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Med J Malaysia Vol 75 No 2 March 2020 117
ABSTRACT
Objective: To demonstrate SLEEP-GOAL as a more holistic
and comprehensive success criterion for Obstructive Sleep
Apnoea (OSA) treatment.
Methods: A prospective 7-country clinical trial of 302 OSA
patients, who met the selection criteria, and underwent
nose, palate and/or tongue surgery. Pre- and post-operative
data were recorded and analysed based on both the Sher
criteria (apnoea hypopnea index, AHI reduction 50% and
<20) and the SLEEP-GOAL.
Results: There were 229 males and 73 females, mean age of
42.4±17.3 years, mean BMI 27.9±4.2. The mean VAS score
improved from 7.7±1.4 to 2.5±1.7 (p<0.05), mean Epworth
score (ESS) improved from 12.2±4.6 to 4.9±2.8 (p<0.05),
mean body mass index (BMI) decreased from 27.9±4.2 to
26.1±3.7 (p>0.05), gross weight decreased from 81.9±14.3kg
to 76.6±13.3kg. The mean AHI decreased 33.4±18.9 to
14.6±11.0 (p<0.05), mean lowest oxygen saturation (LSAT)
improved 79.4±9.2% to 86.9±5.9% (p<0.05), and mean
duration of oxygen <90% decreased from 32.6±8.9 minutes
to 7.3±2.1 minutes (p<0.05). The overall success rate (302
patients) based on the Sher criteria was 66.2%. Cross-
tabulation of respective major/minor criteria fulfilment,
based on fulfilment of two major and two minor or better, the
success rate (based on SLEEP-GOAL) was 69.8%. Based
solely on the Sher criteria, 63 patients who had significant
blood pressure reduction, 29 patients who had BMI
reduction and 66 patients who had clinically significant
decrease in duration of oxygen <90% would have been
misclassified as “failures”.
Conclusion: AHI as a single parameter is unreliable.
Assessing true success outcomes of OSA treatment,
requires comprehensive and holistic parameters, reflecting
true end-organ injury/function; the SLEEP-GOAL meets
these requirements.
KEY WORDS:
OSA, sleep apnoea, surgical outcomes, success rate, AHI
INTRODUCTION
Obstructive sleep apnoea (OSA) is a common illness affecting
9% of middle age men and 3% of women in North America.1
It is a condition that affects the patient’s cardio-vascular,
psychomotor and neurological systems. It is estimated that
up to 93% of females and 82% of males with moderate to
severe OSA remain undiagnosed.2There is a link between
OSA and hypertension,3cardiovascular diseases,4and
congestive heart failure.5Neurologic function in OSA patients
are also affected, they are less resistant to hypoxia and may
be more prone to the effects of sleep disruption.
The gold standard diagnostic test for OSA is overnight
polysomnography (PSG). Where the frequency of obstructive
events is reported as the apnoea hypopnea index (AHI); the
severity of the OSA is classified based on the number of
apnoea and hypopnea events per hour. As a consequence,
the effectiveness of each and/or combined surgical
interventions for OSA is almost exclusively based on the
reported changes in AHI post-operatively, based on a specific
arbitrarily 50% reduction in AHI and an AHI below 20. This
is commonly known as the Sher’s success criteria.6However,
recent evidence has shown that there is a consistent
discordance between the levels of AHI used to denote
outcomes/success of therapy and real-world clinical outcomes
such as quality of life (QoL), patient perception of disease,
cardiovascular measures (e.g., blood pressure, oxygen
saturation, and/or survival.7Moreover, in many areas of
medicine patient-reported outcome measures and QoL
assessments are gaining substantial traction as priority items
to assess, when gauging effect of therapy for all manner of
diseases;7yet in the case of OSA the AHI remains
paradoxically persistent as the main, and frequently the
only, outcome measure. The issues with utilising purely the
AHI from a “one-night only” sleep study, include its night-to-
SLEEP-GOAL: A multicenter success criteria outcome
