Incidence and remission of sleep-disordered breathing and related symptoms in 6- to 17-year old children--the Tucson Children's Assessment of Sleep Apnea Study.

Abstract

To determine the incidence and remission of sleep-disordered breathing in adolescent children.
A total of 319 children completed 2 home polysomnograms approximately 5 years apart. Sleep-disordered breathing (SDB) was determined to be present if a child had a respiratory disturbance index>or=1 event per hour associated with >or=3% oxygen desaturation. Subjective symptoms such as witnessed apnea, excessive daytime sleepiness, difficulty initiating and maintaining sleep, and habitual loud snoring were considered present if they occurred frequently or almost always. Body mass index percentiles were calculated with childhood growth charts from the Centers for Disease Control and Prevention adjusted for sex and age.
The mean age at assessment was 8.5 years at baseline and 13.7 years at follow-up, respectively. Incident SDB was more common in boys (odds ratio [OR]=3.93, P=.008, confidence interval [CI]=1.41-10.90). Children with prevalent SDB were more likely to be boys (OR=2.48, P=.006) and had a greater increase in body mass index percentile change (OR 1.01, P=.034). Children with prevalent SDB also had 3.41 greater odds for development of obesity from baseline to follow-up in comparison with children with prevalent NoSDB.
Adolescent boys are more likely to have persistent and incident SDB than girls. Children with prevalent SDB are more likely to have development of obesity. These risks are similar to those observed in adults.

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Incidence and Remission of Sleep Disordered Breathing and
Related Symptoms in 6-17 Year Old Children-the Tucson
Children's Assessment of Sleep Apnea Study (TuCASA)
James L. Goodwin, PhD1,2,3, Monica M. Vasquez, MPH2,3, Graciela E. Silva, PhD, MPH4, and
Stuart F. Quan, MD1,2,3,5
1College of Medicine, University of Arizona, Tucson, AZ
2Arizona Respiratory Center, University of Arizona, Tucson, AZ
3Mel and Enid Zuckerman College of Public Health, University of Arizona, Tucson, AZ
4College of Nursing & Health Innovation, Arizona State University, Phoenix, AZ
5Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston,
MA
Abstract
Objective—To determine the incidence and remission of sleep disordered breathing in adolescent
children.
Study design—319 children completed two home polysomnograms approximately 5 years apart.
Sleep disordered breathing (SDB) was determined to be present if a child had a respiratory
disturbance index ≥ 1 event per hour associated with a ≥3% oxygen desaturation. Subjective
symptoms such as witnessed apnea, excessive daytime sleepiness, difficulty initiating and
maintaining sleep, and habitual loud snoring were considered present if they occurred frequently or
almost always. BMI percentiles were calculated using CDC childhood growth charts adjusted for
sex and age.
Results—The mean age at assessment was 8.5 years at Baseline and 13.7 years at Follow-up
respectively. Incident SDB was more common in boys (OR=3.93, p=.008, CI= 1.41-10.90). Children
with Prevalent SDB were more likely to be boys (OR=2.48, p=.006) and had a greater increase in
BMI percentile change (OR 1.01, p=.034). Children with Prevalent SDB also had 3.41 greater odds
of developing obesity from Baseline to Follow-up in comparison with children with Prevalent
NoSDB.
Conclusions—Adolescent boys are more likely to have persistent and incident SDB than girls.
Children with prevalent SDB are more likely to have developed obesity. These risks are similar to
those observed in adults.
Correspondence: James L. Goodwin, PhD, 1501 N. Campbell AHSC 245030, The University of Arizona, Tucson, AZ 85724-5030,
Phone: 520-621-5001, FAX: 520-626-6970, jamieg@arc.arizona.edu.
Reprint request author : James L. Goodwin
Edited by RW and WFB
The authors declare no conflicts of interest.
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Published in final edited form as:
J Pediatr. 2010 July ; 157(1): 57–61. doi:10.1016/j.jpeds.2010.01.033.
