Applicability of the Global Lung Function Initiative prediction equations in Hong Kong Chinese children.

BACKGROUND AND OBJECTIVE: This study aimed to assess the applicability of the Global Lung Function Initiative (GLI) prediction equations for spirometry in Hong Kong children and to develop prediction equations based on the Generalized Additive Models for Location, Scale, and Shape (GAMLSS) modeling. METHODS: Healthy Chinese children and adolescents aged 6-17 years old were recruited from randomly selected schools to undergo spirometry. The measurements were transformed to z-score according to the GLI-2012 equations for South East (SE) Asians and the GLI-2022 global race-neutral equations. Prediction equations for spirometric indices were developed with GAMLSS modeling to identify predictors. RESULTS: A total of 886 children (477 boys) with a mean age of 12.5 years (standard deviation [SD] 3.3 years) were included. By the GLI-2012 SE Asian equations, positive mean z-scores were observed in forced expiratory volume in 1 s (FEV1 ) (boys: 0.138 ± SD 0.828; girls: 0.206 ± 0.823) and forced vital capacity (FVC) (boys: 0.160 ± 0.930; girls: 0.310 ± 0.895) in both sexes. Negative mean z-scores were observed in FEV1 /FVC ratio (boys: -0.018 ± 0.998; girls: -0.223 ± 0.897). In contrast, negative mean z-scores in FEV1 and FVC, and positive mean z-scores in FEV1 /FVC were observed when adopting the GLI-2022 race-neutral equations. The mean z-scores were all within the range of ±0.5. By GAMLSS models, age and height were significant predictors for all four spirometric indices, while weight was an additional predictor for FVC and FEV1 . CONCLUSION: Our study provided data supporting the applicability of the GLI prediction equations in Hong Kong Chinese children. The GLI-2012 equations may underestimate FEV1 and FVC, while the GLI-2022 equations may overestimate the parameters, but the differences lie within the physiological limits. By GAMLSS modeling, weight was an additional predictor for FVC and FEV1 .

Pulmonary function in patients with transfusion-dependent thalassemia and its associations with iron overload.

In patients with transfusion-dependent thalassemia (TDT), pulmonary function impairment has been reported but data are conflicting. Moreover, it remains unclear whether pulmonary dysfunction is associated with iron overload. This study aimed to evaluate the pulmonary function in patients with TDT and to investigate the associations between pulmonary dysfunction and iron overload. It was a retrospective observational study. 101 patients with TDT were recruited for lung function tests. The most recent ferritin levels (pmol/L) and the magnetic resonance imaging (MRI) measurements of the myocardial and liver iron status, as measured by heart and liver T2* relaxation time (millisecond, ms) respectively, were retrieved from the computerized medical records. Only data within 12 months from the lung function measurement were included in the analysis. The serum ferritin, and the cardiac and liver T2* relaxation time were the surrogate indexes of body iron content. The threshold of abnormality in lung function was defined as under 80% of the predicted value. 101 subjects were recruited with a mean age of 25.1 years (standard deviation (SD) 7.9 years). Thirty-eight (38%) and five (5%) demonstrated restrictive and obstructive lung function deficits, respectively. A weak correlation of FVC %Predicted and TLC %Predicted with MRI myocardial T2* relaxation time (rho = 0.32, p = 0.03 and rho = 0.33, p = 0.03 respectively) was observed. By logistic regression, MRI cardiac T2* relaxation time was negatively associated with restrictive lung function deficit (B - 0.06; SE 0.03; Odds ratio 0.94; 95% confidence interval (CI) 0.89-0.99; p = 0.023) after adjusting for age, sex and body mass index. Restrictive pulmonary function deficit was commonly observed in patients with TDT, and the severity potentially correlates with myocardial iron content. Monitoring of lung function in this group of patients, particularly for those with iron overload, is important.

Level of urinary catecholamine in children with Sleep Disordered Breathing: A systematic review and meta-analysis.

