOP Questionnaire16. Out
of these three questionnaires, the quickest and
the simplest to use is the STOP-Bang Question-
naire.7 A screening test is clinically useful when it
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This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.

CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE CORSO
Vol. 80 - No. 8 MINERVA ANESTESIOLOGICA 883
erative complications in OSA patients is attrib-
utable to the particular sensitivity of such pa-
tients to anaesthetic drugs and in particular to
opioids.25 REM rebound has also been investi-
gated 26 as a potential explanation for the higher
frequency of hypoxemic episodes in the postop-
erative phase. An interesting result of the study
was the link between female patients and the in-
cidence of postoperative complications. While
bearing in mind limitations of the statistical
analysis, it is important to note that this data
conrms the results of Ye et al.27 In a secondary
analysis of data from a multisite study, they
found that women with OSA showed greater
impairment in daytime functioning and apnoea
symptoms than men. It would be logical to sug-
gest, therefore, that women aected by OSA are
more vulnerable to postoperative complications,
however further research on this matter is re-
quired. is study has several strengths. It is the
rst study to prospectively evaluate the clinical
usefulness of the STOP-Bang with a considera-
ble population of patients. It shows the clinical
usefulness of the STOP-Bang questionnaire as a
screening tool in terms of identication of risk of
perioperative complications and demonstrates
the organisational sustainability of screening all
patients scheduled for elective surgery. Its major
limitation is that operators were not blinded to
the results of the STOP-Bang questionnaire.
erefore we cannot exclude an important bias
in the behaviour of operators. Indeed, it is likely
that anaesthetists have implemented periopera-
tive precautions in the group of patients at high
risk for OSA, reducing the rate of complications.
Conclusions
In conclusion, this study demonstrates that
the prevalence of high OSA risk patients in the
surgical population is high. e study also dem-
onstrates the organizational sustainability of a
wide-scale screening, using a simple question-
naire such as the STOP-Bang. e increase in
the rates of postoperative complications and dif-
cult airway management among high OSA risk
patients justies the implementation of periop-
erative strategies that use the STOP-Bang as a
tool for triage.
mediate access to alternative techniques to venti-
late the patient and secure the airway. e nal
multivariate logistic regression shows that obesi-
ty is a risk factor in terms of diculty of airway
management (DI and DMV), and our study
conrms data of literature.22 Data showing that
the ASA III-IV class is associated with a reduc-
tion in the risk of DI such as the ndings of
Fourth National Audit Project in which the ma-
jority of patients involved in anaesthesia cases
were ASA grade 1 or 2 (56%).22 A possible ex-
planation may be that anaesthetists may fail to
recognise a potentially dicult airway in appar-
ently healthy patients (ASA grade I-II), thus in-
creasing the likelihood of them having to face an
unexpected DI. Until now, no link between ASA
class III-IV and DMV has been found and fur-
ther studies are necessary. Lastly, the incidence of
postoperative risks was highest in the high risk
patient group. Literature has previously shown
that there are connections between OSA and
postoperative complications,23 however most
studies were retrospective, carried out on small
samples and often concerned a restricted number
of types of surgery. Currently, only limited pro-
spective data exist on perioperative complica-
tions in patients with undiagnosed OSA under-
going non-airway surgeries. To date, Vasu’s study
is the only one to demonstrate a higher incidence
of postoperative complications in patients who
have been identied as high OSA risk using the
STOP-Bang.9 is study shows that a high risk
assessment through the STOP-Bang increases
the risk of postoperative complications. e
study’s main limit is the fact that it was conduct-
ed retrospectively thus with a higher risk of er-
rors of omission and methodological inconsist-
encies. Our results show a strong link between a
state of high OSA risk and postoperative compli-
cations. e analysis of a subgroup in one centre
showed that the most common complications
were of a respiratory nature, thus conrming
data in literature.24 Vasu’s study 9 reported an in-
cidence of complication of 19.6% in the high
risk group, compared to 9% in our study. is
dierence can be explained by the fact that our
study only reported major complications; dier-
ences in denitions could also be responsible for
this discrepancy. e high frequency of postop-
COPYRIGHT© 2014 EDIZIONI MINERVA MEDICA
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.

CORSO CLINICAL UTILITY OF PREOPERATIVE SCREENING WITH STOPBANG QUESTIONNAIRE
884 MINERVA ANESTESIOLOGICA August 2014
measurements of the apnea/hyponea index. J Clin Sleep Med
2011;7:459-65.
11. Chung F, Subramanyam R, Liao P, Sasaki E, Shapiro C, Sun
Y. High STOP-Bang score indicates a high probability of ob-
structive sleep apnoea. Br J Anaesth 2012;108:768-75.
12. Young T, Palta M, Dempsey J, Skatrud J, Weber S, Badr S.
e occurrence of sleep-disordered breathing among middle-
aged adults. New Engl J Med 1993;328:1230-5.
13. Young T, Evans L, Finn L, Palta M. Estimation of the clini-
cally diagnosed proportion of sleep apnea syndrome in mid-
dle-aged men and women. Sleep 1997;20:705-6.
