Comparing US paediatric and adult weight classification at the transition from late teenage to young adulthood.

BACKGROUND: Although paediatric growth charts are recommended for weight assessment prior to age 20, many teenagers transition earlier to adult care where absolute body mass index (BMI) is used. This study examines concordance of weight classification in older teenagers using paediatric percentiles and adult thresholds. METHODS: BMI from 23 640 US teens ages 18-19 years were classified using paediatric BMI percentile criteria for underweight (< 5th), normal (5th to < 85th), overweight (85th to < 95th), obesity (≥ 95th) and severe obesity (≥ 120% × 95th percentile) and adult BMI (kg m(-2) ) criteria for underweight (< 18.5), normal (18.5-24.9), overweight (25-29.9) and obesity: class I (30-34.9), class II (35-39.9) and class III (≥ 40). Concordance was examined using the kappa (κ) statistic. Blood pressure (BP) from the same visit was classified hypertensive for BP ≥ 140/90. RESULTS: The majority of visits (72.8%) occurred in adult primary care. Using paediatric/adult criteria, 3.4%/5.2% were underweight, 66.6%/58.8% normal weight, 15.7%/21.7% overweight, 14.3%/14.3% obese and 4.9%/6.0% severely/class II-III obese, respectively. Paediatric and adult classification for underweight, normal, overweight and obesity were concordant for 90.3% (weighted κ 0.87 [95% confidence interval, 0.87-0.88]). For severe obesity, BMI ≥ 120% × 95th percentile showed high agreement with BMI ≥ 35 kg m(-2) (κ 0.89 [0.88-0.91]). Normal-weight males and moderately obese females by paediatric BMI percentile criteria who were discordantly classified into higher adult weight strata had a greater proportion with hypertensive BP compared with concordantly classified counterparts. CONCLUSIONS: Strong agreement exists between US paediatric BMI percentile and adult BMI classification for older teenagers. Adult BMI classification may optimize BMI tracking and risk stratification during transition from paediatric to adult care.

Visceral adipose tissue measured by DXA correlates with measurement by CT and is associated with cardiometabolic risk factors in children.

BACKGROUND: Visceral adipose tissue (VAT) generally demonstrates a stronger relationship with cardiometabolic risk factors than total body fat or subcutaneous adipose tissue. OBJECTIVES: The purpose of this study was to compare VAT estimated in children by total volume dual-energy X-ray absorptiometry (DXA) with a gold standard measurement, single slice (L4-L5) computed tomography (CT). METHODS: A total of 329 (152 females, 177 males) children ages 6-18 years (mean age 12.3 ± 3.6) and with average body mass index percentile of 54.9% (3-99%) had their VAT estimated by both CT and DXA. Linear association between methods was measured using Pearson's correlation. Multiple linear regressions compared the associations between cardiometabolic risk factors and both CT-VAT and DXA-VAT, respectively. RESULTS: In children, DXA-VAT was correlated significantly with CT-VAT, with a stronger relationship in overweight and obese children. Multiple regression analysis showed that both estimates of VAT were significantly associated with lipids and insulin sensitivity, measured by euglycaemic-hyperinsulinaemic clamp. Additionally, DXA-VAT was associated with diastolic blood pressure, homeostasis model of insulin resistance and fasting insulin, but CT-VAT was not. CONCLUSION: In children, total volume DXA-VAT and single slice CT-VAT are significantly correlated and each demonstrates similar associations with cardiometabolic risk factors. This suggests that DXA is a useful and valid method for estimation of VAT in children.

The relative contributions of the abdominal visceral and subcutaneous fat depots to cardiometabolic risk in youth.