study on 302 obstructive sleep apnoea (OSA) patients
Kenny P. Pang, FRCSEd, FRCSI1, Peter M Baptista J, MD, PhD2, Ewa Olszewska, MD, PhD3, Itzhak Braverman,
MD4, Marina Carrasco-Llatas, MD, PhD5, Srivinas Kishore, MBBS, MS6, Sudipta Chandra, MBBS, MS7, Hyung
Chae Yang, MD, PhD8, Yiong Huak Chan, BSc PhD9, Kathleen Ann Pang10, Edward Benjamin Pang11, Brian
Rotenberg, MD, MPH, FRCSC12
1Department of Otolaryngology, Asia Sleep Centre, Paragon, Singapore, 2Department of Otolaryngology, Clinica Universidad de
Navarra, Pamplona, Navarra, Spain, 3ENT Department, Medical University of Bialystok, Poland, 4Department of
Otolaryngology Head and Neck Surgery, Hillel Yaffe Medical Center, Technion Faculty Medicine, Haifa, Israel, 5ENT
Department, Hospital Universitario Dr. Peset. Valencia. Spain, 6Otolaryngology Department, Nova Specialty Hospital,
Hyderabad, India, 7ENT Department, Belle Vue Clinic & Hospital, Kolkata, India, 8Otolaryngology Department, Chonnam
National University Hospital, Korea, 9Biostatistics Unit, School of Medicine, National University Singapore, Singapore,
10Department of Otolaryngology, Asia Sleep Centre, Paragon, Singapore, 11Student, Medicine Faculty, University of Glasgow,
Scotland, 12Otolaryngology Department, Western University, London, Ontario, Canada
ORIGINAL ARTICLE
This article was accepted: 24 December 2019
Corresponding Author: Dr. Kenny Pang
Email: drkpang@gmail.com
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118 Med J Malaysia Vol 75 No 2 March 2020
night variability,8-11 the first night-effect, patient anxiety, the
restriction of movements from the abundance of monitoring
wirers, and the use of different definitions of hypopnea in the
laboratory systems, and in addition, the use of different
monitoring equipment.12
Hence, the method sleep specialists measure success of any
OSA therapy needs re-evaluation considering these points,
the need for more holistic and comprehensive parameters of
success instead of the single parameter AHI. The parameter
AHI is nebulous to the patient; no patient would seek a
consult with a sleep specialist complaining that “my AHI is
high”. There is too much weightage given to a single
parameter (AHI) that has too much variability. Parameters
that affect the patient as a whole and/or those that measure
the effects of the end-organs due to the disease process, are
more accurate.
We propose the SLEEP-GOAL as a more comprehensive and
appropriate means of success measure. The objective of this
study was to align the SLEEP-GOAL parameters, demonstrate
that the SLEEP-GOAL is more holistic, comprehensive and
inclusive compared to AHI alone, and determine the level at
which is success rate is acceptable for the SLEEP-GOAL.
MATERIALS AND METHODS
Study Design
This was a non-randomised prospective multi-centre clinical
trial of consecutive patients seen in the ENT clinic for
complaints of bothersome snoring and/or symptoms of OSA,
who met the inclusion criteria, and subsequently underwent
either nose, palate and/or tongue surgery of the upper
airway. Patients were recruited from nine tertiary clinical
centres from seven countries, including Singapore, Canada,
India, Spain, Poland, Israel and Korea, from June 2016 to
February 2018.
Patient Selection
All patients underwent a comprehensive clinical assessment
including a thorough physical examination, nasoendoscopy,
and an overnight polysomnography (PSG) pre- and post-
surgery. Parameters collated were the duration of oxygen
saturation below 90%, AHI, sleep latency and lowest oxygen
saturation (LSAT).
It was ensured that all patients could read English and/or had
an English translator to help translate to their native
language when answering the questionnaires. Patients
completed the Epworth Sleepiness Scale (ESS) and a visual
analogue scale (VAS) for snoring pre- and post-surgery. The
sleep partner completed a similar VAS scale for snoring.
