The biology and genetics of obesity and obstructive sleep apnea

Anthropometric and Dental Measurements in Children with Obstructive Sleep Apnea

STUDY OBJECTIVES

A number of authors have shown that children with OSA are more likely to have certain physical characteristics than healthy controls. With this in mind, our objectives were to collect normative baseline data and determine if there was a significant difference in anthropometric and dental measurements between children with OSA and age-matched nonsnoring controls.

METHODS

Children 2 to 12 y of age, in whom OSA was diagnosed by overnight polysomnography, were recruited to our experimental group. Age-matched nonsnoring controls were screened for signs of sleep-disordered breathing. Anthropometric measurements, including waist, neck, and hip circumferences, and waist-hip and neck-waist ratios, were obtained on all study participants preoperatively. Dental casts were acquired to determine intertooth distances and palatal height.

RESULTS

Sixty-one children (42 with OSA [69%] and 19 controls [31%]) with a mean age of 4.7 y participated in the study. Waist and hip circumferences were significantly larger in children with OSA (p = 0.001 and 0.001, respectively). However, there was no difference in neck circumference and waist-hip ratios between the two groups. Neck-waist ratio in children with OSA was significantly smaller than in controls (p = 0.001). Intertooth distance for the first (p < 0.0001) and second deciduous (p = 0.0002) and first permanent molars (p = 0.022) were significantly narrowed in children with OSA; however, no difference was seen in palatal height between groups. Body mass index was similar between groups (p = 0.76).

CONCLUSIONS

Anthropometric and dental measurements were significantly different in children with OSA compared to nonsnorers. Future studies with a large sample size may allow us to determine if these measurements can be used by clinicians to identify children at risk for OSA.

COMMENTARY

A commentary on this article appears in this issue on page 1213.

Neck circumference percentile: A screening tool for pediatric obstructive sleep apnea

RATIONALE

Large neck circumference (NC) is associated with obstructive sleep apnea (OSA) in adults, especially males. Since NC changes with age and sex, a lack of reference ranges makes neck size difficult to assess as a screening tool in children.

METHODS

Using a population-based dataset of 1,913 children, we developed reference ranges for NC by age and sex for children aged 6-17 years. In this study, we collected NC data on 245 children aged 6-17 years presenting to the Children's Hospital of Eastern Ontario for polysomnography. The association between NC>the 95th percentile and OSA (total apnea-hypopnea-index>5 events/hr and/or obstructive-apnea-index ≥ 1 event/hr) was explored. Thresholds of BMI percentile and waist circumference were also examined.

RESULTS

Individuals with NC>95th percentile for age and sex had increased risk of OSA (relative risk 1.7 [95% CI 1.0-3.0], P=0.04), compared to those with NC ≤ 95th percentile. BMI ≥ 95th percentile gave similar results (relative risk 1.8 [95% CI 1.1-2.9], P=0.02). When examined by sex, the association was significant in males ≥ 12 years (relative risk 3.3 [95% CI 1.0-10.4], P=0.04), but not females (P=0.63). Neither BMI  ≥ 95th percentile nor waist circumference>95th percentile was significant.

CONCLUSIONS

Children and youth with NC>95th percentile for age and sex have significantly increased risk of OSA. This effect is significant in males ≥ 12 years, whereas BMI is not. NC percentile may be an additional screening tool for OSA in children and youth.

Does neck-to-waist ratio predict obstructive sleep apnea in children?

OBJECTIVES

Central adiposity and large neck circumference are associated with obstructive sleep apnea (OSA) in adults but have not been evaluated in children as predictors of OSA. Study objectives were to determine whether (1) anthropometric measures including neck-to-waist ratio are associated with OSA in older children; (2) body fat distribution, measured by neck-to-waist ratio, is predictive of OSA in overweight/obese children.

METHODS

Cross-sectional study involving children 7-18 years scheduled to undergo polysomnography at a tertiary care children's hospital. OSA was defined as total apnea-hypopnea index > 5 events/h and/or obstructive apnea index > 1 event/h. Recursive partitioning was used to select candidate predictors of OSA from: age, sex, height and weight percentile, body mass index (BMI) z-score, neck-to-waist ratio, tonsil size, and Mallampati score. These were then evaluated using log binomial models and receiver operator characteristic analysis.

RESULTS

Two hundred twenty-two participants were included; 133 (60%) were overweight/obese, 121 (55%) male,47 (21%) had OSA. Neck-to-waist ratio (relative risk [RR] 1.97 per 0.1 units, 95% CI 1.48 to 2.84) and BMI z-score (RR 1.63 per unit, 95% CI 1.30 to 2.05) were identified as independent predictors of OSA. Considering only overweight/obese children, neck-to-waist ratio (RR 2.16 per 0.1 units, 95% CI 1.79 to 2.59) and BMI z-score (RR 2.02 per unit, 95% CI 1.25 to 3.26) also independently predicted OSA. However, in children not overweight/obese, these variables were not predictive of OSA.

CONCLUSIONS

Neck-to-waist ratio, an index of body fat distribution, predicts OSA in older children and youth, especially in those who were overweight/obese.

Creation of a reference dataset of neck sizes in children: standardizing a potential new tool for prediction of obesity-associated diseases?

Background

Neck circumference (NC), is an emerging marker of obesity and associated disease risk, but is challenging to use as a screening tool in children, as age and sex standardized cutoffs have not been determined. A population-based sample of NC in Canadian children was collected, and age- and sex-specific reference curves for NC were developed.

Methods

NC, waist circumference (WC), weight and height were measured on participants aged 6–17 years in cycle 2 of the Canadian Health Measures Survey. Quantile regression of NC versus age in males and females was used to obtain NC percentiles. Linear regression was used to examine association between NC, body mass index (BMI) and WC. NC was compared in healthy weight (BMI < 85^th percentile) and overweight/obese (BMI > 85^th percentile) subjects.

