Treatment Outcomes of Adenotonsillectomy for Children with Obstructive Sleep Apnea: A Prospective Longitudinal Study
Treatment Outcomes of Adenotonsillectomy for Children with Obstructive Sleep Apnea: A Prospective Longitudinal Study
Yu-Shu Huang 2 3 4
Christian Guilleminault 2
DBiol 1 2 4
Li-Ang Lee 0 2
Cheng-Hui Lin 2 6
Fan-Ming Hwang 2 5
0 Department of Otolaryngology and Sleep Center, Chang Gung Memorial Hospital and College of Medicine , Taoyuan , Taiwan
1 Stanford University Sleep Medicine Division , Stanford, CA , USA
2 AT Outcomes of Pediatric OSA-Huang et al
3 Department of Child Psychiatry and Sleep Center, Chang Gung Memorial Hospital and College of Medicine , Taoyuan , Taiwan
4 Department of Clinical Psychology College of Medicine, FU JEN Catholic University , Taipei , Taiwan
5 Department of Education, National Chia-Yi University , Chiayi , Taiwan
6 Department of Cranio-Facial Center and Sleep Center, Chang Gung Memorial Hospital and College of Medicine , Taoyuan , Taiwan
Objective: To evaluate the efficacy of adenotonsillectomy (AT) in the treatment of children with obstructive sleep apnea (OSA) in a 3-y prospective, longitudinal study with analysis of risk factors of recurrence of OSA. Study Design: An investigation of children (6 to 12 y old) with OSA documented at entry and followed posttreatment at 6, 12, 24, and 36 mo with examination, questionnaires, and polysomnography. Multivariate generalized linear modeling and hierarchical linear models analysis were used to determine contributors to suboptimal long-term resolution of OSA, and Generalized Linear Models were used for analysis of risk factors of recurrence. Results: Of the 135 children, 88 terminated the study at 36 months post-AT. These 88 children (boys = 72, mean age = 8.9 ± 2.7 yersus boys 8.9 ± 2.04 y, girls: 8.8 ± 2.07 y; body mass index [BMI] = 19.5 ± 4.6 kg/m2) had a preoperative mean apnea-hypopnea index (AHI0) of 13.54 ± 7.23 and a mean postoperative AHI at 6 mo (AHI6) of 3.47 ± 8.41 events/h (with AHI6 > 1 = 53.4% of 88 children). A progressive increase in AHI was noted with a mean AHI36 = 6.48 ± 5.57 events/h and AHI36 > 1 = 68% of the studied group. Change in AHI was associated with changes in the OSA-18 questionnaire. The residual pediatric OSA after AT was significantly associated with BMI, AHI, enuresis, and allergic rhinitis before surgery. From 6 to 36 mo after AT, recurrence of pediatric OSA was significantly associated with enuresis, age (for the 24- to 36-mo period), postsurgery AHI6 (severity), and the rate of change in BMI and body weight. Conclusions: Adenotonsillectomy leads to significant improvement in apnea-hypopnea index, though generally with incomplete resolution, but a worsening over time was observed in 68% of our cases.
Obstructive sleep apnea (OSA) syndrome is a highly
prevalent condition in children and characterized by snoring,
witnessed apnea, unrefreshing sleep, and excessive daytime
sleepiness.1,2 Children with OSA experience recurrent periods
of elevated upper airway resistance during sleep due to
partial or complete upper airway obstruction, which results in
snoring, episodic oxyhemoglobin desaturation, hypercapnia,
and repeated arousals.3,4 The respiratory disturbance of
recurrent hypoxia-reoxygenation episodes during the night is
associated with an increased risk of suboptimal growth, poor sleep
quality, neurocognitive dysfunction, behavioral problems,
overweight status, and cardiovascular disease in childhood.5-8
The prevalence of OSA is approximately 2-3% in children,9,10
and current studies have evaluated the influence of OSA on
various associated morbidities5-8,11 and tried to identify the
factors predicting poor treatment outcome.12
The choice of therapy for OSA is predicated on the etiology,
severity, and individual history of the increased upper airway
resistance. The timely diagnosis and appropriate treatment
of OSA is especially important, because untreated OSA can
account for markedly increased health care costs.13-15
Adenotonsillar hypertrophy is considered an important factor in the
development of OSA in otherwise healthy children.