Quality of Life (QoL) was assessed using at least one of the
following instruments the 36-Item Short Form Survey (SF36),
the Functional Outcomes of Sleep Questionnaire (FOSQ10),
Sleep Apnea Quality of Life Index (SAQLI), and/or the
Pittsburgh Sleep Quality Index (PSQI) questionnaires. The
reaction/execution times was assessed using the
www.humanbenchmark.com/tests/reactiontime website;
which simulates a driving episode.
Clinical examination included height, weight, neck
circumference, body-mass index (BMI), and blood pressure
(pre- and post-operative); an endoscopic assessment of the
nasal cavity, posterior nasal space, oropharyngeal area, soft
palatal redundancy, uvula size and thickness, tonsillar size
and Mallampati grade. Flexible nasoendoscopy was
performed for all patients and collapse during a Mueller’s
manoeuvre was graded for the soft palate, lateral pharyngeal
walls and base of tongue.
Inclusion criteria was adult patients (>18 years old), AHI >5,
all Friedman stage, all Mallampati grades, all multi-level
collapse, all BMI, and nose, palate and/or tongue surgery. All
patients were offered continuous positive airway pressure
(CPAP) therapy, and those patients who chose CPAP were
subsequently excluded from the study. We excluded patients
who had previous upper airway surgery and/or had any
pillar implants or hypoglossal nerve implant inserted
previously or currently.
The study protocol and methodology was reviewed and
approved by the hospital Ethics Committee/Institutional
Review Board of their respective countries.
Study Intervention
All patients enrolled had either nasal, palatal and/or tongue
surgery performed at the same sitting. Nasal surgery included
either functional endoscopic sinus surgery, septoplasty,
turbinate reduction and/or turbinoplasty. Palate surgery was
performed either in the form of the
uvulopalatopharyngoplasty, anterior palatoplasty, z-plasty,
uvulo-palatal flap and/or the expansion sphincter
pharyngoplasty. Tongue surgeries included radiofrequency
tongue base ablation, midline tongue glossectomy, or tongue
base coblator channelling. Surgeries were decided by surgeon
discretion, standard practice, and the anatomy of the patient.
Outcome Measures
SLEEP-GOAL
The SLEEP-GOAL is an acronym that relates intimately with
the OSA patient’s end-organ effects and its parameters. It
measures the cardiovascular and neuro-cognitive effects of
the OSA disease process and the OSA disease load. The
parameters are presented Box 1:
Based on the medical evidence on these parameters, we
assigned SLEE as minor criteria and PGOAL as the major
criteria. The data on each parameter was collected at pre-
surgery and at one-year post-surgery.
Statistical Analysis
All analyses were performed using SPSS 24.0 with statistical
significance set at p<0.05. Descriptive statistics for the
measured parameters were presented as mean±sd. The
change in the pre-post measurements was compared using
paired T test.
RESULTS
A total of 302 patients were recruited from the nine tertiary
clinical centres in seven countries. There were 229 males and
73 females, with an average age of 42.4±17.3years. The
mean height was 1.71±0.08metres, mean weight was
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Med J Malaysia Vol 75 No 2 March 2020 119
Table I: Changes in Selected Pre-operative and Post-operative parameters (N=302)
Parameters Pre-op Post-op p-value
Mean±SD Mean±SD
Body Mass Index (BMI) 27.9±4.2 26.1±3.7 p>0.05
Gross Weight (kg) 81.9±14.3 76.6±13.3 p>0.05
Snore VAS 7.7±1.4 2.5±1.7 p<0.05
Epworth Sleepiness Score (ESS) 12.2±4.6 4.9±2.8 p<0.05
Apnoea Hypopnea Index (AHI) 33.4±18.9 14.6±11.0 p<0.05