OBJECTIVE: To compare the levels of different urinary catecholamines amongst paediatric patients with and without sleep-disordered breathing (SDB). METHODS: Literature searches were conducted on PubMed and EMBASE until 25/06/2022. Inclusion criteria were original human studies, English language, paediatric subjects diagnosed with SDB/obstructive sleep apnoea (OSA). The quality of studies was assessed by the Newcastle-Ottawa Quality Assessment (NOSGEN). The registered number of this study on the International Prospective Register of Systematic Reviews (PROSPERO) is CRD42022332939. The main outcome measured was standardised mean difference (SMD) of urinary catecholamine between subjects with and without SDB, between those with and without OSA, and also between subjects with mild OSA and those with moderate/ severe OSA. Sensitivity analyses were performed to avoid bias. RESULTS: 9 studies (8 cross-sectional and 1 cohort study) with a total of 838 subjects, were included in the quantitative analysis. Urine level of noradrenaline was higher in patients with SDB, which included primary snoring (PS), when compared to controls: SMD = 0.86 (95%CI=0.32-1.41; I2=85%, P=0.002). The levels of urinary noradrenaline and adrenaline were higher in children with OSA when compared to controls: SMD = 1.45 (95%CI=0.91-2.00; I2=75%, P < 0.001); SMD = 1.84 (0.00-3.67; I2=97%, P=0.05). Urine level of noradrenaline was higher in subjects with moderate/severe OSA compared to the mild OSA: SMD = 0.55 (95%CI=0.10-1.00; I2=0%, P=0.02). Urinary dopamine was not associated with SDB regardless of severity. CONCLUSIONS: Urinary noradrenaline was higher in all patients with SDB. Subjects with OSA, a more severe form of SDB, had higher urine levels of noradrenaline and adrenaline. Hence, noradrenaline and adrenaline may be markers of sympathetic overtone in patients with SDB and could potentially act as surrogate markers for SDB complications. Further studies are needed to assess this association.

Inferior endothelial function improved following optimisation of asthma control in children.

Association between asthma control and cardiovascular disease (CVD) remains highly plausible as the two are related to chronic systemic inflammation. Children with physician-diagnosed asthma and matched healthy controls underwent endothelial function assessment. Repeat measurements were performed in uncontrolled asthmatics after initiation or up-titration of inhaled corticosteroids (ICS), compared to those with well-controlled asthma without ICS therapy. We found that children with uncontrolled asthma had inferior endothelial function compared to matched healthy controls. Enhancement in endothelial function, lung function and symptom control was observed in uncontrolled asthmatics after initiation or up-titration of inhaled corticosteroids (ICS). These results provided further evidence of a likely relationship between asthma control and cardiovascular health.

Natural History of REM-OSA in Children and Its Associations with Adverse Blood Pressure Outcomes: A Longitudinal Follow-Up Study.

PURPOSE: Most respiratory events in childhood obstructive sleep apnea (OSA) take place during rapid-eye-movement (REM) sleep. This study aimed to describe the characteristics and natural history of childhood REM-OSA and to evaluate the associations between OSA subtypes and blood pressure (BP) outcomes. PARTICIPANTS AND METHODS: This was a prospective 10-year follow-up study of a cohort established for a childhood OSA epidemiologic study. All subjects from the original cohort were invited to undergo a polysomnography (PSG) and 24-hour ambulatory blood pressure (ABP) monitoring. REM-OSA was defined with a ratio of obstructive apnea hypopnea index (OAHI) during REM sleep (OAHIREM) to OAHI during non-REM sleep (OAHINREM) ≥ 2. Natural history was observed and linear mixed models were used to assess the associations between OSA subtypes and BP outcomes. RESULTS: A total of 610 participants from baseline were included to study the epidemiology of REM-OSA in childhood. Among children with OSA, 65% had REM-OSA. At 10-year follow-up, 234 were included in the analysis. REM-OSA was more common at both baseline (58/92, 63%) and 10-year follow-up (34/58, 59%). For those with REM-OSA at baseline and persistent OSA at follow-up, the majority (72%) remained to have REM-OSA. Compared to those without OSA, subjects with REM-OSA had significantly higher nocturnal SBP (mean difference 2.19 mmHg, 95% confidence interval (CI): 0.12, 4.26; p = 0.039) and DBP (mean difference 1.58 mmHg, 95% confidence interval (CI): 0.11, 3.04; p = 0.035), and less nocturnal SBP dipping (mean difference -1.84%, 95% CI: -3.25, -0.43; p = 0.011), after adjusting for potential confounders. This significant association between REM-OSA and nocturnal SBP dipping was observed at baseline visit only. CONCLUSION: REM-OSA was found to be a stable phenotype through childhood to young adulthood, and REM-OSA was associated with higher nocturnal BP and a lesser degree of nocturnal SBP dipping in children.