Adenotonsillectomy (AT) is recommended as the first line of treatment
for childhood OSA by the American Academy of Pediatrics,1
and the effectiveness of AT in the treatment of children with
OSA has been confirmed by several studies.15-17 However,
some studies examining the efficacy and outcomes of AT in
pediatric OSA showed incomplete resolution of OSA after
surgery.12-17 For example, nonobese children with severe OSA
and chronic asthma were found to be at higher risk of residual
OSA in a recent multicenter retrospective study.12 In addition,
few studies have evaluated the overall long-term efficacy of AT
in the treatment of children with OSA. Thus, this 3-y
prospective, longitudinal study aimed to delineate factors contributing
to potential post-AT OSA through careful examination of
demographic and pre- and post-AT polysomnography (PSG)
information. In our geographical location, the mean age for AT
at the time of the study was approximately 8 y, and such age
for surgery was based on two factors: usual recommendations
made by ear, nose, and throat (ENT) surgeons when AT was
considered, and reluctance of parents in our culture to have
their children undergo nonemergency surgery.
Starting in August 2007, children between the ages of 6 and
12 y with signs and symptoms of a sleep disturbance, including
snoring, mouth breathing, and witnessed breath holding, lasting
for at least 3 mo, were evaluated prospectively using a
standardized history and physical examination, neurocognitive and
psychological testing, and PSG in the sleep center of Chang
Gung Memorial Hospital (CGMH). The CGMH sleep clinic is
a multidisciplinary clinic with expertise in the management of
pediatric sleep apnea and is the only accredited pediatric sleep
laboratory in Taiwan.
The inclusion criteria for subjects, based on PSG, were
an obstructive apnea-hypopnea index (AHI, the number of
apnea and hypopnea events per hour of sleep) greater than one
event/h or a respiratory disturbance index (RDI) of more than
five events/h with clinical symptoms. Both patients and parents
agreed to participate in this longitudinal study and were willing
to sign informed consent.
Exclusion criteria for the children were previous AT,
craniofacial abnormalities, neuromuscular disease, or other significant
medical, psychiatric, or genetic disorders, and obesity (obesity
was defined based on Taiwan general public health tables, taking
into consideration age and body mass index (BMI) in kg/m2).18
This prospective study was approved by the institutional
review board of CGMH, and the caregivers (parents) signed
informed consent before their children were enrolled for study.
All subjects underwent a routine medical history and
physical examination by an otolaryngologist, a craniofacial surgeon,
a pediatrician, and a child psychiatrist for assessment of
A standardized datasheet for patient demographic data,
including age, sex, height, weight and all systemic
comorbidities, was checked by child psychiatrists.
The ENT examination was performed by an
otolaryngologist and a craniofacial surgeon. Tonsillar size was graded as
) small tonsils confined to the tonsillar pillars; (
tonsils that extended just outside the pillars; (
) tonsils that
extended outside the pillars but did not meet at the midline; (
large tonsils that met at the midline.19 Adenoid tissue was
examined with a lateral x-ray film of the neck or a flexible fiberoptic
endoscope. The amount of obstruction was categorized into four
grades (grade 0 = 0-25%, grade 1 = 25-50%, grade 2 = 50-75%,
and grade 3 = 75-100%). Allergic rhinitis was confirmed by a
specific immunoglobulin E (IgE) blood test (ImmunoCAP®
100; Phadia, Uppsala, Sweden), and duration and persistence of
symptoms and comorbidities according to the Allergic Rhinitis
and its Impact on Asthma (ARIA) classification.
Questionnaire evaluation: Parents completed the
obstructive sleep disorder questionnaire (OSA-18).20,21 It is a
subjective questionnaire that contains 18 items and covers quality of
life. The items are divided into six domains: sleep disturbance,
physical suffering, emotional distress, daytime problems,
caregiver concerns, and total quality of life.20,21
During the evaluation period, children underwent other
mental and cognitive tests not presented here.