Lowest oxygen saturation (LSAT) 79.4±9.2 86.9±5.9 p<0.05
Oxygen duration <90% (min) 32.6±8.9 7.3±2.1 p<0.05
Box 1: The parameters of SLEEP-GOAL
S = Snoring – VAS reduction by 50%
L = sleep Latency – increase by 50%-time latency
E = ESS – a reduction of 50% and below 10
E = Execution time – an improvement by 50%
P = blood Pressure – reduction of either SBP or DBP by 7mmHg or both by 5mmHg
G = Gross weight / BMI – reduction of GW by 8% or drop in BMI by 2 points
O = Oxygenation (duration of oxygen < 90%) – improvement by 50%
A = AHI – reduction by 50%
L = Life quality (QOL) score – improvement by 50%
Table II: Cumulative percentage and success rates based on the various major and minor criteria fulfilled
Criteria Fulfilled Cumulative Percent Success Rate (%)
None .4 100.0
1 minor only 3.3 100-0.4=99.6
2 minor only 5.8 100-3.3=96.7
1 major only 6.2 100-5.8=94.2
1 major + 1 minor 10.7 100-6.2=93.8
1 major + 2 minor 16.9 100-10.7=89.3
1 major + 3 minor 17.8 100-16.9= 83.1
2 major + 1 minor 30.2 100-17.8=82.2
2 major + 2 minor 42.1 100-30.2=69.8
2 major + 3 minor 46.7 100-42.1=57.9
3 major + 1 minor 58.7 100-46.7=53.3
3 major + 2 minor 71.9 100-58.7=41.3
3 major + 3 minor 77.3 100-71.9=28.1
4 major + 1 minor 83.1 100-77.3=22.7
4 major + 2 minor 95.5 100-83.1=16.9
4 major + 3 minor 100.0 100-95.5=4.5
Note: Minor goal: Snoring VAS score reduction by 50%; sleep Latency - increase by 50% time-latency; Epworth Sleepiness Scale (ESS) - a reduction of 50%
and below 10; Execution time – an improvement by 50%. Major goal - blood pressure (BP) - reduction of either Systolic BP or Diastolic BP by 7mmHg or both
by 5mmHg; Gross weight - reduction by 8%; body-mass index (BMI) drop by 2 points; Oxygenation (duration of oxygen <90%) - improvement by 50%; apnoea
hypopnea index (AHI) - reduction by 50%; Quality of Life score - improvement by 50%.
Table III: Blood pressure, gross weight, body-mass index (BMI) and oxygen saturation changes and Apnoea Hypopnea Index (AHI)
reduction by 50% and AHI<20
Changes in parametres AHI reduction by 50% Total
AHI<20
No (n, %) Yes (n, %) (n, %)
SBP/DBPaYES 63, 20.9% 147, 48.7% 201, 69.5%
NO 39, 12.9% 53, 17.5% 92, 30.5%
Gross weightbYES 25, 8.3% 96, 31.8% 121, 40.1%
NO 77, 25.5% 104, 34.4% 181, 59.9%
BMIc YES 29, 9.6% 106, 35.1% 135, 44.7%
NO 73, 24.2% 94, 31.1% 167, 55.3%
Oxygen saturationdYES 66, 21.8% 154, 51.0% 220, 72.8%
NO 43, 14.4% 39, 12.8% 82, 27.2%
a) reduction of either systolic blood pressure (SBP) or diastolic blood pressure (DBP) by 7mmHg or both by 5mmHg
b) reduction of gross weight by 8%
c) drop in BMI by 2 points
d) Oxygen saturation <90% duration, reduction by 50%
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120 Med J Malaysia Vol 75 No 2 March 2020
81.9±14.3kg, with mean BMI 27.9±4.2. There was statistically
significant improvement in the post-operative snore VAS
score, ESS, AHI, LSAT, and mean oxygen duration of less than
90%. (Table I). There was also improvement in the BMI, gross
weight and mean sleep latency, however, the results were not
statistically significant. (Table I)
The overall success rate based on the Sher’s criteria was
66.2%. Based on the Sher’s criteria of 66.2%, as stipulated in
our objectives, we set out a target range of within 65 to 69%
(approximate) as a reasonable success range for the SLEEP-
GOAL. The cumulative percentage and success rates based on
the various major and minor criteria is presented in Table II.
The fulfilment of at least two major and two minor criteria
was deemed successful as treatment for patients with OSA as
it has achieved the Sher’s criteria of 66.2%.