Effect of surgical intervention for mild childhood obstructive sleep apnoea on attention and behavioural outcomes: A randomized controlled study.

BACKGROUND AND OBJECTIVE: We evaluated inattention and behavioural outcomes following surgery versus watchful waiting (WW) in school-aged children with mild obstructive sleep apnoea (OSA). METHODS: A prospective randomized controlled study was performed in pre-pubertal children aged 6-11 years with polysomnography (PSG)-confirmed mild OSA. They were assigned randomly to early surgical intervention (ES) or WW. The surgical intervention consisting of tonsillectomy with or without adenoidectomy and turbinate reduction was carried out within 4-6 weeks after randomization. Both groups underwent PSG, attention and behavioural assessment and review by an otorhinolaryngologist at baseline and 9-month follow-up. The primary outcome was omission T score from Conners' continuous performance test (CPT). Secondary outcomes were parent-reported behaviours, quality of life, symptoms and PSG parameters. RESULTS: A total of 114 participants were randomized. Data of 35 subjects from the ES and 36 from the WW group were available for final analysis. No significant treatment effect could be found in all CPT parameters and behavioural outcomes. Nevertheless, significantly greater reductions were seen in PSG parameters (obstructive apnoea-hypopnoea index [-1.4 ± 2.0 cf. +0.3 ± 4.1/h, p = 0.038] and arousal index [-1.3 ± 4.4 cf. +1.4 ± 4.5/h, p = 0.013]) and OSA-18 total symptom score (-17.3 ± 19.7 cf. -3.6 ± 14.1, p = 0.001) in the ES group. Subjects who underwent surgery also had significantly greater weight gain (+3.3 ± 2.1 cf. +2.2 ± 1.5 kg, p = 0.014) and increase in systolic blood pressure (+5.1 ± 12.4 cf. -1.2 ± 8.7 mm Hg, p = 0.016). CONCLUSION: Despite improvements in PSG parameters and parent-reported symptoms, surgical treatment did not lead to parallel improvements in objective attention measures in school-aged children with mild OSA.

Sleep duration in preschool children and impact of screen time.

OBJECTIVES: To evaluate sleep duration in a representative sample of preschoolers and examine the relationships between screen time and use of different electronic media devices with sleep duration and social jetlag. METHODS: 2903 preschoolers were included. Parent-completed questionnaire provided information on socioeconomic status, electronic media use of the children and sleep patterns of both parents and children. Preschoolers were divided according to whether they met the international screen time recommendations for their age. Comparisons between the two groups in various sleep measures and effects of different devices on sleep were evaluated. RESULTS: 40% of preschoolers in our cohort did not achieve the recommended sleep duration. Subjects who adhered to the screen time recommendations were from families of higher socioeconomic status, had longer sleep duration and better sleep habits. Each hour increase on portable electronic device use was associated with 11 (95%CI: -15 to -6) and 6 (95%CI: -10 to -2) minutes less of average daily sleep duration in boys and girls, respectively. Every additional hour of non-portable electronic devices use was associated with 3 min shift in social jetlag in boys. Presence of electronic devices in bedroom and their use at bedtime increased risk of social jetlag in boys with an OR of 1.40 (95%CI: 1.01 to 1.92) and 1.39 (95%CI: 1.00 to 1.95) respectively. CONCLUSION: A significant proportion of preschoolers does not obtain the recommended amount of sleep. Screen time in preschoolers affects not only sleep duration but also leads to circadian discrepancy.