The aim of this study was to evaluate the association of abdominal visceral and subcutaneous fat, independent of total body fat, with cardiometabolic risk factors and insulin resistance among youth. Visceral and subcutaneous fat, percentage total body fat, insulin resistance (adjusted for lean body mass: Mlbm), blood pressure, glucose, insulin and lipids were obtained in 472 youth ages 6-18 years. Linear regression, adjusted for age, sex, race, Tanner stage and percentage total body fat, was used to evaluate associations of visceral and subcutaneous fat with cardiometabolic risk factors. Visceral fat was associated inversely with Mlbm (P = 0.003) and positively with fasting insulin (P = 0.002) and triglycerides (P = 0.002). Visceral fat levels above the mean were associated inversely with high-density lipoprotein (HDL) cholesterol (P = 0.002), and positively with systolic blood pressure (P < 0.0001) and non-HDL cholesterol (P < 0.0001). Subcutaneous fat was associated inversely with Mlbm (P = 0.003) and HDL cholesterol (P < 0.05), and positively with fasting glucose (P < 0.05), fasting insulin (P = 0.0003), systolic blood pressure (P = 0.005) and triglycerides (P = 0.003). Subcutaneous fat levels above the mean were associated with non-HDL cholesterol (P = 0.0002). These findings suggest that there may be a threshold level of visceral and subcutaneous fat (regardless of total body fat), that when exceeded in childhood, is more likely to be associated with many cardiometabolic risk factors. Triglycerides and insulin resistance appear to be associated with these fat depots at even lower thresholds of abdominal adiposity.

Prevalence of obesity and extreme obesity in children aged 3-5 years.

BACKGROUND: Early childhood adiposity may have significant later health effects. This study examines the prevalence and recognition of obesity and severe obesity among preschool-aged children. METHODS: The electronic medical record was used to examine body mass index (BMI), height, sex and race/ethnicity in 42,559 children aged 3-5 years between 2007 and 2010. Normal or underweight (BMI < 85th percentile); overweight (BMI 85th-94th percentile); obesity (BMI ≥ 95th percentile); and severe obesity (BMI ≥ 1.2 × 95th percentile) were classified using the 2000 Centers for Disease Control and Prevention growth charts. Provider recognition of elevated BMI was examined for obese children aged 5 years. RESULTS: Among 42,559 children, 12.4% of boys and 10.0% of girls had BMI ≥ 95th percentile. The prevalence was highest among Hispanics (18.2% boys, 15.2% girls), followed by blacks (12.4% boys, 12.7% girls). A positive trend existed between increasing BMI category and median height percentile, with obesity rates highest in the highest height quintile. The prevalence of severe obesity was 1.6% overall and somewhat higher for boys compared with girls (1.9 vs. 1.4%, P < 0.01). By race/ethnicity, the highest prevalence of severe obesity was seen in Hispanic boys (3.3%). Among those aged 5 years, 77.9% of obese children had provider diagnosis of obesity or elevated BMI, increasing to 89.0% for the subset with severe obesity. CONCLUSIONS: Obesity and severe obesity are evident as early as age 3-5 years, with race/ethnic trends similar to older children. This study underscores the need for continued recognition and contextualization of early childhood obesity in order to develop effective strategies for early weight management.

Relation of chemokines to BMI and insulin resistance at ages 18-21.

OBJECTIVE: In obesity, adipose tissue becomes a significant source of chemokines and inflammatory cytokines that are associated with chronic systemic low-grade inflammation and may lead to insulin resistance. Studies in children have mainly focused on inflammatory cytokines and there are limited data for chemokines in adolescents and young adults. We studied the relation of chemokines to cardiovascular (CV)-risk factors, insulin resistance and adipocytokines in 18-21-year-old individuals. SUBJECTS AND DESIGN: Cross-sectional data collected in a cohort originally enrolled at mean age 13, with data for the present study obtained from 252 examined at age 18.7±0.1 years. METHODS: Multiple linear regression models were used to analyze the associations among chemokines (monocyte chemotactic protein-1, macrophage inflammatory protein-1ß (MIP-1ß), visfatin and interleukin-8 (IL-8)) and between chemokines and body mass index (BMI), glucose, lipids, blood pressure (BP), insulin resistance (euglycemic hyperinsulinemic clamp) and adipocytokines (IL-6, TNF-α and adiponectin). RESULTS: Chemokine levels were significantly intercorrelated. Significant associations (P<0.05) with adjustment for age, race and sex included: MIP-1ß with waist circumference and IL-6, IL-8 with systolic BP and visfatin with IL-6. No other significant relations were found between the chemokines and the other variables. Further adjustment for BMI did not alter these conclusions. CONCLUSION: Considered in the context of prior studies in children and adults, these results suggest that in large part, the association between chemokines and CV risk or inflammatory factors does not appear to develop until adult life.

