Effects of childhood obstructive sleep apnea with and without daytime sleepiness on behaviors and emotions.

OBJECTIVE: To investigate the relationship between obstructive sleep apnea (OSA) with and without excessive daytime sleepiness (EDS) and behavioral and emotional outcomes in non-obese prepubertal children. METHODS: This was a retrospective analysis of children aged 5-11 years who presented to our unit for assessment of their sleep-related complaints. All children underwent polysomnography (PSG). They also completed the Pediatric Daytime Sleepiness Scale (PDSS) and a sleep diary. OSA was diagnosed if the obstructive apnea-hypopnea index (OAHI) was ≥1 event/hour. EDS was defined as PDSS >15. Behavioral and emotional outcomes were assessed using the Child Behavioral Checklist (CBCL). RESULTS: Data from 391 children (mean age of 8.6 ± 1.7 years; 67 % male) were analyzed. Seventy children did not have OSA or EDS, 137 had OSA, 50 had reported having EDS but without OSA, and 134 children had both OSA and EDS. There were significantly higher CBCL total problems score in the combined group (61 ± 9) compared to the non-OSA/EDS group (54 ± 10), and the OSA-only group (54 ± 10) (p < 0.001). The presence of EDS was significantly associated with higher CBCL T score and higher odds for clinically significant behavioral problems (T score ≥65) after adjusting for age, sex, BMI z-score and average sleep duration (p < 0.001). CONCLUSION: Excessive daytime sleepiness is an important contributory factor associated with suboptimal behavioral and emotional outcomes in children with OSA.

Poor sleep quality and its associated neurocognitive function in children with obesity with or without obstructive sleep apnea.

OBJECTIVE: To evaluate the associations of OSA severity, snoring symptoms, subjective sleep quality, and daytime sleepiness with executive functioning and behaviors in children with obesity. METHODS: This was a cross-sectional study of children aged 8-18 years with obesity and symptoms suggestive of OSA. All participants underwent an overnight polysomnography and completed a set of questionnaires to assess their sleep-related breathing disordered (SRBD) symptoms [Pediatric Sleep Questionnaire (SRBD-PSQ)], sleep quality [Pittsburgh Sleep Quality Index (PSQI)], executive function [Behavior Rating Inventory of Executive Function (BRIEF)], and inattention and hyperactivity symptoms (Conners-3 Parent Short Form). RESULTS: A total of 85 children (62% male, mean age: 13.9 ± 3.0 years) were included in this analysis, of whom 36, 16, and 33 were categorized into the non-OSA (obstructive apnea hypopnea index, OAHI < 1.5/h), mild OSA (OAHI 1.5-5/h), and moderate-severe OSA (OAHI ≥ 5/h) groups, respectively. Of 85 participants, 27 (32%) were classified with poor sleep quality (PSQI composite score ≥ 8). From multiple linear regression analyses, poor sleep quality and sleepiness were both independently associated with higher BRIEF behavioral regulation T-score, metacognition T-score, and global executive composite T-score in the fully adjusted model. In addition, poor sleep quality was also independently associated with higher Conners-3 inattention and executive functioning T-scores, while greater sleepiness was also associated with a higher learning problem T-score. The presence of OSA and snoring were not associated with any cognitive outcomes. CONCLUSIONS: Subjective sleep quality and daytime sleepiness, but not OSA severity and snoring symptoms, were independently associated with executive functioning and behavioral problems in children with obesity.

Effect of surgical intervention for childhood OSA on blood pressure: A randomized controlled study.