How OSA Evolves From Childhood to Young Adulthood: Natural History From a 10-Year Follow-up Study.

BACKGROUND: Understanding the natural history of childhood OSA can help to determine disease prognosis and to guide risk stratification and management strategies. METHODS: To evaluate the natural history of childhood OSA and factors associated with spontaneous remission and persistent and incident OSA from childhood to late adolescence/early adulthood, a longitudinal analysis of a prospective community-based cohort was designed. Subjects from a cohort established for an OSA prevalence study were invited to participate in this 10-year follow-up study. RESULTS: Two hundred and forty-three participants (59% male) took part, and their mean age was 9.8 (SD, ± 1.8) and 20.2 (SD, ± 1.9) years at baseline and follow-up, respectively. The mean follow-up duration was 10.4 (SD, ± 1.1) years. Associations between baseline and follow-up log-transformed obstructive apnea-hypopnea index (OAHI) differed by age; a significant positive association was observed only among participants aged 10 years or older at baseline. Overall polysomnographic remission rate (with OAHI < 1 event/h at follow-up) of childhood OSA was 30%, and 69% had an OAHI < 5 events/h at follow-up. Complete remission of OSA was associated with female sex. Incidence of adolescent/adult OSA with an OAHI ≥ 5 events/h at follow-up was 22%. Male sex and higher baseline BMI z score were associated with incident OSA. CONCLUSIONS: A proportion of children with OSA, particularly female children, had complete resolution during transition to late adolescence or early adulthood. Childhood and adolescent OSA are distinct entities, with the latter more likely to persist into adulthood. Obesity and male sex are consistent key risk factors for incident OSA.

Appropriate scaling approach for evaluating peak VO2 development in Southern Chinese 8 to 16 years old.

OBJECTIVE: To investigate scaling approaches for evaluating the development of peak VO2 and improving the identification of low cardiopulmonary fitness in Southern Chinese children and adolescents. METHODS: Nine hundred and twenty Chinese children and adolescents (8 to 16 years) underwent graded cardiopulmonary exercise test on a treadmill until volitional exhaustion. Peak VO2 was corrected for the effects of body mass by ratio or allometric scaling. Z score equations for predicting peak VO2 were developed. Correlations between scaled peak VO2, z scores, body size and age were tested to examine the effectiveness of the approach. RESULTS: Eight hundred and fifty-two participants (48% male) were included in the analyses. Absolute peak VO2 significantly increased with age in both sexes (both P<0.05), while ratio-scaled peak VO2 increased only in males (P<0.05). Allometrically scaled peak VO2 increased from 11 years in both sexes, plateauing by 12 years in girls and continuing to rise until 15 years in boys. Allometically scaled peak VO2 was not correlated with body mass, but remained correlated with height and age in all but the older girls. Peak VO2 z score was not correlated with body mass, height or age. CONCLUSIONS: Absolute and allometric scaled peak VO2 values are provided for Hong Kong Chinese children and adolescents by age and sex. Peak VO2 z scores improve the evaluation of cardiopulmonary fitness, allowing comparisons across ages and sex and will likely provide a better metric for tracking change over time in children and adolescents, regardless of body size and age.

Intranasal corticosteroids for mild childhood obstructive sleep apnea--a randomized, placebo-controlled study.

