Hung K. So

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.

Induced sputum inflammatory measures correlate with disease severity in children with obstructive sleep apnoea

Objective: To establish the association between airway inflammation and severity of obstructive sleep apnoea (OSA) in children. Methods: Consecutive children presenting with symptoms suggestive of OSA were recruited. They completed a sleep apnoea symptom questionnaire, underwent physical examination, spirometry, sputum induction and an overnight polysomnography. Adequate sputum contained <50% squamous epithelial cells, and OSA was diagnosed if the obstructive apnoea index was >1. Results: 73 children with a median (interquartile range (IQR)) age of 11.3 (10.0–13.2) years were recruited. There were 21 girls and the median body mass index of the group was 24.0 (18.0–27.0) kg/m2. The most common presenting symptoms were habitual snoring, mouth breathing and prone sleeping position. Sputum induction was successful in 43 (59%) children, of whom 14 were found to have OSA. Children with OSA had significantly greater percentage sputum neutrophil than those without OSA (18.5 (IQR 8.0–42.0) v 4 (IQR 3.0–11.3), p = 0.006). On multiple regression analysis, percentage sputum neutrophil was significantly associated with OSA (odds ratio  = 1.1, p = 0.013). Conclusion: Children with OSA had airway inflammation characterised by a marked increase in neutrophils. Further studies are needed to confirm these findings and to better define the downstream cellular interactions and molecular pathogenesis in childhood OSA.

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.

Socioenvironmental Factors Associated With Constipation in Hong Kong Children and Rome III Criteria

Objective: Data regarding the prevalence of constipation in the general population of Asian children using internationally standardized definitions are scarce. Environmental factors surrounding a childs day to day living may trigger or perpetuate constipation and encourage postponement of defecation. Methods: A territory-wide cross-sectional questionnaire survey was conducted in 2318 Hong Kong Chinese elementary school students. Constipation was defined by pediatric Rome III criteria. Results: The mean age of the children was 9 ± 1.9 years; 51% were boys. Two hundred eighty-two children (12.2%, 95% confidence interval [CI] 10.9%–13.5%) were found to have constipation. Children ages 6 to 7 years had the highest prevalence (16.8%, 95% CI 13.8%–19.8%). There was no difference in prevalence between boys and girls (11.6% vs 12.3%; P > 0.05) and between obese and nonobese children (11.5% vs 11.1%; P > 0.05). In univariate analysis, constipation was found to be significantly more prevalent among those children who lived with neither parent, had inadequate company of parents at home, refused to pass bowel movements in school, spent long hours doing homework, had inadequate sleep, and had decreased fiber intake and frequent consumption of fast food (P < 0.05). Multivariate analysis identified refusal to pass bowel movements in school toilets (odds ratio [OR] 1.97, 95% CI 1.42%–2.74%), having dinner with one/both parents <50% of time (OR 1.52, 95% CI 1.01%–2.31%), nighttime sleep <7 hours (OR 1.87, 95% CI 1.04%–3.33%), and frequent consumption of fast food (OR 1.14, 95% CI 1.03%–1.26%) to be independent factors associated with constipation. Conclusions: Socioenvironmental factors are associated with childhood constipation, and bringing them to the awareness of the public may help prevent or stop the progression of childhood constipation at its early stages.

Neurocognitive dysfunction and grey matter density deficit in children with obstructive sleep apnoea

BACKGROUND Cerebral structural changes related to obstructive sleep apnoea (OSA) have been reported in adult OSA patients; however, similar data and their associations with neurocognitive dysfunction are scarce in childhood OSA. OBJECTIVE To compare neurocognitive function, regional grey matter density and cerebral volume in children with and without OSA. METHODS Fifty OSA cases and 27 normal controls underwent a panel of neurocognitive tests. High resolution 3-dimensional magnetic resonance images of the brain were obtained from 23 OSA cases and 15 gender and age matched controls. Total cerebral volume and regional grey matter density were analyzed using voxel-based morphometry technique and compared between the two groups. Individuals with an obstructive apnoea hypopnoea index (OAHI) > 5 were defined as having moderate-to-severe OSA. RESULTS Children with OSA showed significantly reduced attention and visual-fine motor coordination scores compared with controls. Grey matter volume deficit was observed in prefrontal and temporal regions of cases with moderate-to-severe OSA only. Significant negative correlations were found between the visual-fine motor coordination score and the ratio of grey matter volume over total brain volume. CONCLUSION Children with OSA had impaired attention and visual-fine motor coordination. Regional grey matter reduction was evident in children with more severe OSA.