OBJECTIVE: To investigate the effect of surgical intervention on 24-h ABP in children with OSA. It was hypothesized that blood pressure would improve following adenotonsillectomy. METHODS: This was a two-centered investigator-blinded randomized controlled trial. Non-obese pre-pubertal children aged 6-11 years with OSA (obstructive apnea-hypopnea index, OAHI >3/h) underwent 24-h ABP monitoring at baseline and 9 months after the randomly assigned intervention, i.e. Early Surgery (ES) or Watchful Waiting (WW). Intention-to-treat analysis was performed. RESULTS: 137 subjects were randomized. Sixty-two (Age: 7.9y ± 1.3, 71% boys) and 47 (Age: 8.5y ± 1.6, 77% boys) participants from the ES and WW groups, respectively completed the study. Changes in ABP parameters were similar in the ES and WW groups (nighttime systolic BP z-scores: +0.03 ± 0.93 vs. -0.06 ± 1.04, p = 0.65; nighttime diastolic BP z-scores: -0.20 ± 0.95 vs. -0.02 ± 1.00, p = 0.35) despite a greater improvement in OSA in the ES group. However, a reduction in nighttime diastolic BP z-score correlated with improvements in OSA severity indexes (r = 0.21-0.22, p < 0.05), and a significant improvement in nighttime diastolic BP z-score [-0.43 ± 1.01, p = 0.027] following surgery was observed in participants with severe preoperative OSA (OAHI ≥10/h). The ES group had a significant increase in body mass index z-score after surgery [+0.27 ± 0.57, p < 0.001], which correlated with the increase in daytime systolic BP z-score (r = 0.2, p < 0.05). CONCLUSION: Surgical treatment did not lead to significant improvements in ABP in OSA children except in those with more severe disease. The improvement in BP was partially masked by the weight gain following surgery. CLINICAL TRIAL REGISTRATION: The trial was registered with the Chinese Clinical Trial Registry (http://www.chictr.org.cn. REGISTRATION NUMBER: ChiCTR-TRC-14004131).

Secular trends of sleep-wake patterns in Hong Kong preschoolers.

OBJECTIVE: To evaluate the secular trends of sleep-wake patterns of Hong Kong preschool children. METHODS: Kindergartens from the four geographical regions of Hong Kong were randomly invited to take part in a sleep survey in 2012 and again in 2018. The parent-completed questionnaire provided information on socioeconomic status (SES), children's, and parental sleep-wake patterns. Secular trends and risk factors associated with short sleep duration in preschoolers were explored. RESULTS: A sample of 5048 preschool children was included in the secular comparison, with 2306 and 2742 from the 2012 and 2018 surveys, respectively. A higher percentage of children in 2018 (41.1% vs 26.7%, p < 0.001) did not achieve the recommended sleep duration. During the survey years, sleep duration decreased by 13 ([95%CI: 18.5 to -8.1]) and 18 min ([95%CI: 23.6 to -12.2]) on weekdays and weekends, respectively. The overall trend of nap decrease was not significant. Sleep onset latency significantly increased on both weekdays (6 min [95%CI: 3.5 to 8.5]) and weekends (7 min [95%CI: 4.7 to 9.9]). Children's sleep duration was positively correlated with parental sleep duration with a correlation coefficient ranging from 0.16 to 0.27 (p < 0.001). CONCLUSIONS: A significant proportion of Hong Kong preschool children did not achieve the recommended amount of sleep. A downward secular trend in sleep duration was observed during the survey period. Public health measures to improve sleep duration in preschool children should be a high priority.

Craniofacial phenotyping by photogrammetry in Chinese prepubertal children with obstructive sleep apnea.

STUDY OBJECTIVES: This study aimed to examine the craniofacial phenotype of Chinese prepubertal children with and without obstructive sleep apnea (OSA) using a quantitative photographic analysis technique and to develop a prediction model for OSA diagnosis based on the photogrammetric data. Potential ethnic differences in the association between OSA and photogrammetric data between Chinese and Caucasian children were also examined. METHODS: This was a cross-sectional study. Chinese children aged 5-12 years old, suspected to have OSA were recruited from our sleep clinic. Frontal and side photos were taken for craniofacial phenotyping by photogrammetry. Polysomnography was performed and participants were divided into three groups: non-OSA (obstructive apnea hypopnea index (OAHI) < 1/h), mild OSA (OAHI between 1/h and 5/h), and moderate-to-severe (MS) OSA (OAHI ≥ 5/h). Prediction models were built from 70% of training data using logistic regression and evaluated on the remaining 30% of test data for receiver operating characteristic (ROC) curve construction. RESULTS: This study included 90 participants (mean age: 8.2 ± 1.6 years, 67 males). Non-OSA, mild OSA, and MS OSA groups included 32, 31, and 27 participants, respectively. There were significant trends for an increasing maxillary-mandibular relationship angle (p = .002) and a decreasing anterior mandibular height to whole face length ratio (p < .001) with increasing OSA severity. A prediction model built with clinical measurements and the two photogrammetric features yielded an area under the ROC curve (AUC) of 0.81 (95% C.I.: 0.64-0.96). CONCLUSIONS: Craniofacial features obtained by photogrammetry are significantly different between OSA groups in prepubertal children. Increased maxillary-mandibular relationship angle is an OSA feature found in both Asian and Caucasian children.