Results

The sample included 936 females and 977 males. For all age and sex groups, NC was larger in overweight/obese children (p < 0.0001). For each additional unit of BMI, average NC in males was 0.49 cm higher and in females, 0.43 cm higher. For each additional cm of WC, average NC in males was 0.18 cm higher and in females, 0.17 cm higher.

Conclusion

This study presents the first reference data on Canadian children’s NC. The reference curves may have future clinical applicability in identifying children at risk of central obesity-associated conditions and thresholds associated with disease risk.

Impact of insufficient sleep on total daily energy expenditure, food intake, and weight gain

Insufficient sleep is associated with obesity, yet little is known about how repeated nights of insufficient sleep influence energy expenditure and balance. We studied 16 adults in a 14- to 15-d-long inpatient study and quantified effects of 5 d of insufficient sleep, equivalent to a work week, on energy expenditure and energy intake compared with adequate sleep. We found that insufficient sleep increased total daily energy expenditure by ∼5%; however, energy intake--especially at night after dinner--was in excess of energy needed to maintain energy balance. Insufficient sleep led to 0.82 ± 0.47 kg (±SD) weight gain despite changes in hunger and satiety hormones ghrelin and leptin, and peptide YY, which signaled excess energy stores. Insufficient sleep delayed circadian melatonin phase and also led to an earlier circadian phase of wake time. Sex differences showed women, not men, maintained weight during adequate sleep, whereas insufficient sleep reduced dietary restraint and led to weight gain in women. Our findings suggest that increased food intake during insufficient sleep is a physiological adaptation to provide energy needed to sustain additional wakefulness; yet when food is easily accessible, intake surpasses that needed. We also found that transitioning from an insufficient to adequate/recovery sleep schedule decreased energy intake, especially of fats and carbohydrates, and led to -0.03 ± 0.50 kg weight loss. These findings provide evidence that sleep plays a key role in energy metabolism. Importantly, they demonstrate physiological and behavioral mechanisms by which insufficient sleep may contribute to overweight and obesity.

Addressing obstructive sleep apnea in the emergency department

BACKGROUND

Obstructive sleep apnea (OSA) is a prevalent, serious disease that is under-recognized and under-treated. It results from a combination of increased pharyngeal collapsibility and impaired compensatory pharyngeal muscle dilator activity. OSA causes serious morbidity and mortality. OSA is also a public health problem in that it is an independent cause of car crashes, at great cost to society in dollars and lives. OSA is conservatively estimated to affect 2-4% of Americans; however, recent estimates are much higher.

OBJECTIVES

To educate emergency physicians on the pathophysiology, epidemiology, diagnosis, and management of OSA and discuss diagnostic approaches and recommendations that can be made from the emergency department (ED).

DISCUSSION

Emergency physicians can play an important role in the recognition and referral of patients at risk for OSA. A focused history and physical examination or the use of a structured evaluation can identify patients at risk for OSA. In addition to referring patients at risk for OSA for further diagnostic work-up, emergency physicians can offer recommendations such as weight loss, moderation of alcohol use and certain medications, and smoking cessation.

CONCLUSION

OSA is a common disease in the United States that is under-recognized and under-treated. ED patients who do not regularly see a primary care provider or have no primary care provider are particularly at risk for undiagnosed OSA. Emergency physicians can play an important role in recognizing patients at risk for OSA, referring them for further diagnostic work-up, and offering recommendations from the ED.

The relationship among registered nurses' weight status, weight loss regimens, and successful or unsuccessful weight loss

PURPOSE

To investigate relationships between body mass index (BMI), personality type, weight loss regimens, and successful or unsuccessful weight loss.

DATA SOURCES

Seven hundred and twenty-one registered nurses (RNs) were recruited from the American Academy of Nurse Practitioners, the membership of a nursing honor society, and RNs at a large state university. Participants completed the Myers-Briggs Type Indicator (MBTI), a demographic survey (age, gender, height, weight, ethnicity, education status, disability, shift work hours, and prescription medication use), and questions related to their weight status, weight loss attempts, and motivation.

CONCLUSIONS

RNs who had a lower BMI were more successful in losing weight than RNs who had a higher BMI. They were also more successful in their weight loss attempts if they did not use a diet regimen.

IMPLICATIONS FOR PRACTICE

RNs who were successful in losing weight did not use a specified dietary regimen.

Inter- and intra-rater reliability of neck circumference measurements in children

RATIONALE

Increased neck circumference is a risk factor for obstructive sleep apnea in adults. With rising obesity prevalence in children, it may be an important identifier of obstructive sleep apnea in children. The reliability of measuring neck circumference in children has not been systematically evaluated.

OBJECTIVE

To determine the inter- and intra-rater reliability of neck circumference measurements in children aged 2-16 years.

METHODS

Children aged 2-16 years with limb fractures were recruited. Neck circumference was measured by three investigators each using two separate unmarked paper tapes in the 2-5 year age group (N = 43), and three separate tapes in the 6-10 and 11-16 year age groups (N = 18 and 40).

RESULTS

Neck circumference measurements showed excellent inter-rater reliability for children 6-10 and 11-16 years (ICC = 0.952 and 0.989). Substantial variation was observed for the 2-5 year age group (ICC = 0.701). Good intra-rater reliability was demonstrated for the three groups (ICC range: 0.776, 0.950). Repeatability coefficients were 2.5-3.4 cm in the youngest age group and were 1.2-1.4 cm in the 6-16 year age group.

CONCLUSION

In children 6-16 years old, neck circumference shows very good inter and good intra-rater reliability. Multiple measurements are not required for precision and reliability.