Major Criteria – (PGOAL)
The achievement of the major criteria in the SLEEP-GOAL is
presented in Table III.
Around 70 per cent achieved the reduction in SBP and/or DBP
of ≥7mmHg, 40.1% had a reduction of gross weight by 8%,
44.7% had a reduction of BMI by two points, and 72.8% had
their oxygen <90% duration reduced ≥50% (Table III). Based
on the old Sher’s success criteria only 48.7% has achieved
reduction of SBB and/or DBP, 31.8% reduction in gross
weight, 35.1% reduction in BMI and 51.0% had their oxygen
<90% duration reduced ≥50%, which would have been
deemed as “unsuccessful” (Table III).
Apnoea Hypopnea Index
There was a 66.2% reduction in AHI by 50% and less than 20
in this group of 302 patients. When considering the sole
reduction of AHI by 50%, there was a 74.8% (226 out of 302
patients) who met the criteria; taking note that this was only
an 8.2% increase in number (not significant statistically).
Quality of Life
Only 256 patients completed any of the QoL questionnaires,
and due to the non-standardisation of the instruments used
in different centres, hence, analysis of the data was not
meaningful. However, based on the SLEEP-GOAL criteria of
improvement by 50% in QoL scores, only 42.9% (110 out of
the 256 patients) had an improvement of at least 50% in
their respective pre-operative and post-operative QoL scores.
Minor Criteria – (SLEE)
Snore VAS – The mean pre-operative snore VAS improved
from 7.7±1.4 to 2.5±1.7 (p<0.05). In terms of the snore VAS
improving by at least 50%, there were 42.9% of the 302
patients had a reduction of their snore VAS by 50% or more.
Latency – Sleep Latency – Based on the SLEEP-GOAL criteria
of sleep latency increasing but 50% between the pre-
operative and post-operative result, only 70 patients out of
the 302 (23.1%) had their sleep latencies increased post-
intervention.
Epworth Sleepiness Score – The mean pre-operative Epworth
sleepiness score (ESS) improved from 12.2±4.6 to 4.9±2.8
(p<0.05). In terms of the ESS reducing by 50% and below 10
post-operatively, there were 195 patients out of 302 (64.6%)
who met these criteria.
Execution Time – There were only 212 patients with data on
execution time pre-operative and post-operative. Only 71
patients out of 212 (33.5%) had their execution/reaction
times improved by 50%.
DISCUSSION
This article has an arduous task of illustrating how and why
the old traditional single parameter AHI is far from ideal and
that there should be a clear paradigm shift away from the old
Sher’s success criteria as the sole success rate indicator. Our
discussion objective would be to highlight the association
between OSA and with blood pressure, gross weight, BMI,
quality of life, hypoxemia, neuro-cognitive and the cardio-
vascular systems. This will support the utilisation of the
SLEEP-GOAL as a suitable outcome measure and to illustrate
the inadequacies of the single parameter AHI.
OSA and the Blood Pressure
In patients with OSA, during the night, there are BP surges
that can be observed in both the systemic and pulmonary
circulation,13 unlike in normal people where there is a
nocturnal 10-20% dip; occasional cyclical variations of the
heart rate may also be evident; i.e., sinus
tachycardia/bradycardia, extreme cases of arrhythmias have
also been documented.14 It is also believed that through these
arrhythmias, OSA may cause sudden cardiac death.1 5
Detrimental effects of OSA on the cardiovascular system are
carried over into daytime hours, resulting in arterial
hypertension, and a high percentage of hypertension. Mainly
through its pressor effects, OSA increases the risks for stroke,
heart failure, and myocardial infarction.16 Patients with OSA
have a higher incidence of hypertension, as high as 1.5 to 2.7
times.17-1 9 Treatment of OSA patients with CPAP have
consistently and reliably showed a decrease in blood pressure,
likely due to the improvement of vascular function.20 A
randomised controlled trial (RCT) conducted by Weaver et al.,
showed patients with OSA on CPAP has a significant
reduction in DBP values from baseline by -1.93mmHg
(95%CI; -3.8 to 0.0).21
In a meta-analysis published by Bratton et al., in which the
individual data of 1,206 patients from four RCTs were
evaluated. Although CPAP treatment reduced OSA severity
and sleepiness, overall it did not to have a beneficial effect on
BP, except in those patients who used CPAP for >4 h/night;
suggesting that a minimum of 4 hours use per night is
needed.22
These literatures illustrate that effective therapy for OSA
would result in a decrease in the blood pressure of the patient.