Validation of the Sonographic Measurement of Lateral Parapharyngeal Wall Thickness in Childhood Obstructive Sleep Apnea.

Background: Lateral parapharyngeal wall (LPW) thickness is a potentially useful anatomical marker of childhood obstructive sleep apnea (OSA). Measuring LPW thickness by ultrasonography (USG) is technically feasible but its use in children has not been validated. Therefore, this study aimed to assess the intra- and inter-operator reliability of the sonographic measurements of LPW thickness in children and to assess its validity against magnetic resonance imaging (MRI) measurements. Methods: Prepubertal children aged 6-11 years suspected to suffer from OSA were recruited. Repeated measurements of LPW thickness by USG were conducted to evaluate the intra- and inter-operator reliability, examined by intraclass correlation coefficient (ICC). LPW thickness was measured as the distance between the internal carotid artery and the echogenic surface of the pharynx in an oblique coronal plane by USG. LPW thickness was measured by MRI at the retropalatal level. The agreement between the LPW thickness measured by USG and MRI was assessed by ICC and Bland-Altman plot. Results: Thirty-four children (mean age: 8.66 ± 1.61, 26 male) were recruited. The intra- and inter-operator reliability of the LPW thickness by USG was good (ICC = 0.84 and 0.82, respectively). The agreement between the USG-measured and MRI-measured LPW thickness was moderate (ICC = 0.72). he Bland-Altman plot demonstrated a mean difference of 0.061 cm and a 95% limit of agreement from 0.91 to 1.12 cm. Conclusion: In this study, we demonstrated that ultrasonography is a valid and reliable method to assess LPW thickness in children. This study was supported by the Direct Grant for Research from the Research Committee of the Chinese University of Hong Kong (Project no. 2020.073).

The impact of sleep-corrected social jetlag on mental health, behavioral problems, and daytime sleepiness in adolescents.

STUDY OBJECTIVES: This study aimed to examine the effect of sleep-corrected social jetlag (SJLsc) on mental health, behavioral problems, and daytime sleepiness in adolescents. METHODS: This was a cross-sectional study which included 4787 adolescents (Mean age: 14.83±1.6y, 56.0% girls) recruited from 15 secondary schools in Hong Kong. SJLsc was defined as the absolute difference between sleep-corrected midsleep on weekdays and weekends, at which the sleep debt has been considered. It was classified into three groups: low-level ("LSJLsc", <1h), mid-level ("MSJLsc", ≥1h and <2h), and high-level of SJLsc ("HSJLsc", ≥2h). Adolescents' mental health, behavioral problems and daytime sleepiness were measured by the General Health Questionnaire (GHQ-12), the Strengths and Difficulties Questionnaire (SDQ) and the Pediatric Daytime Sleepiness Scale (PDSS). Logistic regression analysis and restricted cubic spline regression (RCS) analysis were applied with consideration of confounders including age, gender, puberty and sleep problems. RESULTS: Nearly half (46.9%) of adolescents had SJLsc for at least 1 h. Greater SJLsc was associated with more behavioral difficulties (MSJLsc: OR: 1.20, p = 0.03; HSJLsc: OR: 1.34, p = 0.02) when controlling for age, sex, puberty, chronotype, insomnia, and time in bed. There was a dose-response relationship in which higher SJLsc had an increased risk of conduct problems and hyperactivity, while only high-level SJLsc was associated with a peer relationship problem. In RCS analysis, SJLsc was associated with a higher likelihood of behavioral difficulties (p = 0.03) but not poor mental health or daytime sleepiness. CONCLUSIONS: Sleep-corrected social jetlag was a unique risk factor for behavioral problems in adolescents. Our findings highlighted the need for interventions to promote healthy sleep-wake patterns in school adolescents.