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Sleep disordered breathing (SDB) in children has been associated with a number of
physiological, neurocognitive, and behavioral problems.1-4 Moreover, there is increasing
evidence that sleep disordered breathing has an important adverse impact on a child's physical
and cognitive health and social development.1, 5-7
Although there are several studies specifying the prevalence of snoring and other sleep related
problems in children,8-10 11, 12 there is little evidence documenting the incidence and remission
of symptoms associated with sleep disorders in children, such as witnessed apnea, excessive
daytime sleepiness, habitual snoring, and insomnia.13-15 Furthermore, there are no data to date
indicating the incidence and remission rates of SDB in a large sample of children using
polysomnography as well as identifying factors associated with incidence or remission. This
gap in the research literature was highlighted in an extensive recent review of the epidemiology
of pediatric obstructive sleep apnea (OSA).16 The Tucson Children's Assessment of Sleep
Apnea (TuCASA) study is a longitudinal cohort study designed to investigate the physiologic,
anatomic and behavioral correlates of SDB and to document their changes with development.
In this analysis, we present data on the incidence, remission, and persistence of SDB and related
symptoms.
Methods
Details of the TuCASA study design have been published previously.10, 17 Briefly, Hispanic
and Caucasian children ages 6 to 11 years were recruited to undergo unattended home
polysomnography and perform a neurocognitive assessment. Subjects were recruited through
the Tucson Unified School District (TUSD), a very large district with a substantial elementary
school population. Parents were asked to complete a short screening questionnaire and to
provide their contact information if they were willing to allow study personnel to contact them
to determine if their child was eligible for the study. A total of 7,055 screening questionnaires
were sent home with children in a “notes home” folder. Of these, 2,327 (33%) were returned.
Recruitment information was supplied on 52% of the returned questionnaires from which we
selected children, based on pre-established inclusion and exclusion criteria, to undergo
polysomnography. An unattended home polysomnogram was scheduled as soon as possible
after recruitment. From 1999-2003, 503 children aged 6-11 years completed home
polysomnograms (Baseline). Approximately five years later (Follow-up, mean 4.7 years), 348
children participated in the second phase of the study; 319 children had home visits where
acceptable in-home polysomnography was completed. On both occasions, all of the families
completed sleep screening, sleep habits, and morning questionnaires. The TuCASA study was
approved by the University of Arizona Institutional Review Board (IRB) as well as the Tucson
Unified School District (TUSD) Research Committee.
The methods for obtaining data have been previously described17. In brief, a two-person, mixed
sex team arrived at the home approximately one hour prior to the child's normal bedtime. Prior
to performing any study procedures, parents gave informed consent and the child gave assent
to the study using language appropriate IRB approved forms. Each child's height, weight, neck
circumference, and blood pressure were measured. A parent was asked to complete a
comprehensive Sleep Habits Questionnaire (SHQ) that inquired about their child's sleep history
and sleep characteristics.
A single, unattended overnight polysomnogram was obtained using the Compumedics PS-2
system (Abbotsford, Victoria, Australia). The following signals were acquired as part of the
TuCASA montage: C3/A2 and C4/A1 electroencephalogram, right and left electrooculogram,
a bipolar submental electromyogram, thoracic and abdominal displacement (inductive
plethysmography band), airflow (nasal/oral thermister), nasal pressure cannula, finger pulse
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oximetry, ECG (single bipolar lead), snoring microphone, body position (Hg gauge sensor),
and ambient light.
Scoring of sleep was performed by a single registered polysomnographic technologist using
Rechtschaffen and Kales criteria.18 Arousals were identified using criteria published by the
American Academy of Sleep Medicine.19 Apneas were scored if the amplitude (peak to trough)
of the airflow signal using the thermistor decreased below at least 25% of the amplitude of
baseline breathing (identified during a period of regular breathing with stable oxygen levels),
if this change lasted for more than 6 seconds or 2 breath cycles. Hypopneas were designated
if the amplitude of any respiratory signal decreased below (approximately) 70% of the
amplitude of baseline and if the thermister signal did not meet the criterion for apnea. Central
events were marked if no displacement was noted on both the chest and abdominal inductance
channels. However, central events that occurred after movement were not included. Otherwise,
events were scored as obstructive. After full scoring, analysis software was used to link each
event to data from the oxygen saturation and EEG channels. The Respiratory Disturbance Index
(RDI) was defined as the number of respiratory events (apneas and hypopneas) per hour of
total sleep time. For this analysis, a 3% oxygen desaturation was required for an event to be
counted in the total RDI. In our primary analyses, we considered a child to have SDB if their
RDI was greater than or equal to 1 event per hour of total sleep time. Use of this definition is
supported by previous evidence that a RDI of one, based on events with a 3% oxygen
desaturation, is clinically significant.12, 20, 21 We also explored the impact of using definitions
of RDI with cutpoints up to 10 events per hour.