OSA and BMI
Obese patients have a higher incidence of OSA, however,
patients with OSA may not be obese.23 Simplistically, the
anatomy of the upper airway is essentially a balance
between the soft tissues and its skeletal framework. These
patients have a “local” problem (i.e., a localised problem in
their upper airway) versus patients who have a “global”
problem (i.e., generalised obesity). There have been papers
illustrating the use of clinical prediction models as prediction
of OSA and its severity, these all include BMI.24,25 Studies have
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Med J Malaysia Vol 75 No 2 March 2020 121
also showed that in Asian patients a cranio-facial restriction
(small jaw, retrognathia) is commonly associated with OSA
(making gross weight a better reflection compared to BMI),
compared to Caucasian patients where fat deposition is
common.22 Research also demonstrate that a BMI>40 is also
a predictor of poorer surgical outcomes,26 and that obesity is
significantly associated with fat deposition in the posterior
tongue.27 Kim et al., had recently showed that the tongue fat
percentage was higher in OSA patients compared to normal
(matched BMI) subjects (42% versus 24%).28 Parapharyngeal
fat pads have also been shown to be enlarged in apneics and
to contribute to airway narrowing.29 Therefore, it is important
for the sleep specialist to appreciate that a reduction in BMI
would not only reduce the overall oxidative metabolic stress
but also, inadvertently also increase the upper airway space
in totality.
OSA and the Epworth Sleepiness Scale
The ESS is a self-reported questionnaire that evaluates the
tendency to fall asleep in eight daily situations. The ESS score
ranges from 0 to 24, and a score equal to or greater than 10
indicates excessive daytime sleepiness.30 The ESS is sensitive
for sleepiness but not specific for any particular sleep
disorder.
OSA and Quality of Life
QoL is considered one of the most fundamental patient-
reported outcomes in healthcare. The improvement in QoL is
used to determine whether any intervention should be
considered as useful, beneficial or standard of care. For most
patients with OSA, a reduction in their QoL is often reflected
by symptoms such as excessive daytime sleepiness or fatigue,
poor sleep quality, irritability, poor concentration, low work
productivity, reduced libido, loss of interest and inability to
sleep in the same bedroom with their bed partner. Hence, any
successful form of treatment for OSA should result in an
improvement in the QoL for these patients.
The AHI
The overnight in-hospital polysomnogram has its short-
comings, namely it is resource intensive, including the need
of recording beds, high cost, long waiting lists and intense
labour requirements. Many sleep specialists recognise the
likelihood of a low sleep efficiency due to the first night-effect,
patient anxiety, the restriction of movements from the
abundance of monitoring wirers. Hence, one needs to be
cognisant of the night to night variability in these
cumbersome and uncomfortable sleep tests.
Night-to-night variability may drastically affect the AHI of a
patient being assessed either pre or post-surgery. Chediak et
al.,8reported that 32% of their patients had a difference of
AHI≥10 in two consecutive nights of PSG. Levendowski et al.,10
reported a fairly weak correlation (r = 0.44) between overall
AHI from the two PSG studies conducted approximately 40
days apart with a seven event/hour bias. However,
Stepnowsky et al.,11 did show in 1091 patients that the night-
to-night Pearson correlation coefficients ranged between 0.88
and 0.90 for each pair of nights.
Another consideration would be the use of home-based sleep
studies; e.g., the Watch PAT device versus the in-laboratory
sleep tests.