Blood pressure and childhood obstructive sleep apnea: A systematic review and meta-analysis.

Obstructive sleep apnea (OSA) is an established risk factor for high blood pressure (BP) in adults. However, it remains unclear whether the same association could be found in children and adolescents. Therefore, we conducted a systematic review and meta-analysis of observational studies to evaluate the associations between childhood OSA and BP outcomes. The review protocol was registered in PROSPERO (CRD42021225683). We performed a systematic literature search to identify relevant cross-sectional and longitudinal studies up to July 6, 2021. Of the 4902 identified articles, a total of 12 cross-sectional studies and 2 cohort studies were included in the final analyses. In the cross-sectional analyses, the mean systolic BP (SBP) were significantly higher in children with mild or moderate-to-severe OSA compared to the healthy controls, and these effects were more pronounced during the nighttime. In prospective studies, moderate-to-severe childhood OSA was associated with a risk of elevated SBP in adulthood (Mean difference = 4.02 mm Hg, 95% CI = 1.32 to 6.72). Taken together, our results suggest that moderate-to-severe childhood OSA is associated with a higher risk of adverse SBP outcomes. Early detection and treatment of OSA may promote cardiovascular health in children and adolescents and possibly in future adulthood.

Monthly Motivational Interview Counseling and Nicotine Replacement Therapy for Smoking Parents of Pediatric Patients: A Randomized Controlled Trial.

Background: Parental smoking is the dominant source of passive smoke exposure in the pediatric population. The current randomized controlled trial (RCT) study aimed to evaluate the effectiveness of a multi-component smoking reduction intervention in parental smoking reduction and children's environmental tobacco smoke exposure reduction in clinical settings. Methods: A single-blinded, 6-month randomized controlled trial recruited smoking parents (N = 210) of children who attended the pediatric wards or clinics at the Prince of Wales Hospital. Participants allocated to the intervention group (n = 105) received monthly motivational interviews on smoking reduction with emphasis on health hazards related to children's passive smoke exposure, 8-week nicotine replacement therapy, and referral to smoking cessation service if the parents preferred. The control group (n = 105) received simple verbal advice on smoking cessation. Primary outcomes were parental urine cotinine validated and self-reported ≥50% smoking reduction rates at 6 months. Results: Smoking parents in the intervention group had significantly more biochemically validated ≥50% smoking reduction than the control: 27.1 vs. 10.0% (OR = 3.34, 95% CI: 1.16-9.62, P = 0.02). The rate of self-reported ≥50% smoking reduction was also significantly higher in the intervention group than the control: 51.9 vs. 20.2% (OR = 4.40, 95% CI: 2.38-8.12, P < 0.001). For secondary outcomes, the rate of parental self-reported smoking cessation was higher in the intervention arm: 10.5 vs. 1.0% (OR = 12.17, 95% CI: 1.54-96.07, P < 0.001), however, no differences were detected in biochemically validated cessation and changes in children's passive smoke exposure between the groups. Conclusion: Monthly smoking reduction counseling together with nicotine replacement therapy is more effective than simple verbal cessation advice in the smoking reduction for parents of pediatric patients. However, this study did not demonstrate differences in smoking cessation or reduction in children's passive smoke exposure with a 6-month follow-up. Achievement of a smoke-free environment remains challenging. Trial Registration: Clinicaltrials.gov, identifier: NCT03879889.

Sleep Complaints Among School Children.

Sleep complaints are common among children. These include both night-time and daytime symptoms, such as trouble falling asleep, problems in maintaining sleep, snoring, and unusual events during sleep and daytime functioning impairment. However, sleep complaints in children are often overlooked and undertreated in clinical practice. Untreated sleep problems may further impact on children's development and will persist into adulthood in some cases. This review summarizes the common sleep complaints and disorders in school children, and provides an overview of the epidemiology, clinical features, consequences, and treatment of the sleep problems.

Reduced tongue mobility: an unrecognized risk factor of childhood obstructive sleep apnea.