Development of associations among central adiposity, adiponectin and insulin sensitivity from adolescence to young adulthood.

OBJECTIVE: To examine associations of central adiposity, serum adiponectin and clamp-derived insulin sensitivity in a single longitudinal cohort from early adolescence to young adulthood. METHODS: The cohort was examined three times at mean ages 15 years (n = 308), 19 years (n = 218) and 22 years (n = 163). Insulin sensitivity was measured with the euglycaemic hyperinsulinaemic clamp. Circulating adiponectin was measured by enzyme-linked immunosorbent assay. Computed tomography scans were used at mean age 22 to compute subcutaneous and visceral abdominal fat volume. Partial Pearson correlations and linear regression were used to examine cross-sectional associations at each examination. RESULTS: The moderate negative correlation between waist circumference and adiponectin was significant and essentially unchanged from mean age 15 (-0.32, P < 0.0001) to mean age 22 (-0.29, P < 0.002), whereas the negative correlation between waist circumference and insulin sensitivity and the positive correlation between adiponectin and insulin sensitivity increased steadily in magnitude to mean age 22 (-0.29, P = 0.0002; and 0.32, P < 0.0001, respectively). In regression models including both visceral and subcutaneous fat, only visceral fat was significantly associated with insulin sensitivity, while only subcutaneous fat was nearly significantly associated with adiponectin. CONCLUSIONS: This study shows that the significant negative relationship between waist circumference and adiponectin predated the development of significant relationships between insulin sensitivity and both waist circumference and adiponectin. It also shows that adiponectin is more closely related to subcutaneous fat and insulin sensitivity is more closely related to visceral fat in young adults.

The relationship of retinal vessel diameter to changes in diabetic nephropathy structural variables in patients with type 1 diabetes.

AIMS/HYPOTHESIS: We examined whether retinal vessel diameter in persons with type 1 diabetes mellitus is associated with changes in subclinical anatomical and functional indicators of diabetic nephropathy. METHODS: Persons with type 1 diabetes mellitus had gradable fundus photographs and renal biopsy data at baseline and 5-year follow-up (n = 234). Retinal arteriolar and venular diameters were measured at baseline and follow-up. Central retinal arteriole equivalent (CRAE) and central retinal venule equivalent (CRVE) were computed. Baseline and 5-year follow-up renal structural variables were assessed by masked electron microscopic morphometric analyses from percutaneous renal biopsy specimens. Variables assessed included: mesangial fractional volume, glomerular basement membrane width, mesangial matrix fractional volume and glomerular basement membrane width composite glomerulopathy index. RESULTS: While controlling for other covariates, baseline CRAE was positively associated with change in the glomerulopathy index over the 5-year period. Change in CRAE was inversely related to a change in mesangial matrix fractional volume and abnormal mesangial matrix fractional volume, while change in CRVE was directly related to change in the volume fraction of cortex that was interstitium [Vv((Int/cortex))] over the 5-year period. Baseline CRAE or CRVE or changes in these diameters were not related to changes in other anatomical or functional renal endpoints. CONCLUSIONS/INTERPRETATION: Independently of other factors, baseline CRAE correlated with changes in glomerulopathy index, a composite measure of extracellular matrix accumulation in the mesangium and glomerular basement membrane. A narrowing of the CRAE was related to mesangial matrix accumulation. Changes in CRVE were related to changes in Vv((Int/cortex),) a measure of interstitial expansion in persons with type 1 diabetes mellitus.