The third and major confounder, and perhaps the most
common and widely debated factor, is the use of different
definitions of hypopnea in the laboratory systems, and in
addition, the use of different monitoring equipment; e.g., the
use of nasal thermistors versus the use of nasal airflow
pressure sensors. Studies also have reported that the depth of
desaturation varies by equipment manufacturer,31 and the
criteria based on a 4% desaturation may not be the same at
different sleep laboratories. Apnoea definition is fixed, it
refers to a pause in respiration for more than 10 seconds and
is seen in both central sleep apnoea (CSA) and OSA.
Hypopnea is usually defined as reduction in ventilation of at
least 50% that results in a decrease in arterial saturation of
4% or more due to partial airway obstruction. Some sleep
centres define hypopnea as clinically significant when there
is a ≥30% reduction in nasal airflow lasting for 10 seconds or
longer with an associated ≥4% oxygen desaturation and/or if
this results in an arousal or a fragmentation of sleep.
Therefore, it would be prudent to note that there can be huge
test-retest variability from the different available sleep tests in
the market, and this is a confounding factor in assessing
treatment outcomes, purely by using AHI alone. Guidelines
developed to standardise the scoring of sleep and detection of
related events; i.e., accreditation by the American Academy
of Sleep Medicine, appears ineffective in controlling the
inherent variability of OSA when measured by PSG. The
suggestion of multi-night PSG studies is both difficult for
subjects and very expensive. Sleep specialists using solely the
AHI from the PSG for assessing treatment outcomes should
factor in the increased variability, with perhaps high level of
inaccuracy and discordance with the actual patient benefit as
a whole.
SLEEP-GOAL as a Holistic Success Criteria
No sleep specialist has ever had a patient walk into the office
and complained of a raised/elevated AHI. To the patient, the
AHI is a nebulous concept, while other clinical outcomes
measures are more relevant, including subjective sleepiness,
snoring level and level of performance. In addition, most
OSA treatment is aimed at preventing long-term deleterious
effects of the disease; e.g., high blood pressure and
cardiovascular morbidity, yet paradoxically, such
parameters are notably underutilised and relatively invisible
to both medical and surgical studies evaluating treatment
outcomes. When AHI is utilised, sleep specialists may not be
familiar of its short-comings and accept that the archaic
criteria of 50% reduction in AHI and an AHI <20 tends to be
gospel truth. This criterion, based on historical literature was
arbitrarily developed, it did not stratify any patients nor had
any clinical data, parameters or assessments.
Hobson et al., recently showed in a creative study that
differences even in the definition of AHI severity cut-off can
greatly influence reported efficacy of surgery in patients with
OSA.32 For example, let us consider patient A with a pre-
operative AHI of 95 who, after surgery, has a post-operative
PSG of AHI 21; this patient would likely experience
measurable symptomatic and clinical improvement with a
huge decrease in disease burden; in terms of obesity,
hypertension, cardiovascular effects and oxidative stress,
even though this is not defined as a successful surgical
outcome by the numerical old Sher’s AHI criteria, whereas
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122 Med J Malaysia Vol 75 No 2 March 2020
consider another patient B with baseline pre-operative AHI of
35, and who had reduced post-operatively to under 14, this is
considered a successful AHI outcome even though the
likelihood of clinical cardiovascular or QoL impact may be
minimal, as compared to patient A. Intuitively, one would
agree that patient A benefitted significantly more than
patient B, but yet was labelled as a “surgical failure”.
Moreover, not forgetting, that in much of the reported
literature, the pre- and post-surgery sleep test may have been
done in different sleep laboratories, using different definitions
of hypopnea and different sleep diagnostic devices, all of
which can confound reporting.
Hence, employing AHI as the single variable with which to
gauge success of therapy, either medical or surgical, is flawed
and allows it to hold too much weight in the field of sleep
medicine. Other metrics of OSA measurement such as quality
of life, subjective sleepiness, performance, and biological
measures must evolve to play a larger role to study
outcomes.33 Validated subjective measurements, such as QoL
scores, sleepiness scores, and performance testing, better
reflect the patient clinical manifestation than does AHI.