STUDY OBJECTIVES: Childhood obstructive sleep apnea (OSA) is an important and prevalent disease. A short lingual frenulum is a risk factor for OSA, but whether tongue mobility also plays a role in OSA etiology remains unknown. This study aimed to examine tongue mobility in children with and without OSA. We hypothesized that reduced tongue mobility was associated with OSA. We also evaluated the relationship between tongue mobility and craniofacial profile. METHODS: This was a cross-sectional case-control study. Prepubertal Chinese children aged 5-12 years, suspected to have OSA were recruited from our sleep disorder clinic. All subjects underwent overnight polysomnography. The lingual frenulum was evaluated based on tongue mobility and free tongue length. Craniofacial measurements were assessed by lateral cephalometry. RESULTS: Eighty-two subjects (mean age: 8.32 ± 1.70 years, 57 males) were recruited. The mean tongue mobility was 58.2 (±19)% and 67.4 (±15)% (p = 0.019) in subjects with and without OSA, respectively. Tongue mobility was inversely correlated with OAHI (r = -0.218, p = 0.049). In multivariate logistic regression, low tongue mobility was independently associated with a higher risk of OSA after adjustment for age, sex, body mass index z-score, presence of large tonsils and turbinates, and nocturnal oral breathing (odds ratio = 3.65, 95% CI = 1.22 to 11.8). Tongue mobility was found to correlate with the cranial base angle (Ba-S-N) (r = 0.262, p = 0.018), which determines the relative position of the mandible. CONCLUSIONS: In prepubertal children, reduced tongue mobility is associated with the occurrence and severity of OSA. Assessing tongue mobility is recommended in childhood OSA management.

Parental Knowledge, Attitude, and Practice on Tobacco Use, Smoking Cessation, and Children's Environmental Tobacco Smoke Exposure.

Background: Environmental tobacco smoke (ETS) exposure in children ranks one of the major public health problems in our time. Poor parental knowledge, attitude, and practice (KAP) on ETS often contribute to worse exposure of the kids. Thus, we aimed to document parental KAP regarding tobacco use, smoking cessation and children's ETS exposure, and to analyse how knowledge and attitude relate to practice. Methods: Self-administered KAP questionnaires were distributed to smoking parents recruited from the pediatric unit at the Prince of Wales Hospital, which provides pediatric service to a population of 1.2 million in Hong Kong. The 60-item questionnaire had a range of 0-38 for knowledge, 0-44 for attitude, and 0-40 for practice. Descriptive analyses were performed for KAP response, regression analyses were performed for the exploration of associations and identification of predictive indicators. Results: 145 smoking parents (mean age: 38.0 ± 6.7 yrs.; male: 85.5%) were included. Less than half (39.3%) of them reported a smoke-free policy at home. Among those parents who had private cars, less than half (45.2%) of them had smoke-free policy in their car that they never smoked in the car. Only 25.5% of the participants correctly answered ≥70% of the knowledge questions, and 11.8 % of the participants gave favorable responses to ≥70% of the attitude questions. The total knowledge and the total attitudes score were positively associated (r = 0.49, 95% CI: 0.35-0.79, p < 0.001), yet they were only modestly correlated with parental practice on children's ETS exposure. By multivariate regressions, potential predictive factors for more favorable parental KAP included higher household income, lower parental nicotine dependence level and breastfeeding practice. Conclusions: Parental KAP related to tobacco use and children's ETS exposure needs improvement to address the significant gap between recommended and actual practice. The weak association between knowledge and practice suggested that parental education alone is not adequate to combat ETS exposure in children.

The trajectories and associations of eveningness and insomnia with daytime sleepiness, depression and suicidal ideation in adolescents: A 3-year longitudinal study.