BACKGROUND: The use of non-surgical treatment for childhood obstructive sleep apnea (OSA) is gaining popularity, especially in children with mild disease. OBJECTIVE: To test the hypothesis that intranasal corticosteroids reduce disease severity in children with mild OSA. STUDY DESIGN: A randomized, double-blinded, placebo-controlled trial of intranasal mometasone furoate (MF) versus placebo in children aged 6 to 18 years with mild OSA. The primary outcome was the change from baseline obstructive apnea hypopnea index (OAHI), as documented by overnight polysomnography, after four months of treatment. RESULTS: Sixty-two children were recruited but 12 dropped out. This left 24 and 26 children for final analysis in the MF and placebo group, respectively. The OAHI and oxygen desaturation index (ODI) improved significantly in the MF group only. The OAHI decreased from 2.7 ± 0.2 to 1.7 ± 0.3 in the MF group, but increased from 2.5 ± 0.2 to 2.9 ± 0.6 in the placebo group (p = 0.039). The mean changes in ODI in the MF group and placebo group were -0.6 ± 0.5 and +0.7 ± 0.4, respectively (p = 0.037). CONCLUSION: Four months of treatment with intranasal mometasone furoate effectively reduces the severity of mild OSA in children.

Endothelial function in children with OSA and the effects of adenotonsillectomy.

BACKGROUND: The association between childhood OSA and endothelial function as measured by flow-mediated dilation (FMD) and its response to OSA treatment are uncertain. The objective of this study was to compare FMD in children with OSA with nonsnoring control subjects and to examine its response to treatment. METHODS: Index cases were children aged 6 to 18 years with habitual snoring and polysomnography (PSG)-confirmed OSA (obstructive apnea hypopnea index [OAHI] > 1 events/h). Each case was paired with an age-, sex-, and BMI-matched nonsnoring control subject recruited from our previous community growth survey. All subjects underwent FMD measurement in the morning after overnight PSG. Adenotonsillectomy (AT) was offered to subjects who satisfied predefined AT operation criteria. All cases underwent repeat PSG and FMD assessment 6 months later. RESULTS: A total of 63 case-control pairs were recruited. The OSA group had a significantly higher OAHI (median, 5.3 events/h [interquartile range (IQR), 2.6-11.7] vs 0.2 events/h [IQR, 0-0.5], P < .001) and lower FMD (mean ± SD, 7.9% ± 1.3% vs 8.3% ± 0.8%; P = .04) than the control group. Thirty-two case subjects underwent AT. A significant reduction in OAHI was documented in the AT group (-8.8 events/h [IQR, -13.7 to -4.7]; P < .001) accompanied by a significant increase in FMD (+0.6% [IQR, 0.4-1.4]; P < .001), which was not observed in subjects who did not undergo AT. CONCLUSIONS: Children with OSA had reduced FMD, which was reversible with treatment.

Association Between Leisure Time Physical Activity, Cardiopulmonary Fitness, Cardiovascular Risk Factors, and Cardiovascular Workload at Work in Firefighters.

BACKGROUND: Overweight, obesity, and cardiovascular disease risk factors are prevalent among firefighters in some developed countries. It is unclear whether physical activity and cardiopulmonary fitness reduce cardiovascular disease risk and the cardiovascular workload at work in firefighters. The present study investigated the relationship between leisure-time physical activity, cardiopulmonary fitness, cardiovascular disease risk factors, and cardiovascular workload at work in firefighters in Hong Kong. METHODS: Male firefighters (n = 387) were randomly selected from serving firefighters in Hong Kong (n = 5,370) for the assessment of cardiovascular disease risk factors (obesity, hypertension, diabetes mellitus, dyslipidemia, smoking, known cardiovascular diseases). One-third (Target Group) were randomly selected for the assessment of off-duty leisure-time physical activity using the short version of the International Physical Activity Questionnaire. Maximal oxygen uptake was assessed, as well as cardiovascular workload using heart rate monitoring for each firefighter for four "normal" 24-hour working shifts and during real-situation simulated scenarios. RESULTS: Overall, 33.9% of the firefighters had at least two cardiovascular disease risk factors. In the Target Group, firefighters who had higher leisure-time physical activity had a lower resting heart rate and a lower average working heart rate, and spent a smaller proportion of time working at a moderate-intensity cardiovascular workload. Firefighters who had moderate aerobic fitness and high leisure-time physical activity had a lower peak working heart rate during the mountain rescue scenario compared with firefighters who had low leisure-time physical activities. CONCLUSION: Leisure-time physical activity conferred significant benefits during job tasks of moderate cardiovascular workload in firefighters in Hong Kong.