Once the clinical evaluation was complete, a standard
overnight PSG with simultaneous video recording was used for
on 14 May 2018
each subject in the hospital sleep laboratory preoperatively and
6 mo (AHI6), 12 mo (AHI12), 24 mo (AHI24), and 36 mo (AHI36)
after AT. All children were instructed to discontinue any
medication (or PSG was scheduled at least 7 days after
discontinuation of medications prescribed for acute health problems prior
to PSG). A family member was required to be present for all
nocturnal PSG recordings. Sleep and wake were scored using
the international criteria of Rechtschaffen and Kales22 with
identification of stages 3 and 4, and identification of the onset
of abnormal behavior to a specific sleep stage. EEG arousal
was defined according to the guidelines of the American Sleep
Disorders Association.23 Abnormal breathing events during
sleep were analyzed according to the definitions of an apnea
and hypopnea as outlined by the American Academy of Sleep
Medicine (AASM),23 and the definition of flow limitation with
abnormal increase in respiratory effort leading to arousals as
outlined by Lin and Guilleminault.24 Based on these
definitions, the AHI and a respiratory disturbance index (RDI, the
number of apneas, hypopneas, and respiratory effort-related
arousals per hour of sleep) were calculated. Periodic limb
movement (PLM) was defined according to the AASM scoring
rules,23 with a PLM index (PLMI) > 5 per hour being
considered abnormal. PLMs associated with breathing events were
not scored, and only those independent of apnea/hypopnea
were considered. Abnormal behavior on video was noted when
present. PSG scoring was performed by a technician blind to
the clinical status of the child.
All children were given antileucotriene medication for 6 mo
We followed the children posttreatment at 6, 12, 24, and
36 mo with the same examination, questionnaires, and PSG.
Descriptive statistics were performed. Considering the
missing data in longitudinal studies and the evolution of AT
over time, multivariate generalized linear model (GLM) and
hierarchical linear models (HLM) analyses were used to
determine contributors to residual sleep apnea at various time points
post-AT. GLM statistics were used to analyze the risk factors
for OSA recurrence after AT looking at the entire follow-up
period. We used HLM analyses to investigate the changes
during the different follow-up points (AT6,12,24,36): because there
were different numbers of subjects at each follow-up-point, a
two-level model was used. We analyzed fixed effects in level
one, and random effects in level two. The coefficient of level
one (fixed effects) was the intraclass correlation (ICC) which
was, in our model, the proportion of group level variance from
the total variance.
During the study period, 135 pediatric OSA subjects who
underwent AT were enrolled. Eighty-eight children (64.6%)
completed all preoperative and postoperative evaluations and
were included in the analysis. The dropout rate was 17.8% in
the first year, 28.9% in the second year, and 35.4% in third year,
indicating the reluctance of parents to participate in long-term
follow-up. The mean age at the time of screening was 8.9 ±
2.7 y. Boys were predominant in this sample (n = 72, 81.8%
mean age 8.9 ± 2.04). The mean AHI before AT (AHI0), was
13.53 ± 7.23 events/h and the mean BMI was
19.54 ± 4.64 kg/m2. The BMI-z score revealed
that our subjects were not obese. We compared
the characteristics of subjects that completed
the study and those that did not, and found there
was no significant difference between these two
groups (Tables 1 and 2).
A comparison of PSG data before and after
AT showed that the baseline AHI0 (13.53 ±
7.23 events/h; median = 6.85, range 1.2 to
49.4 events/h) had improved significantly at all
post-AT yearly time points (AHI12 P < 0.001,
AHI24 P < 0.001, AHI36 P = 0.004, respectively).
Rapid eye movement (REM) sleep also showed
a significant increase at all post-AT yearly time
points (P = 0.04, 0.016, 0.003, respectively), as
did the percentage of slow wave sleep (P = 0.03,
0.02, 0.006, respectively). Median AHI also
was significantly improved at all post-AT
yearly time points (Tables 3 and 4).
Overall, these data indicate the positive
results of surgery but do not represent the real
postsurgical evolution of the AHI over time.
Using a multivariate Generalized Linear Model
(GLM) analysis we found a significant
improvement in the AHI (mean AHI0 = 13.54 to mean
AHI6 = 3.47 events/h) during “period 1”
(preAT-AHI0-to 6 mo post-AT-AHI6-). The success
rate of AT in this study at 6- mo postsurgery is
therefore 46.6%. The remaining 53.4% of the
children had an AHI6 greater than one event/h
During period 2 (6 to 36 mo post-AT) there
was an AHI elevation beginning at the 6-mo
time point: from mean AHI6 = 3.47 to mean
AHI36 = 6.48 events/h (range: AHI6 = 0 to
35.5 events/h to AHI36 = 0 to 42.3 events/h).