Witnessed Apnea (WITAP) was defined as stopping breathing, struggling to breathe, or having
to shake the child awake while sleeping. Excessive Daytime Sleepiness (EDS) was defined as
being sleepy in the daytime, falling asleep at school or while watching television. Snoring (SN)
was present if the parent reported their child snored loudly. Insomnia (DIMS) was present if
the child currently experienced trouble falling asleep, staying asleep, or waking too early. The
symptom was defined as present if the parent reported it occurred “frequently” or “almost
always”.
Body mass index (BMI) percentiles were calculated using U.S. Centers for Disease Control
childhood growth charts adjusted for sex and age.22 Children were categorized as obese if they
exceeded the 95th percentile of BMI for their age, sex, and ethnicity. Variables pertaining to
incidence and remission of SDB were defined as follows: IncidentSDB denotes no SDB at
Baseline and SDB at Follow-up; RemissionSDB denotes SDB at Baseline and no SDB at
Follow-up; PersistentSDB denotes SDB at Baseline and at Follow-up; PersistentNoSDB
denotes no SDB at Baseline and no SDB at Follow-up; PrevalentSDB denotes Persistent SDB
group + Incident SDBgroup; PrevalentNoSDB denotes RemissionSDB group +
PersistentNoSDB group.
Data Analysis
The Student t-test and the 2 sample test of proportion were used to compare differences in
characteristics at baseline and follow-up. Potential predictors of incident and remissive SDB
were also investigated. These variables included change in neck circumference, BMI
percentile, sleep efficiency, and total sleep time. Additional variables included parent reported
witnessed apnea, snoring, excessive daytime sleepiness, insomnia, sex, and ethnicity. Logistic
regression was used to determine predictors of incidence, remission, and persistence or absence
of SDB as defined above.
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Results
The mean age at first assessment was 8.5 years (range: 6-12), and mean age at second
assessment was 13.7 years (range: 10-18). The mean time between assessments was 4.6 years
(range: 2.9-7.3). There were 50.4% males and 49.6% females at the time of initial enrollment;
this sex ratio remained approximately the same at the second assessment. Ethnicity was 58.5%
Caucasian and 41.5% Hispanic.
Table I shows the characteristics of the cohort at Baseline and Follow-up. Of note was that the
prevalence of both SN and WITAP, as well as polysomnographically determined SDB,
decreased from Baseline to Follow-up. SN declined from 15.0% to 9.7% and WITAP decreased
from 5.2% to 2.2%. Moreover, the percentage of children with a RDI ≥1 fell from 23.9% to
15.3%. In contrast, the rate of obesity increased from 12.9% to 19.2%.
The incidence and remission rates for SDB and symptoms of sleep disturbances are displayed
in Table II. Incidence rates for key symptoms of sleep disturbance were: SN 4.1%, EDS 11.8%,
WITAP 0.9%, and DIMS 16.6%. Remission rates were SN 60.3%, EDS 63.8%, WITAP 84.0%,
and DIMS 47.8%. For polysomnographically determined SDB, the incidence rate was 10.0%
and the remission rate was 70.8%.
Using a logistic regression model and empirically testing each predictor variable, children with
IncidentSDB were compared with children with Prevalent NoSDB. We also compared children
with RemissionSDB to those children who had PrevalentSDB. Boys were more likely to
develop SDB (OR=3.93, p=.008, CI = 1.41-10.90).
In addition to exploring incident and remissive cases alone, we explored predictors for the
combination of incident and persistent cases (Prevalent SDB compared with Prevalent
NoSDB). Children with PrevalentSDB were more likely to be boys (OR=2.48, p=.006, CI
(1.29-4.76)) and had a greater increase in BMI percentile change (OR 1.01, p=.034, 1.01-1.03)
(Figure). Children with PrevalentSDB also had a 3.41 greater odds (p<.001, CI: 1.76-6.61) of
developing obesity from Baseline to Follow-up in comparison with children with Prevalent
NoSDB. Parent reported symptoms or other measured physiological variables on the night of
the PSG were not predictive of future incident SDB or remission of SDB.
We examined the number of incident, remission and persistent cases from Baseline to Follow-
up for higher cutpoints of RDI, such as 2, 5, and 10 events per hour. Unfortunately, the number
of cases were too few to do any meaningful analysis with only 13, 3, and 1 case respectively
for each of the above cutpoints.