Serum phospholipid and cholesteryl ester fatty acids and estimated desaturase activities are related to overweight and cardiovascular risk factors in adolescents.

AIM/HYPOTHESIS: The objective of this study was to describe the relation of serum fatty acids and desaturase activity (DA) to overweight, insulin sensitivity and cardiovascular disease (CVD) risk factors in adolescents. METHODS: The relations of % serum phospholipid (PL) and cholesteryl ester (CE) fatty acids and estimated DA with CVD risk factors were examined in 264 adolescents (average age 15 years). Fatty acids were determined by gas liquid chromotography. Surrogate measures of DA were expressed as ratios of serum fatty acids: Delta9 DA=16:0/16:1; Delta6 DA=20:3,n6/18:2,n6 (PL) or 18:3,n6/18:2,n6 (CE); and Delta5 DA=20:4,n6/20:3,n6. Spearman partial correlations of fatty acids (%) and DA ratios with CVD risk factors were reported, adjusting for age, sex, race, Tanner stage, energy intake and physical activity. RESULTS: Overweight adolescents compared to normal weight had more adverse levels of CVD risk factors, composition of PL and CE fatty acids in serum, and Delta6 DA and Delta5 DA ratios. Linoleic acid was inversely related to body mass index (BMI), waist circumference and triglycerides (P

Heritability and genetic correlations of insulin sensitivity measured by the euglycaemic clamp.

AIMS: Studies investigating genetic factors influencing insulin sensitivity/insulin resistance have measured this phenotype using a variety of methods. In this study, genetic correlations and heritability of insulin sensitivity measured using the euglycaemic hyperinsulinaemic clamp and related phenotypes were examined. METHODS: The study population included 818 non-diabetic individuals from 297 nuclear families. Genetic correlations and heritability estimates were calculated using variance components methods. RESULTS: Homeostasis model of insulin resistance (HOMA-IR) and fasting insulin were very highly phenotypically and genetically correlated (r = 0.99 and r = 0.99). HOMA-IR and insulin sensitivity measured with the euglycaemic clamp were only moderately genetically correlated (r = -0.53), suggesting that the two traits may be influenced, at least in part, by different genes. Heritabilities for fasting insulin (h2 = 0.36) and HOMA-IR (h2 = 0.38) were consistent with the published literature, but heritability for insulin sensitivity measured by the euglycaemic clamp was slightly lower than other published estimates (h(2) = 0.24). CONCLUSIONS: Because HOMA-IR (or fasting insulin) and insulin sensitivity measured with the euglycaemic clamp are not highly genetically correlated, they should not be used interchangeably in genetic studies. Given the very high correlations between fasting insulin and HOMA-IR, HOMA-IR does not offer any advantage over fasting insulin in analyses of insulin sensitivity in this population.

Comparison of body fatness measurements by BMI and skinfolds vs dual energy X-ray absorptiometry and their relation to cardiovascular risk factors in adolescents.

OBJECTIVE: To compare estimates of adiposity by dual emission X-ray absorptiometry (DXA), skinfolds and body mass index (BMI); and to evaluate the relation of these measures to cardiovascular risk in adolescents. DESIGN: In a cohort of adolescents participating in a longitudinal study of insulin resistance, Slaughter formulas were used to estimate adiposity from skinfolds and DXA was used to estimate adiposity as % body fat (%BF) and fat mass (FBM). BMI, blood pressure, lipids and insulin resistance were measured. SUBJECTS: Male and female, 11-17 y old (n=130). MEASUREMENTS: To compare DXA with two office-based methods of assessing fatness and cardiovascular risk. RESULTS: Slaughter estimates were highly correlated with DXA (%BF r=0.92, P=0.0001; FBM r=0.96, P=0.0001). Correlations were similar in heavy and thin children. BMI was also highly correlated with DXA (%BF r=0.85, P=0.0001; FBM r=0.95, P=0.0001), and these relations were stronger in heavy than thin children. BMI and the Slaughter formulas were similar to DXA in their relations to cardiovascular risk factors. CONCLUSIONS: Adiposity by BMI and Slaughter formulas are highly correlated with DXA and similarly related to cardiovascular risk factors. BMI is easy to obtain and is an acceptable method for initial office estimation of body fatness. BMI and skinfolds compare well with DXA in predicting adverse cardiovascular risk profile.