Though all values were significantly less
than the baseline AHI (AHI0), the mean AHI
showed a significant increase from 6 to 36 mo posturgery
(Tables 3 and 4 and Figure 1). Using GLM analysis, we
found persistence of a significant difference between
presurgery and postsurgery PSG data, but this effect varied between
different time sequences: With HLM analysis and the
twolevel model calculations, the coefficient in level one (fixed
effects) showed again that the value of the AHI was
significantly reduced during the period (AHI0 to AHI6), and that
the significant positive gains covered not only AHI but also
apnea index (AI), mean oxygen saturation, sleep latency,
wake after sleep onset (WASO), and percentage of REM
sleep. But in period 2, the proportion of the AHI was
significantly increased: from 6 mo posttreatment to later time points
(up to AHI36). This AHI rebound starting 6 mo postsurgery
was associated with a worsening of nocturnal sleep (WASO,
sleep latency, and sleep efficiency).
We divided the post-AT patients into two groups. Group 1
(the successful group, n = 41) had an AHI6 < 1 at AT+6 mo. The
Number of subjects
Mean age at time of screening (y old)
Number of males
BMI (kg/m2) (mean ± SD) at entry
BMI z score at entry
BMI, body mass index; SD, standard deviation.
aDiagnosed according to criteria of Diagnostic and Statistical Manual of Mental Disorders,
Fourth Edition. bConfirmed and diagnosed by pediatricians. ENT, ear, nose and throat; ADHD,
attention deficit hyperactivity disorder; PLM, periodic limb movement.
analysis of this subgroup, considered as initially fully treated,
revealed that the recurrence rate was 35.3% after AT+12 mo,
50% after AT+24 mo, and 66.7% after AT+36 mo. Group 2
(the nonsuccessful group, n = 47) had an AHI6 > 1 at AT+6 mo
and also showed a progressive increase in the residual AHI
at +36 mo. Overall, when considering worsening and
recurrence, 68% of the children followed had an abnormal AHI
and abnormal sleep at AT+36 mo. The mean AHI36 was
6.48 ± 5.57events/h.
Determination of risk factors for OSA recurrence after AT
was based on GLM of repeated measure analysis: AHI6 was
significantly associated with BMI, body weight, AHI, and
the presence of enuresis and allergic rhinitis before surgery:
the risk factor of residual pediatric OSA 6 mo after AT was
significantly related to BMI and body weight, severity of
pediatric OSA, enuresis and rhinitis before surgery. The analyses
performed in period 2 (from post-AT+6 mo to +36 mo) showed
that the recurrence of pediatric OSA was significantly
associated with age, persistence of enuresis, the AHI post-AT+6 mo,
and a fast and abnormal increase of BMI and body weight (from
Figure 1—Change of apnea-hypopnea index (AHI) after
adenotonsillectomy using Multivariate generalized linear modeling (GLM)
and the hierarchical linear model (HLM); the straight thin line indicates the
significant linear increase. Period 1 (from before AT -AHI0- to 6 months
post AT surgery-AHI6): results showed a significant improvement in AHI
(from a mean AHI0 = 13.54 to a mean AHI6 = 3.47 events/h). Period 2
(from 6 mo postsurgery-AHI6 to 36 mo postsurgery -AHI36): the mean AHI
significantly increased between 6 mo postsurgery to 36 mo postsurgery
(mean AHI6 = 3.47 to mean AHI36 = 6.48 events/h). This increase was
associated with recurrence in 68% of subjects followed for 36 mo
aP < 0.05. bP < 0.01. cP < 0.001. AHI, apnea-hypopnea index; AI, apnea index; BMI, body mass index; Bw, body weight; mean SaO2, mean oxygen saturation;
PSG, polysomonography; SD, standard deviation; WASO, wake after sleep onset.
post-AT+6 mo to +12 mo, from +12 mo to +24 mo, and from
+24 mo to +36 mo) (Table 5).
Six months after AT, the OSA-18 analyses showed
significant improvement in the items of sleep disturbance (mean:
4.06 ± 1.52 to 2.40 ± 1.22), physical suffering (mean:
3.82 ± 2.02 to 2.79 ± 1.92), daytime problems (mean:
4.12 ± 1.98 to 3.33 ± 2.03), caregiver concerns (mean:
4.44 ± 1.78 to 3.01 ± 1.91) and total quality of life (mean:
5.12 ± 2.08 to 6.01 ± 2.95) (higher scores indicated greater
severity, except the item of total quality of life, which was the
reverse). However, the items of sleep disturbance, daytime
problems, and caregiver concerns worsened again at +36 mo
post-AT. The results of the sleep questionnaire were similar to
the results of the PSG.
