The role of nocturnal pulse oximetry in the screening for obstructive sleep apnea in obese children and adolescents.

BACKGROUND AND AIM: Obesity is a known risk factor for the development of obstructive sleep apnea (OSA) in children. Early screening is essential because of the possible complications associated with OSA. At present, the gold standard for diagnosing OSA is polysomnography, which however has multiple limitations. The aim of this study is to examine the role of nocturnal oximetry as a screening tool for OSA in obese children and adolescents. MATERIALS AND METHODS: This retrospective study included obese children who underwent a polysomnography at the Antwerp University Hospital between November 2010 and May 2014. Their oximetries were scored manually, blinded for the polysomnography results, according to Brouilette et al. OSA was defined as an obstructive apnea-hypopnea index (oAHI) ≥ 2 on polysomnography. RESULTS: This study included 130 obese patients (38% boys, mean age 12 years). Polysomnography results determined 44 patients (34%) with a diagnosis of OSA. Oximetry results classified 16 patients as positive, 43 as negative, and 71 as inconclusive. Further analysis of the positive and negative oximetry results showed a sensitivity and specificity of 58% and 88%, respectively, with a negative and positive predictive value of 81% and 69%, respectively. A second analysis, using the oxygen desaturation index, showed inferior results in comparison to the score attained by Brouillette (sensitivity 57%, specificity 73%). CONCLUSIONS: These results suggest that oximetry alone is insufficient as a screening tool for OSA in obese children. Other screening methods need to be explored in the future.

Association study and mutation analysis of adiponectin shows association of variants in APM1 with complex obesity in women.

We performed an association study and mutation analysis of the adiponectin (APM1) gene to study its involvement in the development of obesity. We also studied the interaction with peroxisome proliferator-activated receptor gamma (PPARgamma). 223 obese women and 87 healthy female control subjects were used for association analysis. Mutation analysis was done on 95 morbidly obese adults and 123 overweight and obese children and adolescents. We selected 6 haplotype tagging SNPs in APM1 and the Pro12Ala variant (rs1805192) in PPARgamma to study the interaction. The G allele of rs2241766 was more common in controls (cases 10.8% vs. controls 18.4%, nominal p = 0.011; OR = 0.57, nominal p = 0.018). The rs2241766/rs3774261 haplotype was also associated with obesity (nominal p = 0.004). Only the latter association remained significant after controlling for the False Discovery Rate. Resequencing of exon 2, exon 3 and intron 2 in 95 individuals did not reveal any SNPs in high linkage disequilibrium with rs2241766. No interaction with the Pro12Ala variant in PPARgamma was detected. Mutation analysis of APM1 did not identify mutations. In conclusion, we found an association of an APM1 haplotype with obesity and found that APM1 mutations are not a common cause of monogenic obesity in our cohort.

Sleep-disordered breathing: a new risk factor of suspected fatty liver disease in overweight children and adolescents?

INTRODUCTION: The aim of this retrospective study was to investigate if sleep-disordered breathing (SDB) was an independent predictor of suspected fatty liver disease in a clinical sample of overweight children and adolescents. MATERIALS AND METHODS: Consecutive overweight and obese children attending a pediatric obesity clinic underwent polysomnography, fasting blood sample, and abdominal ultrasound. RESULTS AND DISCUSSION: The respiratory disturbance index, percentage of total sleep time with SO2 < 90%, and SaO2nadir were associated with higher alanine amino-transferases (ALT) independent of abdominal obesity. Multiple logistic regression selected waist circumference (odds ratio = 1.05; p = 0.05) and SaO2nadir (odds ratio = 0.87; p = 0.03) as predictors of suggestive fatty liver disease, defined as ALT > 40 U/L and/or hyperechoic liver on abdominal ultrasound. This study supports the association between the severity of SDB and suspected fatty liver disease in a clinical sample of overweight children and adolescents. We recommend more research on the influence of SDB on the development of fatty liver disease and on the effect of treating sleep apnea on liver function parameters.

Sleep-disordered breathing, obesity, and airway inflammation in children and adolescents.