Seventeen children had tonsillectomies between the time of their first and second
polysomnographic evaluation. Eight children had PersistentNoSDB and two children had
PersistentSDB, resulting in no change to SDB classification. Following tonsillectomy, 3 of the
17 children had incident SDB, and 4 had remission of SDB. Subsequent analyses showed that
having a tonsillectomy had no influence on our conclusions.
Discussion
In this analysis, we found that in children between the ages of 6 and 11 years, the incidence of
parent reported sleep symptoms over the ensuing 5 years is relatively low. Moreover, except
for symptoms consistent with insomnia, most symptoms of sleep disorders remit. In addition,
we found that not all children with polysomnographically determined SDB remit and that some
children develop SDB during this interval. Male sex and obesity appear to be the most important
risk factors for prevalent SDB in this age group. These data indicate that SDB does not
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necessarily resolve with the onset of adolescence in children and risks for SDB in adolescence
are similar to those observed in adults.
The highest incidence rates we observed were for insomnia-related symptoms (DIMS) and
excessive daytime sleepiness. These findings are consistent with the physiologic sleep phase
delay occurring in adolescents and the potentially hectic social environment in which they live.
In this age group, factors such as enhanced autonomy, and familial, educational and
psychosocial stresses may contribute to poor sleep hygiene.23, 24 Interestingly, remission rates
for EDS were higher than remission rates for DIMS. The explanation for these differences is
not clear. However, the factors contributing to EDS and DIMS in 6-11 year old children are
not the same as in 12-18 year old adolescents. Thus, whereas SDB may be an important
contributing cause of EDS in younger children, insufficient sleep may be more relevant in the
older age group. Similarly, the aforementioned social environment not only contributes to the
higher incidence of DIMS, but also to a relatively low remission rate.
In contrast to DIMS and EDS, the incidence rates for snoring and witnessed apnea were much
lower. It is difficult to contrast our findings with respect to snoring with prior studies because
of differences in the age of the cohorts and length of follow-up. Nevertheless, our snoring
incidence rate of 4.1% over an approximate 5 year interval is comparable with the 4.5% rate
over a 3 year interval reported by Anuntaseree et al and the 4.3% rate observed by Chervin et
al over a 4 year interval.7, 25 Incidence and remission rates for the symptom of witnessed apnea
have not been previously reported. However, the prevalence rate observed at follow-up in the
current study (2.0%) is similar to the findings of Sánchez-Armengol et al in a cohort of 12-16
year old children (3%),26 but higher than observed by Joo et al in a group of 15-18 year old
Korean high school students. 27 It is possible that the older age of the cohort in the latter study
accounts for this difference.
We observed a 10% incidence rate and a 70.8% remission rate for polysomnographically
confirmed SDB in our study. There have been few prior studies documenting the incidence
and remission rates of SDB in children, with most occurring in small cohorts recruited from
clinical sources. Marcus et al initially studied a small group of children and found that 2 of 20
with primary snoring had evidence of SDB on polysomnography 1-3 years later.14 Similarly,
Topol and Brooks found 1 of 13 children had evidence of SDB 3 years later.15 In contrast,
Anuntaseree et al found 5 new cases of SDB in 61 children (9.1%) with habitual snoring 3
years previously.25 Our study extends these limited observations to a much larger cohort
studied after a long duration spanning the time period between preadolescence to adolescence.
Our results indicate that there is a small but significant number of preadolescent children who
will develop SDB as they become adolescents. Moreover, although it is generally expected
that both snoring, and consequently SDB, should resolve over time in preadolescents in parallel
with regression of tonsillar and adenoidal tissue, our finding that the remission rate is only
70.8% indicates that a considerable number of children with SDB will not spontaneously
resolve. Given the increasing data that SDB in children adversely impacts neurocognition and
behavior, and may increase the risk of hypertension and obesity, our results provide additional
evidence that active intervention to treat SDB in preadolescents is indicated.
We observed that prevalence of SDB or no SDB was associated with sex and increasing weight.
Boys as well as those children who had excessive weight gain were more likely to have SDB
at the time of the 2nd TuCASA examination. In adults, SDB also is more common in males
and those who are obese. Thus, our findings support the hypothesis that factors important in
the development of SDB in adolescents are similar to those operative in adults. Given the
increasing prevalence of obesity in both children and adults in the general population, it is
likely that SDB will be a more common occurrence in children, especially adolescents.
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