Management based on exhaled nitric oxide levels adjusted for atopy reduces asthma exacerbations in children: A dual centre randomized controlled trial.

While several randomized control trials (RCTs) have evaluated the use of fractional exhaled nitric oxide (FeNO) to improve asthma outcomes, none used FeNO cut-offs adjusted for atopy, a determinant of FeNO levels. In a dual center RCT, we assessed whether a treatment strategy based on FeNO levels, adjusted for atopy, reduces asthma exacerbations compared with the symptoms-based management (controls). Children with asthma from hospital clinics of two hospitals were randomly allocated to receive an a-priori determined treatment hierarchy based on symptoms or FeNO levels. There was a 2-week run-in period and they were then reviewed 10 times over 12-months. The primary outcome was the number of children with exacerbations over 12-months. Sixty-three children were randomized (FeNO = 31, controls = 32); 55 (86%) completed the study. Although we did achieve our planned sample size, significantly fewer children in the FeNO group (6 of 27) had an asthma exacerbation compared to controls (15 of 28), P = 0.021; number to treat for benefit = 4 (95% CI 3-24). There was no difference between groups for any secondary outcomes (quality of life, symptoms, FEV1 ). The final daily inhaled corticosteroids (ICS) dose was significantly (P = 0.037) higher in the FeNO group (median 400 µg, IQR 250-600) compared to the controls (200, IQR100-400). Taking atopy into account when using FeNO to tailor asthma medications is likely beneficial in reducing the number of children with severe exacerbations at the expense of increased ICS use. However, the strategy is unlikely beneficial for improving asthma control. A larger study is required to confirm or refute our findings.

A 4-year prospective follow-up study of childhood OSA and its association with BP.

BACKGROUND: Childhood OSA is a prevalent condition associated with raised BP as documented in cross-sectional studies. This study aimed to determine whether baseline or change in OSA severity was associated with ambulatory BP at 4-year follow-up. METHODS: Children who participated in our previous OSA prevalence research were invited to undergo a repeat overnight sleep study and 24-h ambulatory BP monitoring in this 4-year follow-up study. BP parameters of subjects with differing baseline OSA severity, that is, obstructive apnea-hypopnea index (OAHI) < 1/h, 1 to 5/h, and > 5/h, were compared. Overweight and normal-weight children were analyzed separately. RESULTS: One hundred eighty-five of 306 subjects (60%) were included in the analysis, of whom 58 were overweight at baseline. Linear increasing trends of wake systolic BP (SBP), wake diastolic BP (DBP), and sleep SBP z scores at follow-up were found across groups of increasing baseline OSA severity in the normal weight but not in the overweight subgroup. After adjusting for BMI z score, baseline OAHI was independently associated with all BP z scores at follow-up but not associated with changes in BP z scores across 4 years. On the other hand, change in OAHI was independently associated with sleep SBP and DBP z scores at follow-up and with changes in sleep SBP and DBP z scores across 4 years. CONCLUSIONS: This study provides longitudinal data as additional proof that childhood OSA is associated with elevated BP independent of obesity.

Orlistat improves endothelial function in obese adolescents: a randomised trial.