Insulin resistance (metabolic) syndrome in children.

The insulin resistance (metabolic) syndrome (IRS), also known as syndrome X, is characterized by a clustering of factors associated with cardiovascular risk (obesity, impaired glucose metabolism, hypertension, and dyslipidemia). As reported from the third National Health and Nutrition Examination survey, the IRS is present in approximately 24% of adults in the United States and is strongly associated with coronary heart disease, stroke, type 2 diabetes, and all-cause mortality. Of equal importance, it is now clear that the origins of the IRS extend back into childhood (the IRS is found in approximately 4-10% of children and adolescents) and that the high prevalence of adult IRS is strongly linked to the development of cardiovascular risk during childhood and tracking of the components of the IRS into adulthood. The goal of this review is to present a summary of the currently available information on the IRS in the pre-adult age group with reference to adult studies only when necessary for clarification. The review will specifically summarize insulin resistance in childhood; the important influence of obesity and, in particular, visceral fat, on insulin resistance and the IRS; differences between ethnic groups; relations to adipocytokines, inflammatory factors and oxidative stress; relations of hypertension and lipids to insulin resistance; familial factors; endocrine complications; and potential therapeutic effects from diet and physical activity. Despite the lesser amount of basic and clinical information on childhood IRS in comparison to information available from adult studies, there can now be little doubt that the adverse associations among risk factors comprising the IRS begin in childhood. The challenge is to identify etiologic relations and develop intervention strategies designed to reduce the increasing prevalence of type 2 diabetes and cardiovascular disease.

The culture of safety: results of an organization-wide survey in 15 California hospitals.

OBJECTIVE: To understand fundamental attitudes towards patient safety culture and ways in which attitudes vary by hospital, job class, and clinical status. DESIGN: Using a closed ended survey, respondents were questioned on 16 topics important to a culture of safety in health care or other industries plus demographic information. The survey was conducted by US mail (with an option to respond by Internet) over a 6 month period from April 2001 in three mailings. SETTING: 15 hospitals participating in the California Patient Safety Consortium. SUBJECTS: A sample of 6312 employees generally comprising all the hospital's attending physicians, all the senior executives (defined as department head or above), and a 10% random sample of all other hospital personnel. The response rate was 47.4% overall, 62% excluding physicians. Where appropriate, responses were weighted to allow an accurate comparison between participating hospitals and job types and to correct for non-response. MAIN OUTCOME MEASURES: Frequency of responses suggesting an absence of safety culture ("problematic responses" to survey questions) and the frequency of "neutral" responses which might also imply a lack of safety culture. Responses to each question overall were recorded according to hospital, job class, and clinician status. RESULTS: The mean overall problematic response was 18% and a further 18% of respondents gave neutral responses. Problematic responses varied widely between participating institutions. Clinicians, especially nurses, gave more problematic responses than non-clinicians, and front line workers gave more than senior managers. CONCLUSION: Safety culture may not be as strong as is desirable of a high reliability organization. The culture differed significantly, not only between hospitals, but also by clinical status and job class within individual institutions. The results provide the most complete available information on the attitudes and experiences of workers about safety culture in hospitals and ways in which perceptions of safety culture differ among hospitals and between types of personnel. Further research is needed to confirm these results and to determine how senior managers can successfully transmit their commitment to safety to the clinical workplace.

Association of physical activity with insulin sensitivity in children.