14. Singh M, Liao P, Kobah S, Wijeysundera DN, Shapiro C,
Chung F. Proportion of surgical patients with undiagnosed
obstructive sleep apnoea. Br J Anaesth 2013;110:629-36.
15. Fleetham J, Ayas N, Bradley D, Ferguson K, Fitzpatrick M,
George C et al. CTS Sleep Disordered Breathing Committee.
Canadian oracic Society guidelines: diagnosis and treat-
ment of sleep disordered breathing in adults. Can Respir J
2006;13:387-92.
16. Chung F, Yegneswaran B, Liao P, Chung SA, Vairavanathan
S, Islam S et al. Validation of the Berlin questionnaire and
American Society of Anesthesiologists checklist as screening
tools for obstructive sleep apnea in surgical patients. Anesthe-
siology 2008;108:822-30.
17. Kim JA, Lee JJ. Preoperative predictors of dicult intuba-
tion in patients with obstructive sleep apnea syndrome. Can
J Anaesth 2006;53:393-7.
18. Corso RM, Piraccini E, Calli M, Berger M, Gorini MC,
Agnoletti V et al. Obstructive sleep apnea is a risk factor
for dicult endotracheal intubation. Minerva Anestesiol
2011;77:99-100.
19. Neligan PJ, Porter S, Max B, Malhotra G, Greenblatt EP,
Ochroch EA. Obstructive sleep apnea is not a risk factor for
dicult intubation in morbidly obese patients. Anesth Analg
2009;109:1182-6.
20. Kheterpal S, Martin L, Shanks AM, Tremper KK. Prediction
and outcomes of impossible mask ventilation: a review of
50,000 anesthetics. Anesthesiology 2009;110:891-7.
21. Plunkett AR, McLean BC, Brooks D, Plunkett MT, Mikita
JA. Doesdicultmaskventilation predict obstructivesleep
apnea? A prospective pilot study to identify the prevalence of
OSA in patients withdicultmaskventilationunder general
anesthesia. J ClinSleepMed 2011;7:473-7.
22. Woodall NM, Cook TM. National census of airway manage-
ment techniques used for anaesthesia in the UK: rst phase
of the Fourth National Audit Project at the Royal College of
Anaesthetists. Br J Anaesth 2011;106:266-71.
23. Kaw R, Chung F, Pasupuleti V, Mehta J, Gay PC, Hernan-
dez AV. Meta-analysis of the association between obstruc-
tive sleep apnoea and postoperative outcome. Br J Anaesth
2012;109:897-906.
24. Memtsoudis S, Liu SS, Ma Y, Chiu YL, Walz JM, Gaber-Bay-
lis LK et al. Perioperative pulmonary outcomes in patients
with sleep apnea after noncardiac surgery. Anesth Analg
2011;112:113-21.
25. Ankichetty S,Wong J,Chung F.A systematic review of the ef-
fects of sedatives and anesthetics in patients with obstructive
sleep apnea. J Anaesthesiol Clin Pharmacol2011;27:447-58.
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Kehlet H. Late postoperative nocturnal episodic hypoxaemia
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27. Ye L, Pien GW, Ratclie SJ, Weaver TE. Gender dierences
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Key messages
—e prevalence of high OSA risk pa-
tients in the surgical population is high.
—A wide-scale preoperative screening
with STOP-Bang questionnaire is feasible.
—e patients identied as at High Risk
for OSA have a higher risk of perioperative
complications.
—e STOP-Bang screening may help
the perioperative team to establish a correct
strategy to reduce the risk of adverse events.
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Conicts of interest.—e authors certify that there is no conict of interest with any nancial organization regarding the material discussed
in the manuscript.
Received on April 16, 2013. - Accepted for publication on October 30, 2013.
Corresponding author: R. M. Corso, MD, Anesthesia and Intensive Care Section, Emergency Department, “G.B. Morgagni-Pierantoni”
Hospital, Forlì, Forlì-Cesena, viale Forlanini 34, 47100 Forlì, Forlì-Cesena, Italy. E-mail: rmcorso@gmail.com
COPYRIGHT© 2014 EDIZIONI MINERVA MEDICA
This document is protected by international copyright laws. No additional reproduction is authorized. It is permitted for personal use to download and save only one file and print only one copy of this Article. It is not permitted to make additional copies
(either sporadically or systematically, either printed or electronic) of the Article for any purpose. It is not permitted to distribute the electronic copy of the article through online internet and/or intranet file sharing systems, electronic mailing or any other
means which may allow access to the Article. The use of all or any part of the Article for any Commercial Use is not permitted. The creation of derivative works from the Article is not permitted. The production of reprints for personal or commercial use is
not permitted. It is not permitted to remove, cover, overlay, obscure, block, or change any copyright notices or terms of use which the Publisher may post on the Article. It is not permitted to frame or use framing techniques to enclose any trademark, logo,
or other proprietary information of the Publisher.