Cough frequency in children with mild asthma correlates with sputum neutrophil count

Background: A study was undertaken to measure cough frequency in children with stable asthma using a validated monitoring device, and to assess the correlation between cough frequency and the degree and type of airway inflammation. Methods: Thirty six children of median age 11.5 years (interquartile range (IQR) 9–14) with stable asthma were recruited. They underwent spirometric testing, exhaled nitric oxide (eNO) measurement, sputum induction for differential cell count, and ambulatory cough monitoring for 24 hours. Coughing episodes were counted both as individual spikes and as clusters. Results: All children had mild intermittent asthma and their median forced expiratory volume in 1 second and eNO were 83.3% (IQR 81.1–97.6) and 56.1 ppb (IQR 37.4–105), respectively. The median number of cough episodes per day was 25.5 (IQR 16–42.8). Sputum induction was successful in 69% of the subjects and cough frequency was found to have a significant positive correlation with sputum neutrophil count (r = 0.833, p = 0.0001). Conclusions: Children with stable mild asthma have increased cough frequency that might be driven by a neutrophilic inflammatory pathway.

Adipokines in Children With Obstructive Sleep Apnea and the Effects of Treatment

BACKGROUND The objective of this study was to evaluate circulating adipokines concentration in children with and without obstructive sleep apnea (OSA) and to determine the effects of treatment of OSA on their plasma concentration. METHODS Children with habitual snoring and symptoms suggestive of OSA were consecutively recruited. Their parents completed a sleep apnea symptom questionnaire, and the subjects underwent physical examination and an overnight polysomnography (PSG). OSA was diagnosed if they had an obstructive apnea index > 1. Fasting serum adiponectin, leptin, and lipid profiles were taken after overnight PSG. The subjects were divided into groups as obese, nonobese, and with and without OSA for comparison. RESULTS One hundred forty-one children, of whom 96 were boys, with a median (interquartile range) age of 10.8 (8.5-12.8) years were recruited. Forty-three subjects had OSA. Subjects with OSA did not have significantly different adiponectin and leptin concentrations than those without OSA for both the obese and nonobese groups. Stepwise multiple linear regressions revealed that systolic BP, age, high-density lipoprotein cholesterol, and BMI z-score were independently associated with adiponectin, whereas diastolic BP, triglyceride, height, and BMI z-score were independently associated with leptin concentration. Sixteen children with OSA underwent treatment, and there was reduction in their plasma adiponectin concentration after intervention, but such change became insignificant after controlling for change in the BMI z-score. CONCLUSIONS BMI rather than OSA was the main determinant of adipokines in children.

Leukotriene receptor antagonist in the treatment of childhood allergic rhinitis—a randomized placebo‐controlled study

This study was designed to assess the hypothesis that leukotriene receptor antagonists (LTRAs) would provide additional symptom relief in asthmatic children with persistent AR already taking regular antihistamine. The effects of 16‐week treatment of LTRA in addition to fexofenadine (FEX) on persistent AR in asthmatic children were examined.

Interrupter Respiratory Resistance in Healthy Chinese Preschool Children

BACKGROUND Interrupter respiratory resistance (Rint) is useful in evaluating lung function in children who cannot perform the traditional lung function tests. However, available reference Rint values are confined to whites. Our aims were as follows: (1) to establish reference values in local preschool Chinese children, (2) to examine their relationship with demographic and anthropometric factors, and (3) to determine the 10-min and 6-week repeatability of Rint. METHODS Rint was measured in preschool children from randomly chosen local kindergartens, and the repeatability of Rint measurement was assessed in a subgroup of subjects 10 min and 6 weeks after the initial measurement. RESULTS Rint measurement was performed in 509 children between 4 and 6 years of age. Age, height, and weight significantly inversely correlated with Rint values. However, on multiple linear regression, height was the only variable that independently correlated with Rint. Repeat measurements obtained 10 min and 6 weeks after the initial reading in 45 children showed good agreement with little variability, and the interclass correlation coefficients for 10-min and 6-week measurements were 0.877 and 0.923, respectively. CONCLUSION Rint reference centile curves for Chinese preschool children have been determined. Rint in preschool Chinese children has good short- and long-term repeatability.