BACKGROUND: Physical activity (PA) has been shown to improve insulin resistance and other cardiovascular disease risk factors in normal and diabetic adults and in obese youth, but not in non-diabetic, normal-weight children. METHODS: Data from 357 non-diabetic children (10-16 y) were used to examine cross-sectional associations with PA. Insulin sensitivity was assessed with a euglycemic hyperinsulinemic clamp and expressed as M(ffm) (glucose utilization/kg of fat-free mass/min). RESULTS: Correlations were adjusted for age, sex, race and Tanner stage. PA was significantly correlated with fasting insulin and insulin sensitivity (r=-0.12, P=0.03 and r=0.13, P=0.001, respectively), more strongly in children with above-median systolic blood pressure (r=-0.17, P=0.03 and r=0.35, P=0.0001, respectively). Further adjustment for body mass index, body fat percentage, waist circumference or lipids did not alter these observations. CONCLUSIONS: Physical activity is correlated with lower fasting insulin and greater insulin sensitivity in childhood. These results are consistent with the hypothesis that increasing physical activity among youth may reduce the incidence of type 2 diabetes in children and adolescents.

Insulin resistance syndrome in childhood: associations of the euglycemic insulin clamp and fasting insulin with fatness and other risk factors.

OBJECTIVE: Our objective was to describe in children the relation of fatness and insulin resistance to the risk factors associated with the insulin resistance syndrome and to compare fasting insulin with the euglycemic insulin clamp as a measure of insulin resistance in children. STUDY DESIGN: This was a random selection of participants after blood pressure screening of 12,043 students in the fifth through eighth grades. Euglycemic insulin clamp studies with an insulin infusion rate of 1 mU/kg/min and a variable infusion of 20% glucose to maintain euglycemia, that is, plasma glucose at 5.6 mmol/L. Insulin sensitivity (M(lbm)) is defined as the amount of glucose required to maintain euglycemia (milligrams of glucose infused per kilogram lean body mass per minute). RESULTS: Body mass index was significantly correlated with fasting insulin and significantly inversely correlated with M(lbm). Fasting insulin was significantly correlated with systolic blood pressure in both sexes, all lipids, except high-density lipoprotein-cholesterol in males and triglycerides and high-density lipoprotein-cholesterol in females, but after adjustment was done for body mass index, it was significantly related only to triglycerides. M(lbm) was significantly correlated only with triglycerides and high-density lipoprotein-cholesterol, and this did not change after adjustment was done for body mass index. A clustering effect for the risk factors was seen in children in the lowest quartile of M(lbm) (highest degree of insulin resistance) compared with children in the highest quartile of M(lbm) (lowest degree of insulin resistance). CONCLUSIONS: As defined by M(lbm), there is an early association of insulin resistance, independent of body fat, with the risk factors. There is a significant relation between fasting insulin, as an estimate of insulin resistance, and the risk factors, but this is significantly influenced by body fatness. The clustering of risk factors according to level of M(lbm) suggests that adult cardiovascular disease is more likely to develop in children with the greatest degree of insulin resistance.

Prevalence of hypertension in junior high school-aged children: effect of new recommendations in the 1996 Updated Task Force Report.

The 1996 "Update on the 1987 Task Force Report on Blood Pressure in Children and Adolescents" adopted the fifth Korotkoff phase to define diastolic blood pressure and added height, in addition to age and gender, to develop new standards for blood pressure (BP) in children. The present study was performed to determine whether these changes altered the previously reported prevalence of hypertension in junior high school-aged children. Blood pressure screening was conducted in 19,452 fifth to eighth grade students. All students with a systolic blood pressure more than the 70th percentile had their BP measured a second time (rescreening). Using the 1996 criteria, systolic hypertension was found in 2.7% and diastolic hypertension in 2% after the screening. After the rescreening, systolic hypertension had fallen to 0.8% and diastolic hypertension to 0.4%. The prevalence of systolic hypertension was slightly higher and diastolic hypertension slightly lower than in 1987. These reports show that the overall prevalence of hypertension (1%) using the 1996 Updated Task Force criteria is similar to the prevalence using the original 1987 criteria. These results also confirm the importance of the Task Force recommendation that multiple BP measurements should be obtained before making a diagnosis of hypertension.