Chun T. Au

Ambulatory blood pressure in children with obstructive sleep apnoea: a community based study

Background: Childhood obstructive sleep apnoea (OSA) is increasingly being recognised. Its effects on blood pressure (BP) elevation and hypertension are still controversial. Objective: To evaluate the association between OSA and ambulatory BP in children. Methods: Children aged 6–13 years from randomly selected schools were invited to undergo overnight sleep study and ambulatory BP monitoring after completing a validated OSA questionnaire. OSA was diagnosed if the obstructive apnoea–hypopnoea index (AHI) was >1, and normal controls had AHI <1 and snoring <3 nights per week. Children with OSA were subdivided into a mild group (AHI 1–5) and moderate to severe group (AHI >5). Results: 306 subjects had valid sleep and daytime BP data. Children with OSA had significantly higher BP than normal healthy children during both sleep and wakefulness. BP levels increased with the severity of OSA, and children with moderate to severe disease (AHI >5) were at significantly higher risk for nocturnal systolic (OR 3.9 (95% CI 1.4 to 10.5)) and diastolic (OR 3.3 (95% CI 1.4 to 8.1)) hypertension. Multiple linear regression revealed a significant association between oxygen desaturation index and AHI with daytime and nocturnal BP, respectively, independent of obesity. Conclusions: OSA was associated with elevated daytime and nocturnal BP, and is an independent predictor of nocturnal hypertension. This has important clinical implications as childhood elevated BP predicts future cardiovascular risks. Future studies should examine the effect of therapy for OSA on changes in BP.

Blood Pressure is Elevated in Children with Primary Snoring

OBJECTIVES To compare ambulatory blood pressure (ABP) in nonoverweight, prepubertal children with and without primary snoring (PS), and to investigate whether PS is a part of the dose-response relationship between sleep-disordered breathing (SDB) and BP in children. STUDY DESIGN This was a cross-sectional community-based study involving 190 children age 6 to 13 years. Each participant underwent an overnight sleep study and ABP monitoring after completing a validated sleep symptoms questionnaire. Individual systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial BP were calculated for wake and sleep periods. Subjects were hypertensive if mean SBP or DBP was > 95th percentile (relative to sex and height) of reference. RESULTS A total of 56 nonsnoring controls, 46 children with PS, 62 children with an apnea-hypopnea index (AHI) of 1 to 3, and 26 children with an AHI > 3 were identified. The daytime and nighttime BP increased across the severity spectrum of SDB. The dose-response trends for the proportion of subjects with nighttime systolic and diastolic hypertension also were significant. Nighttime DBP was significantly higher in the children with PS compared with controls after adjusting for age, sex, and body mass index. CONCLUSIONS PS was demonstrated to be an aspect of the dose-response relationship between SDB and BP in children and should not be considered completely benign.

Epidemiology of obstructive sleep apnoea syndrome in Chinese children: a two-phase community study

Objective To determine the prevalence and risk factors of obstructive sleep apnoea syndrome (OSAS) in Chinese children using a two-phase community-based study design. Methods Children from 13 primary schools were randomly recruited. A validated OSAS screening questionnaire was completed by their parents. Children at high risk of OSAS and a randomly chosen low-risk group were invited to undergo overnight polysomnographic study and clinical examination. The the sex-specific prevalence rate was measured using different cutoffs (obstructive apnoea hypopnoea index ≥1, ≥1.5, ≥3 and ≥5 and obstructive apnoea index ≥5) and risk factors associated with OSAS were evaluated with logistic regression. Results 6447 completed questionnaires were returned (out of 9172 questionnaires; 70.3%). 586 children (9.1%; 405 boys and 181 girls) children belonged to the high-risk group. A total of 619 (410 and 209 from the high and low-risk group, respectively) subjects underwent overnight polysomnagraphy. Depending on the cutoffs, the prevalence rate of childhood OSAS varied from 4.8% to 40.3%. Using the International Criteria of Sleep Disorders version II, the OSAS prevalence for boys and girls was 5.8% and 3.8%, respectively. Male gender, body mass index z-score and increased adenoid and tonsil size were independently associated with OSAS. Conclusions The prevalence rate of OSAS in children was contingent on the cutoff used. The inclusion of symptoms as a part of the diagnostic criteria greatly reduced the prevalence. A further prospective and outcome study is needed to define a clinically significant diagnostic cutoff for childhood OSAS.

Prevalence and risk factors of habitual snoring in primary school children.

OBJECTIVE Our study aimed to determine the prevalence of habitual snoring (HS) in primary school children and to evaluate the diurnal symptoms and conditions that may be associated with it. METHODS A validated questionnaire completed by parents was used to assess the sleep and daytime behaviors of Chinese children aged 5 to 14 years. Thirteen primary schools in two representative districts were randomly selected. RESULTS A total of 6,349 out of 9,172 questionnaires (response rate 69.2%) with complete answers were returned. The prevalence rate of HS was 7.2%. Male sex (odds ratio [OR] [95% CI]: 2.5 [1.7-3.6]), BMI z score (OR [95% CI]: 1.4 [1.1-1.6]), maternal HS (OR [95% CI]: 3.4 [2.0-5.7]), paternal HS (OR [95% CI]: 3.8 [2.7-5.5]), allergic rhinitis (OR [95% CI]: 2.9 [2.0-4.2]), asthma (OR [95% CI]: 2.4 [1.2-5.2]), nasosinusitis (OR [95% CI]: 4.0 [1.5-10.6]), and tonsillitis (OR [95% CI]: 3.1 [1.9-5.1]) in the past 12 months were identified to be independent risk factors associated with HS. HS was also associated with daytime, nocturnal, parasomniac, and sleep-related breathing symptoms. HS was demonstrated to be an independent risk factor for parent-reported poor temper (OR [95% CI]: 1.9 [1.4-2.5]), hyperactivity (OR [95%CI]: 1.7 [1.2-2.5]), and poor school performance (OR [95% CI]: 1.7 [1.2-2.5]). CONCLUSIONS HS was a significant and prevalent problem in primary school children. Male sex, obesity, parental HS, atopic symptoms, and history of upper respiratory infections were significant risk factors. HS was also associated with sleep-disordered breathing symptoms and adverse neurobehavioral outcomes.

Nocturnal Enuresis in Children: Prevalence, Correlates, and Relationship with Obstructive Sleep Apnea

OBJECTIVES To examine the prevalence and correlates of nocturnal enuresis (NE) in primary school children, and to compare the prevalence of NE in children with and those without obstructive sleep apnea (OSA). STUDY DESIGN Parents of children aged 6-11 years completed a questionnaire eliciting information on sleep-related symptoms, demography, and family and past medical history. Children screened due to high risk for OSA, along with a randomly chosen low-risk group, underwent overnight polysomnography (PSG). RESULTS A total of 6147 children (3032 girls) were studied. The overall prevalence of NE (≥1 wet night/month) was 4.6% (6.7% of boys and 2.5% of girls). Boys had a significantly greater prevalence across all age groups. In 597 children (215 girls) who underwent PSG, the prevalence of NE was not greater in children with OSA, but was increased with increasing severity of OSA in girls only. Boys with NE had longer deep sleep duration. Sex and sleep-related symptoms were associated with NE. CONCLUSIONS This community-based study demonstrated a sex-associated prevalence of NE in relation to increasing OSA severity.

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.

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. Pediatr Pulmonol. 2015; 50:535–543.

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.

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.

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.