BACKGROUND: Eveningness and insomnia are highly comorbid and closely related to psychopathology in adolescents. We aimed to prospectively investigate the trajectories and associations of eveningness and insomnia with daytime functioning, depression and suicidal risk in adolescents. METHODS: A 3-year longitudinal study was conducted among 414 Chinese adolescents. The associations of eveningness and insomnia with daytime functioning, depression and suicidal ideation were analyzed using logistic regressions. RESULTS: The prevalence rates of eveningness were similar at baseline and follow-up (19.3% vs 22.5%; p = 0.27), while the prevalence of insomnia increased at follow-up (29.2% vs 40.8%; p < 0.001). Among those eveningness adolescents (n=80) at baseline, 46.2% remained as stable evening-type at follow-up, and among those insomnia adolescents (n=121) at baseline, 64.5% had persistent insomnia at follow-up. Logistic regressions showed that stable, incident, and resolved eveningness were associated with excessive daytime sleepiness (EDS) at follow-up, while only persistent and incident insomnia increased the risk of EDS. Persistent and incident insomnia, as well as stable eveningness were independently associated with depression at follow-up. Persistent and incident insomnia, but not eveningness, were associated with suicidal ideation. LIMITATIONS: The outcome assessments were based on self-reported questionnaires and the sample size is modest. CONCLUSIONS: Persistent eveningness and insomnia are significantly associated with greater risks of EDS and depression in adolescents, while both persistent and incident insomnia, but not eveningness, increased the risk of suicidal ideation. These findings underscore the importance of addressing sleep and circadian factors in the management of adolescent mood and daytime functioning.

Cardiovascular risks of children with primary snoring: A 5-year follow-up study.

BACKGROUND AND OBJECTIVE: This study aimed to investigate if childhood primary snoring (PS) was associated with adverse cardiovascular outcomes at 5-year follow-up. METHODS: This was a prospective matched cohort study. Subjects were recruited from a hospital-based cohort established from years 2006 to 2012 and they were aged 6-18 years at baseline. Each subject with PS was gender, age and BMI z-score matched with a control who had normal sleep study (obstructive apnoea-hypopnoea index [OAHI] < 1/h) and without habitual snoring (<3 nights/week) at baseline. All subjects underwent measurements of flow-mediated dilation (FMD) and carotid intima-media thickness (cIMT) and sleep study at baseline and follow-up visits. Twenty-four hour ambulatory blood pressure (ABP) was also recorded at follow-up. RESULTS: Fifty-five case-control pairs were recruited and the length of follow-up was 5.1 ± 1.3 years. At follow-up visit, subjects with PS at baseline had significantly lower FMD (-0.34% [-0.59 to -0.10]), greater cIMT (+0.01 mm [+0.001 to +0.013]), higher wake systolic blood pressure (SBP) (+2.6 mm Hg [+0.02 to +5.1]), sleep SBP (+3.0 mm Hg [+0.3 to +5.6]), sleep diastolic blood pressure (+2.2 mm Hg [+0.04 to +4.4]) and sleep mean arterial pressure (+2.2 mm Hg [+0.1 to +4.2]) compared to matched controls in the fully adjusted model for variables including change in OAHI and parental history of cardiovascular diseases. CONCLUSION: Childhood PS is associated with poorer endothelial function, greater cIMT and higher ABP at 5-year follow-up irrespective of change in obstructive sleep apnoea severity.

Intermediate phenotypes of childhood obstructive sleep apnea.

An intermediate phenotype of a disease is a trait in the path of pathogenesis from genetic predisposition to disease manifestation. Identifying intermediate phenotypes with high heritability is helpful in delineating the genetics of a disorder. In this study, we aimed to examine various traits with regards to obesity, cardiovascular risk and upper airway structure to identify potential intermediate phenotypes of childhood obstructive sleep apnea (OSA). Children aged between 6 and 18 years and their parents and siblings were recruited. All subjects underwent anthropometric measurements, cardiovascular risk assessment, sonographic measurement of lateral parapharyngeal wall (LPW) thickness, X-ray cephalometry and overnight polysomnography. A total of 34 phenotypes were examined. One hundred and one families consisting of 127 children (46 overweight) and 198 adults (84 overweight) were recruited. Heritability of obstructive apnea-hypopnea index (OAHI) was significant in overweight (h2  = 0.54) but not normal-weight individuals (h2  = 0.12). LPW thickness (h2  = 0.68) and resting blood pressure (h2  = 0.36 and 0.43 for systolic blood pressure [SBP] and diastolic blood pressure [DBP], respectively) were significantly heritable and associated with OAHI. Moreover, these traits were found to have shared genetic variance with OAHI in the overweight subgroup. Hyoid bone position also had significant heritability (h2  = 0.55) and association with OAHI but genetic correlation with OSA severity was not demonstrated. These findings suggest that LPW thickness and resting blood pressure are possible intermediate phenotypes of OSA independent of body mass index, especially in overweight patients. Identifying genes relevant to these phenotypes may help to elucidate the genetic susceptibility of OSA.