AIM: To investigate the effect of orlistat on endothelial function in obese adolescents. METHODS: Single-blind 10-week controlled trial of 67 normolipidaemic obese adolescents randomised into three groups. Group 1 (diet alone), Group 2 (diet and orlistat), Group 3 (diet, orlistat and exercise). Endothelial function measured by flow-mediated dilatation (FMD) of the brachial artery, anthropometric parameters, blood pressure, fasting blood lipids, insulin and glucose levels were recorded at baseline and at 10 weeks. RESULTS: Sixty four subjects completed the study. Groups were comparable at baseline. FMD increased significantly with orlistat (Groups 2 and 3) but not in Group 1. Orlistat treatment resulted in significantly reduced bodyweight, body mass index (BMI), waist circumference, total and low-density lipoprotein (LDL) cholesterol levels. High-density lipoprotein cholesterol levels were unchanged. Triglyceride and insulin levels were significantly reduced in all three groups. The reduction in cholesterols did not correlate with reductions in weight and BMI. A slight reduction of body fat, both with and without orlistat treatment, correlated with reduction in BMI after adjustment for baseline values. Blood pressure was unaltered by orlistat. Calorie intake was reduced with orlistat, and the decrease noted in % fat and increase in % carbohydrate was significant only in those taking orlistat. The addition of exercise (Group 3 compared with Group 2) altered no parameter. CONCLUSIONS: Orlistat improves endothelial function and reduces bodyweight, BMI, fasting total and LDL-cholesterol in obese adolescents when combined with dietary control. Improvement in endothelial function if maintained could reflect long-term cardiovascular benefit.

Prevalence of habitual snoring and its correlates in young children across the Asia Pacific.

AIMS: To evaluate: (i) the prevalence of habitual snoring (HS) in a large sample of children aged from birth to 36 months in 14 countries across Asia Pacific; and (ii) the different correlates associated with HS in Caucasians, Chinese and non-Chinese, non-Caucasian Asians. METHODS: This was a multi-centre, cross-sectional survey conducted across Asia Pacific. Parents/caregivers of 23,481 infants and toddlers completed an expanded version of the Brief Infant Sleep Questionnaire. We defined HS as snoring more than three nights per week. RESULTS: Chinese and non-Caucasian non-Chinese (NCNC) children had a lower prevalence of HS across the age range from birth to 3 years than their Caucasian counterparts (6.2% and 5.1% vs. 11%, P < 0.01). Boys had a higher prevalence of HS compared to girls (χ(2) = 98.5, P < 0.0001). History of prematurity (OR = 1.37-1.56, CI (1.1-2.17), P < 0.01) and gender (OR = 1.53-1.54, CI (1.26-1.85), P < 0.0001) were found to be significant predictors for HS. Current breastfeeding (OR = 0.69, CI (0.54-0.88), P < 0.005) and greater parental age (OR = 0.86, CI (0.78-0.96), P < 0.01) were protective against HS among NCNC children. HS was less prevalent in younger Chinese subjects (OR = 0.88, CI (0.84-0.93), P < 0.0001). In Caucasians, parents' education (OR = 0.78, CI (0.67-0.91), P < 0.005) and their not sleeping in the same room as their child (OR = 0.62, CI (0.45-0.86), P < 0.005) were negatively associated with parental report of HS. CONCLUSIONS: Prevalence of HS shows racial differences among countries across Asia Pacific. Future studies should assess craniofacial structure and body fat distribution as contributory factors for this differential prevalence.

Reduced flow-mediated vasodilation of brachial artery in children with primary snoring.

BACKGROUND: Sleep disordered breathing, especially obstructive sleep apnea, is associated with endothelial dysfunction in both adults and children. However, the role of primary snoring (PS) on endothelial function has not been investigated. This study aimed to examine flow-mediated vasodilation (FMD) in both normal weight and overweight children with PS. METHODS: Children aged 6-18 years with habitual snoring were recruited from our sleep disorder clinic. Non-snoring controls were recruited from participants of a community growth survey. All subjects underwent polysomnography and FMD evaluation on the same day. Children with body mass index of greater than the 85th percentile of the local reference were defined as overweight. Subjects were divided into groups of normal weight, overweight, non-snorers and PS for comparisons. RESULTS: Two hundred and one children, of whom 83 were overweight, with a mean ± SD age of 11.3 ± 2.7 years were recruited. Seventy three out of 201 children had PS. Both normal weight (7.9 ± 1.3 vs. 8.5 ± 0.9, p=0.012) and overweight subjects (7.4 ± 1.4 vs. 8.1 ± 1.1, p=0.006) with PS had significantly reduced FMD than the non-snoring controls. Multivariate linear regression model showed that PS was independently associated with reduced FMD in both normal weight (p=0.014) and overweight subgroups (p=0.016) after controlling for obstructive apnea hypopnea index. CONCLUSIONS: PS in children is associated with reduced FMD, independent of obesity.