BACKGROUND: To investigate the relationship between obstructive sleep apnea syndrome (OSAS) and exhaled nitric oxide (eNO) in overweight children and adolescents without asthma or atopy and to assess whether obesity per se is associated with increased airway inflammation. METHODS: Consecutive overweight subjects without symptoms of asthma or allergy were recruited at a pediatric obesity clinic. A normal-weight control group without OSAS and asthma or allergy was also recruited. All subjects underwent polysomnography and two measurements of eNO (afternoon and morning after polysomnography). RESULTS: Controlling for age, the mean (+/- SD) afternoon eNO concentration was significantly higher in the snoring group (14.1 +/- 1.1 parts per billion [ppb]) compared with the normal-weight group (10.1 +/- 0.8 ppb; p = 0.03) and with the overweight group with normal polysomnography findings (8.9 +/- 0.8 ppb; p = 0.007). The afternoon eNO concentration was also different between the OSAS group (11.9 +/- 1.0 ppb) and the overweight group with normal polysomnography findings (p = 0.03). Morning eNO values were higher in the OSAS group (12.3 +/- 1.1 ppb) than in the normal weight group (9.9 +/- 0.8 ppb; p = 0.047) and in the overweight control group (9.7 +/- 0.7 ppb; p = 0.02). BMI z score was not significantly correlated with afternoon eNO concentration or with morning eNO concentration. CONCLUSION: This study illustrates that both habitual snoring and OSAS are associated with increased airway inflammation in overweight children as assessed by higher eNO levels. Furthermore, it was demonstrated that childhood obesity in the absence of sleep-disordered breathing is not associated with increased airway inflammation.

Sleep-disordered breathing and uric acid in overweight and obese children and adolescents.

OBJECTIVE: The aim of this study was to determine whether the severity of sleep-disordered breathing (SDB) was associated with increased levels of uric acid (UA), both in serum and in urine, as a marker of tissue hypoxia, in a sample of overweight and obese subjects, irrespective of indexes of adiposity. METHODS: Consecutive subjects underwent polysomnography, fasting blood sampling, and 24-h urine collection. Outcome parameters were serum UA, UA excretion ([24-h urinary UA x serum creatinine]/urine creatinine) and urinary UA/creatinine ratio. RESULTS: A total of 93 subjects were included (44% boys; mean [+/- SD] age = 11.1 +/- 2.5; 73% obese). A fasting measurement of serum UA levels was available for 62 patients. The respiratory disturbance index was a significant covariate (beta = 0.09 +/- 0.03; p = 0.01) in the regression model for serum UA, controlling for sex (beta = 0.32 +/- 0.29; p = 0.3), puberty (beta = 0.87 +/- 0.34; p = 0.01), and waist circumference (beta = 0.04 +/- 0.01; p = 0.005). The percentage of total sleep time with arterial oxygen saturation < or = 89% (beta = 0.94 +/- 0.45; p = 0.04) was also significantly associated with serum UA level, controlling for sex (beta = 0.22 +/- 0.30; p = 0.5), puberty (beta = 0.83 +/- 0.35; p = 0.02), and waist circumference (beta = 0.04 +/- 0.02; p = 0.02). None of the SDB variables correlated with UA excretion or with urinary UA/creatinine ratio. CONCLUSION: This study in overweight children and adolescents demonstrated a relationship between the severity of sleep apnea and increased levels of serum UA, independent of abdominal adiposity. In view of the known associations between UA and cardiovascular risk, this finding may contribute to the mechanisms linking SDB with cardiovascular morbidity.

Sleep-disordered breathing in overweight and obese children and adolescents: prevalence, characteristics and the role of fat distribution.

AIMS: To determine the prevalence of sleep-disordered breathing (SDB) in a clinical sample of overweight and obese children and adolescents, and to examine the contribution of fat distribution. METHODS: Consecutive subjects without chronic lung disease, neuromuscular disease, laryngomalacia, or any genetic or craniofacial syndrome were recruited. All underwent measurements of neck and waist circumference, waist-to-hip ratio, % fat mass and polysomnography. Obstructive apnoea index > or =1 or obstructive apnoea-hypopnoea index (OAHI) > or =2, further classified as mild (2< or =OAHI<5) or moderate-to-severe (OAHI> or =5), were used as diagnostic criteria for obstructive sleep apnoea (OSA). Central sleep apnoea was diagnosed when central apnoeas/hypopnoeas > or =10 s were present accompanied by >1 age-specific bradytachycardia and/or >1 desaturation <89%. Subjects with desaturation < or =85% after central events of any duration were also diagnosed with central sleep apnoea. Primary snoring was diagnosed when: snoring was detected by microphone and normal obstructive indices and saturation. RESULTS: 27 overweight and 64 obese subjects were included (40 boys; mean (standard deviation (SD)) age 11.2 (2.6) years). Among the obese children, 53% were normal, 11% had primary snoring, 11% had mild OSA, 8% had moderate-to-severe OSA and 17% had central sleep apnoea. Half of the patients with central sleep apnoea had desaturation <85%. Only enlarged tonsils were predictive of moderate-to-severe OSA. On the other hand, higher levels of abdominal obesity and fat mass were associated with central sleep apnoea. CONCLUSION: SDB is very common in this clinical sample of overweight children. OSA is not associated with abdominal obesity. On the contrary, higher levels of abdominal obesity and fat mass are associated with central sleep apnoea.