Childhood OSA is an independent determinant of blood pressure in adulthood: longitudinal follow-up study.

BACKGROUND: Current literature supports cross-sectional association between childhood obstructive sleep apnoea (OSA) and elevated blood pressure (BP). However, long-term cardiovascular outcomes in children with OSA remain unexplored. OBJECTIVE: To evaluate the associations of childhood OSA with BP parameters in a prospective 10 year follow-up study. METHODS: Participants were recruited from a cohort established for our previous OSA epidemiological study. They were invited to undergo clinical examination, overnight polysomnography and 24-hour ambulatory BP monitoring. Multivariate linear regression was used to assess the associations of baseline childhood OSA with BP outcomes at follow-up. Multivariable log-binomial regression was used with inverse probability weighting to assess the adjusted associations of childhood OSA with hypertension and non-dipping of nocturnal BP in adulthood. RESULTS: 243 participants (59% male) attended the follow-up visit. The mean age was 9.8 (SD ±1.8) and 20.2 (SD ±1.9) years at baseline and follow-up respectively, with a mean follow-up duration of 10.4 (SD ±1.1) years. Childhood moderate-to-severe OSA was associated with higher nocturnal systolic blood pressure (SBP) (difference from normal controls: 6.5 mm Hg, 95% CI 2.9 to 10.1) and reduced nocturnal dipping of SBP (-4.1%, 95% CI -6.3% to 1.8%) at follow-up, adjusted for age, sex, Body Mass Index and height at baseline, regardless of the presence of OSA at follow-up. Childhood moderate-to-severe OSA was also associated with higher risk of hypertension (relative risk (RR) 2.5, 95% CI 1.2 to 5.3) and non-dipping of nocturnal SBP (RR 1.3, 95% CI 1.0 to 1.7) at follow-up. CONCLUSION: Childhood OSA was found to be an independent risk factor for adverse BP outcomes in adulthood.

Familial Aggregation and Heritability of Obstructive Sleep Apnea Using Children Probands.

STUDY OBJECTIVES: Previous studies suggest the presence of familial aggregation of obstructive sleep apnea (OSA) in adults. However, similar data on childhood OSA are limited. This family study aimed to investigate the heritability and familial aggregation of childhood OSA and to examine whether significant differences existed between patients of normal weight and overweight. METHODS: Children aged 6 to 18 years were recruited as probands either from attendants to sleep clinic (with habitual snoring) or the community (without habitual snoring). Parents and siblings of the probands were also invited to participate. All participants underwent nocturnal sleep study. RESULTS: A total of 229 probands took part, of whom 33 had moderate to severe OSA, 70 had mild disease, and 126 had no OSA. A total of 412 relatives were also recruited. Although the overall heritability of obstructive apnea-hypopnea index (OAHI) was not significant (h² ± SE = 0.03 ± 0.09, P = .37), it was significant in overweight individuals on subgroup analysis (h² ± SE = 0.43 ± 0.24, P = .032). Significant interaction effect of overweight was demonstrated in both heritability and familial aggregation analyses. Bivariate genetic analysis found that the genetic correlation between OAHI and body mass index in overweight individuals (ρg ± SE = 0.63 ± 0.18) was significantly different from both 0 (P = .005) and 1 (P = .025). CONCLUSIONS: The differential results of heritability and familial aggregation of OSA in normal weight and overweight subgroups substantiated the recommendation of separating childhood OSA into normal weight and overweight subtypes. In the overweight subgroup, there may be obesity-independent components involved in the genetic variance of OAHI, although a significant proportion of the genetic variance is shared with obesity.

Potential Anatomic Markers of Obstructive Sleep Apnea in Prepubertal Children.