Objective measures such as blood pressure more directly
measure important long-term goals that OSA interventions
aim to treat than does the sole AHI. OSA is more than just
local airway pathology reflected by the number of apnoea
and hypopneas per hour,33 it is the effects on the end-organs.
This SLEEP-GOAL criterion best represents the end-organ
“damage” of the airway obstructions (apnoea and
hypopnea). From our study, we demonstrated that the overall
success rate in our 302 patients, based on the Sher’s criteria
was 66.2%. In order to maintain a success rate as stringent as
the old Sher’s criteria, we set out a target of within 65 to 69%
(approximate) as a reasonable success range for the SLEEP-
GOAL. Based on the list of SLEEP-GOAL clinical outcomes,
and the respective major/minor criteria fulfilment (Table I),
based on a fulfilment of two major and two minor criteria,
the cumulative frequency equivalent to a post-operative
success rate of 69.8%. With a fulfilment of two major and one
minor, the success rate would be 82.2%, and with two major
and three minor fulfilled, the success rate would be 57.9%.
Hence, based on these validated parameters from the list of
SLEEP-GOAL, we propose that any patient who meets the
criteria of at least any of the two major and two minor is
deemed clinical success of that respective intervention.
In addition, we also illustrated that if we had applied the old
Sher’s criteria to these 302 patients, who would have “miss-
classified” many patients as “failures”, those who actually
had good post-intervention results in terms of blood pressure
decrease, BMI and gross weight reduction, and significance
reductions in the duration below 90% oxygen saturations.
Based on the old Sher’s criteria, we would have classified
these as “failures”:
We acknowledge and recognise some short comings of this
paper: As with most multi-centre surgical studies, the surgeon
performing the procedure is slightly different and may
contribute to each individual patient’s success rates. There
are many different surgical techniques that may be employed
by each surgeon; however, this paper’s objective was not to
analyse the technique’s success rates but the type of outcome
measures used. As with most multi-centre studies, the method
and device used for assessing sleep may vary. The device
software may have slightly different definitions of hypopnea
and oxygen desaturation definitions in each country.
However, this is precisely the objective of this study to
illustrate the need on over-reliance of one parameter AHI. As
with most multi-centre studies, language of the
questionnaires could be a confounding factor. Attempts were
made to decrease the confounding by providing translators
where needed. We are aware that not all the enrolled patients
had completed the questionnaires, however, this would
reflect a realistic environment where not all patients are keen
to or would oblige to fill up questionnaires; where this is a
concern, other major criteria from P-GOAL may be used.
CONCLUSION
We recognise that implementing such criteria would
complicate rather than simplify the management of OSA, but
this would be more realistic and holistic, in contrast to the
gross oversimplification of the disease management that
currently occurs by the use of AHI alone. From this study, it
would be fair to conclude that the use of a single AHI
parameter as the only outcome measure for the treatment
intervention for OSA, would be not only misleading but
extremely inadequate.
Treatment intervention need not be surgery, CPAP use,
and/or an oral appliance, it could be a simple weight
loss/dietary program; with the loss of the extra kilograms, the
patient’s BMI or gross weight would decrease, the patient’s
quality of life would improve, blood pressure would be
lowered, sleep parameters and quality improved and the
overall body’s oxidative stress would be lowered. It would be
plausible to state that the paradigm of OSA treatment
outcomes need to be better thought through, redefined and
shifted to a more holistic, comprehensive and realistic
parameter, like the SLEEP-GOAL.
DISCLOSURE
This study was not funded. There are no financial disclosures
and no conflict of interest for all the above authors
ETHICAL APPROVAL
Ethical approval: This article does not contain any studies
with animals performed by any of the authors. All procedures
performed in studies involving human participants were in
accordance with the ethical standards of the institutional
and/or national research committee and with the 1964
Helsinki declaration and its later amendments or comparable
ethical standards. There were no recognisable data or
patient/human profiles within the article.
CONFLICT OF INTEREST
All the authors declare that he/she has no conflict of interest.
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Med J Malaysia Vol 75 No 2 March 2020 123
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