The limitations of this study include: (
) a somewhat small
sample size, ending with 88 children and a male predominance;
the dropout rate was 36% with only 88 subjects completing the
36-mo follow-up; (
) age (6 to 12 y) was taken into
consideration when AT would usually be performed in Taiwan;
) because of our institutional review board, this was not a
randomized controlled trial; (
) the lack of obese children (a
deliberate choice); and (
) the fact that craniofacial structure
imaging data (i.e., three-dimensional computed tomography)
Generalized linear model (GLM ) with normal distribution and log link function. The risk-factors for OSA recurrence after AT based on GLM of repeated measure analysis. BMI_0: means
BMI before AT. BMI_D: means the change (increasing) of BMI from post-AT 6 months to 12 months; the change (increasing) of BMI from post AT 12 months to 24 months; the change
(increasing) of BMI from post-AT 24 months to 36 months. Est., estimate; S.E., standard error; Wald Sta, Wald statistics.
was not performed on every child. Although a 1-y follow-up
study of sleep disordered breathing with AT25 has discussed the
recurrence issue, our study, to the best of our knowledge, is
the first prospective 3-y longitudinal study of pediatric OSA
after AT. Also, the long-term follow-up of these patients was
performed in the same hospital sleep center using the same
recording techniques and PSG scoring criteria. Clinical
evaluation was a systematic evaluation that was based on criteria
established prior to the beginning of the study, and repeated
psychiatric and neurocognitive testing was administered by the
AT is the treatment of choice for pediatric OSA and our
results showed significant improvements post-AT. However,
incomplete resolution of pediatric OSA was noted in many
of our children. Our results show that post-AT OSA does not
spontaneously remit, and although the effect size was relatively
small (66.7% of subjects), AHI did worsen over time, even if
surgery was successful at 6 months posttreatment. A recent study
has reported some mechanisms by which this worsening may
occur.12 Asthma was not a predictive factor for post-AT OSA in
our study group, but our rate of asthma was low at the outset.
This difference may be related to differing rates of asthma and
triggers, differences in OSA phenotype or subtype compared to
other study populations, or overall adequacy of treatment and
lung function during the study period. In this study, the
predictive factors of residual pediatric OSA after AT-HI6 were BMI
and body weight, severity of pediatric OSA, and enuresis and
rhinitis before surgery. The recurrence and persistence of
pediatric OSA was associated with enuresis, age (post-AT+24 mo
to post-AT+36 mo), AT-AHI6 (the severity of residual pediatric
OSA after AT) and the change (with a fast increase) in BMI
and body weight (from post-AT-AHI6 to AHI12, from
post-ATAHI12 to AHI24, and from post-AT-AHI24 to AHI36). Increases
in BMI and body weight are common post-AT.17 Also, there is
reluctance in our own pediatric field to perform AT with young
children, and surgical treatment acceptance varies depending
on culture and the pediatrician’s education. At times, surgery
may be delayed, and this is related to the issues that delay the
treatment of OSA. Therefore, education will be an important
issue to physicians in the future. Moreover, the GLM analysis
in our study showed that age was a risk factor for recurrence of
OSA after AT. Age not only has an effect on oral-facial growth,
with 60% of the adult face already formed by 4 y of age,26 but it
may favor incomplete surgical results and secondary worsening
posttreatment, as age at the time of surgery was a significant
variable predicting incomplete resolution of pediatric OSA.
Our study supports the need to perform AT at an earlier age
than it is often done in our culture and some other cultures.27
Independent of age, AT overall improved OSA, but even if it
appeared successful initially, as demonstrated by recordings
at 6 mo postsurgery, recurrence of abnormal breathing within
1 to 3 y is important. Overall, 68% of children treated with
adenotonsillectomy presented a mean AHI of 6.48 events/h.
This polysomnographic finding is associated with a subjective
and objective demonstration of poor sleep, and a
demonstration of the worsening of symptoms associated with attention
and daytime hyperactivity.
Our study outlines some risk factors, such as severe pediatric
OSA, obesity, and a large increase in BMI after AT, rhinitis,
enuresis, and older age for recurrence of OSA, but we do
not claim to have identified all of the risk factors. Finally, an
obvious conclusion of our work is that children in whom OSA
is diagnosed require long-term follow-up.
The authors thank professor Fan-Ming Hwang and Po-Yu
Huang, PhD, for help with statistical analysis, and Shannon
Sullivan, MD, for her editing of the manuscript.
This was not an industry supported study. This research
was supported by Chang Gung Memorial Hospital: CMRPG
470011. The authors have indicated no financial conflicts of
AT Outcomes of Pediatric OSA—Huang et al
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