Natural history of primary snoring in school-aged children: a 4-year follow-up study.

BACKGROUND: The objective of this study was to examine the natural history of childhood primary snoring (PS) and to identify predictive clinical symptoms and risk factors associated with PS progression to obstructive sleep apnea (OSA). METHODS: Children aged 6 to 13 years old who received a diagnosis of PS in our previous community-based OSA prevalence study were invited to undergo repeat polysomnography (PSG) at 4-year follow-up. Subjects with an obstructive apnea hypopnea index (OAHI) ≥ 1 were classified as having OSA at follow-up. RESULTS: Seventy children (60% boys) with a mean age of 14.7 ± 1.8 years were analyzed in this follow-up study. The mean duration of follow-up was 4.6 ± 0.6 years. At follow-up, 26 subjects (37.1%) progressed to OSA, of whom five (7.1%) had moderate to severe disease (OAHI ≥ 5). Twenty-two (31.4%) remained at PS, and 18 (25.7%) had complete resolution of their snoring with normal PSG. Persistent snoring had a positive predictive value of 47.7% and a negative predictive value of 86.4% for progression from PS to OSA. Multivariate logistic regression analysis showed that persistent overweight/obesity was a significant risk factor for the development of OSA at follow-up, with an OR of 7.95 (95% CI, 1.43-44.09). CONCLUSIONS: More than one-third of school-aged children with PS progressed to OSA over a 4-year period, although only 7.1% developed moderate to severe disease. Weight control may be an important component in the management of PS because obesity was found to be a significant risk factor for PS progression.

Follow up of aerobic capacity in children affected by severe acute respiratory syndrome.

BACKGROUND AND OBJECTIVE: The aim of this study was to investigate the aerobic capacity of children 3 years after they were diagnosed with severe acute respiratory syndrome (SARS). METHODS: Twenty-seven patients who completed both pulmonary function and maximal aerobic capacity tests at 6 and 15 months after the acute illness were invited to return for reassessment. RESULTS: Twenty-one patients (median age 18.2 years, interquartile range (IQR) 16.5-19.7) completed all investigations at 36 months. Pulmonary function was normal in all patients. Maximal aerobic capacity, peak oxygen pulse (peak VO(2) ) and ventilatory anaerobic threshold showed significant improvements compared with values measured at 6 months in both boys and girls. In girls, ventilatory efficiency (ventilatory equivalents for oxygen and carbon dioxide) and perfusion of the lungs (end-tidal partial carbon dioxide pressure) had not increased further compared with the values measured at 15 months. Although peak VO(2) improved further at 36 months in patients with or without persistent radiological abnormalities, the values were 68% (IQR 50-84) and 74% (IQR 60-99), respectively, of those for normal control subjects. CONCLUSIONS: There were improvements in aerobic capacity at 36 months in children affected by SARS; however, the measured values remained suboptimal.

Night sweats in children: prevalence and associated factors.

OBJECTIVE: The authors aimed to examine the prevalence and factors associated with night sweats (NS) in primary school children. STUDY DESIGN: Cross-sectional design. RESULTS: Among 6381 children (median age 9.2 (7.7-10.7) years) with complete information on NS, 3225 were boys (50.5%). 747 children (11.7%) were reported to have weekly NS in the past 12 months. Boys were more likely than girls to have NS (p<0.0001). Children with NS were more likely to have sleep-related symptoms and respiratory and atopic diseases. In addition, they were more likely to be hyperactive and have frequent temper outbursts. Using an ordinal regression model, NS was found to be significantly associated with male gender, younger age, allergic rhinitis, tonsillitis and symptoms suggestive of obstructive sleep apnoea, insomnia and parasomnia. CONCLUSION: NS is prevalent among school-aged children and is associated with the presence of sleep-related symptoms and respiratory and atopic diseases.