STUDY OBJECTIVES: Adenotonsillar hypertrophy is the major cause of obstructive sleep apnea (OSA) in prepubertal children, but children without enlarged lymphoid tissues may still suffer from OSA. This study aimed to identify other potential anatomic features associated with childhood OSA. METHODS: This prospective study took place between January 2010 and April 2014. Prepubertal children suspected to have OSA, aged 6 to 11 years, were recruited. They underwent anthropometric measurements, nocturnal polysomnography, tonsil size evaluation, x-ray cephalometry, and sonographic measurement of lateral parapharyngeal wall (LPW) thickness. Linear regression analyses were used to test for the association between anatomic measurements and OSA severity. Logistic regression analyses were used to identify potential anatomic markers for different cutoffs (obstructive apneahypopnea index (OAHI) ≥ 1 and ≥ 5 events/h) for OSA. RESULTS: Forty-seven children with OSA (20 with moderate to severe disease) and 43 children for the control group were recruited. Sonographic measurement of LPW thickness and position of hyoid bone taken from x-ray cephalometry were risk factors associated with OSA. Linear regression analyses found that these two phenotypes were associated with OAHI. Multivariate models adjusted for age, sex, body mass index, z score, and tonsil size revealed that lower position of hyoid bone was independently associated with higher risk for OSA, whereas both lower position of hyoid bone and greater LPW thickness were associated with higher OAHI and also a higher risk for moderate to severe OSA. CONCLUSIONS: Position of hyoid bone and LPW thickness are anatomical markers of childhood OSA independent of obesity and tonsil size. Screening tools may include cephalometry and sonographic measurement of LPW to allow better delineation of OSA risk.

Short Sleep Duration Is Weakly Associated with Carotid Intima-Media Thickness in Adolescents.

OBJECTIVE: To investigate the relationship between sleep duration and carotid intima-media thickness (CIMT) in adolescents. We hypothesized that short sleep duration was associated with an increased CIMT. STUDY DESIGN: This was a cross-sectional study. Healthy participants aged 10-18 years were recruited from a school-based cohort established to examine the prevalence of obstructive sleep apnea in Hong Kong. All participants completed a prospective 7-day sleep diary, underwent anthropometric measurements, overnight polysomnography, and CIMT assessment. Overweight participants or those with an obstructive apnea hypopnea index of ≥5 were excluded from analysis. Regression analysis was used to assess the association between CIMT and sleep duration and other possible correlates. RESULTS: One hundred forty-two participants completed the assessments. Male participants tended to have shorter sleep duration than females (P = .012). There were no differences in age, body mass index, Tanner developmental stage, or parental history of hypertension between groups of different sleep durations. There was a weak but significant association between short sleep duration and CIMT (r = -0.273; P < .001). CONCLUSION: Sleep duration was found to have a weakly negative association with CIMT. Further research is needed to determine whether adult adverse cardiovascular events may originate in childhood owing to short sleep duration.

Effects of resistance training on cardiovascular health in non-obese active adolescents.

AIM: To determine the benefits of a 10-wk resistance training programme on cardiovascular health in non-obese and active adolescents. METHODS: This is a pragmatic randomised controlled intervention. The study was carried out in a Hong Kong Government secondary school. Thirty-eight lean and active boys and girls were randomised to either the resistance training group or the control group. Students in the resistance training group received in-school 10-wk supervised resistance training twice per week, with each session lasting 70 min. Main outcome measures taken before and after training included brachial endothelial dependent flow-mediated dilation, body composition, fasting serum lipids, fasting glucose and insulin, high sensitive C-reactive protein, 24-h ambulatory blood pressure and aerobic fitness. RESULTS: The only training related change was in endothelial dependent flow-mediated dilation which increased from 8.5% to 9.8%. A main effect of time and an interaction (P < 0.005) indicated that this improvement was a result of the 10-wk resistance training. Main effects for time (P < 0.05) in a number of anthropometric, metabolic and vascular variables were noted; however, there were no significant interactions indicating the change was more likely an outcome of normal growth and development as opposed to a training effect. CONCLUSION: Ten weeks of resistance training in school appears to have some vascular benefit in active, lean children.