Changes and variability in high levels of low-density lipoprotein cholesterol among children

Establishing non-fasting reference values for plasma lipids levels based on age, sex, and puberty stage in a French-Canadian pediatric population

BACKGROUND

Dyslipidemias, including familial hypercholesterolemia (FH), are a significant risk factor for cardiovascular diseases. FH is a genetic disorder resulting in elevated levels of low-density lipoprotein cholesterol (LDL-C) and an increased probability of early cardiovascular disorders. Heterozygous familial hypercholesterolemia (HeFH) is the most common form, affecting approximately 1 in 250 individuals worldwide, with a higher prevalence among the French-Canadian population. Childhood is a critical period for screening risk factors, but the recommendation for non-fasting screening remains controversial due to a lack of specific reference values for this state. This study aims to establish reference values for lipid levels in non-fasting children from Sherbrooke, Quebec, Canada, that will be specific for sex, age, and pubertal stages.

METHODS

Blood samples and corresponding anthropometric data were collected from 356 healthy children aged from 6 to 13. They were categorized either into two age groups: Cohort 6-8 and Cohort 9-13, or into pubertal stages. Reference values, specifically the 2.5th, 5th, 10th, 50th, 90th, 95th, and 97.5th percentiles were determined using the CLSI C28-A3 guidelines.

RESULTS

Lipid profiles did not significantly differ between sexes, except for higher levels of high-density lipoprotein (HDL-C) in boys within Cohort 6-8. HDL-C levels significantly increased, while LDL-C and non-HDL-C levels significantly decreased in both sexes with age. Non-fasting age- and pubertal stages-specific reference values were established.

CONCLUSION

This study established reference intervals for lipid markers in non-fasting state within the pediatric French-Canadian population. These findings could be used in dyslipidemia screening in daily practice.

Tracking of serum lipids in healthy children on a year-to-year basis

OBJECTIVES

To assess the stability of lipid profiles throughout childhood and evaluate their onset and dynamic.

MATERIALS AND METHODS

Lipid markers were longitudinally measured in more than 1300 healthy children from the LIFE Child study (Germany) and categorized into normal, at-risk, or adverse. Year-to-year intra-person persistence of the categories during follow-ups was examined and Pearson's correlation coefficient was calculated.

RESULTS

We found strong positive correlations for TC, LDL-C and ApoB (r > 0.75, p < 0.001) from the age of four years. Correlations were lowest during the first two years of life. Most children with normal levels also had normal levels the following year. Children with at-risk levels showed a tendency towards normal levels at the follow-up visit. Adverse levels of TC, LDL-C, ApoB (all ages), and HDL-C (from age 15) persisted in more than half of the affected children. Age-dependent patterns of stability were most pronounced and similar for TC, LDL-C, and ApoB.

CONCLUSIONS

Normal levels of serum lipids show high stability and adverse levels stabilized in early childhood for TC, LDL, and ApoB. At-risk and adverse levels of TC, LDL-C or ApoB may warrant further or repeated diagnostic measurements with regards to preventing CVD in the long run.

Age, maturation and serum lipid parameters: findings from the German Health Survey for Children and Adolescents

Background

Recommendations on preventive lipid screening among children and adolescents remain controversial. The aim of the study was to assess age and puberty-related changes in serum lipids, including total cholesterol (TC), and high-density (HDL-C) and non-high-density lipoprotein cholesterol (Non-HDL-C).

Methods

Using cross-sectional data from the National Health Interview and Examination Survey for Children and Adolescents in Germany (KiGGS 2003–2006; N = 13,676; 1–17 years), changes in distributions of serum lipids were visualized according to sex, age and maturation. Youth aged 10–17 years were classified as prepubescent, early/mid-puberty, and mature/advanced puberty. Multiple linear regressions were used to quantify the impact of pubertal stage on serum lipid levels, adjusted for potential confounding factors.

Results

Among children 1–9 years mean serum lipid measures increased with age, with higher mean TC and Non-HDL-C among girls than boys. Among children 10–17 years, advanced pubertal stage was independently related to lower lipid measures. Adjusted mean TC, HDL-C and Non-HDL-C was 19.4, 5.9 and 13.6 mg/dL lower among mature/advanced puberty compared to prepubescent boys and 11.0, 4.0 and 7.0 mg/dL lower in mature/advanced puberty compared to prepubescent girls.

Conclusions

Lipid concentrations undergo considerable and sex-specific changes during physical growth and sexual maturation and significantly differ between pubertal stages. Screening recommendations need to consider the fluctuations of serum lipids during growth and sexual maturation.

Nonlinear model for the carotid artery disease 10-year risk prediction by fusing conventional cardiovascular factors to carotid ultrasound image phenotypes: A Japanese diabetes cohort study

MOTIVATION

This study presents a novel nonlinear model which can predict 10-year carotid ultrasound image-based phenotypes by fusing nine traditional cardiovascular risk factors (ethnicity, gender, age, artery type, body mass index, hemoglobin A1c, hypertension, low-density lipoprotein, and smoking) with five types of carotid automated image phenotypes (three types of carotid intima-media thickness (IMT), wall variability, and total plaque area).

METHODOLOGY

Two-step process was adapted: First, five baseline carotid image-based phenotypes were automatically measured using AtheroEdge^™ (AtheroPoint^™ , CA, USA) system by two operators (novice and experienced) and an expert. Second, based on the annual progression rates of cIMT due to nine traditional cardiovascular risk factors, a novel nonlinear model was adapted for 10-year predictions of carotid phenotypes.

RESULTS

Institute review board (IRB) approved 204 Japanese patients' left/right common carotid artery (407 ultrasound scans) was collected with a mean age of 69 ± 11 years. Age and hemoglobin were reported to have a high influence on the 10-year carotid phenotypes. Mean correlation coefficient (CC) between 10-year carotid image-based phenotype and age was improved by 39.35% in males and 25.38% in females. The area under the curves for the 10-year measurements of five phenotypes IMT_ave10yr , IMT_max10yr , IMT_min10yr , IMTV_10yr , and TPA_10yr were 0.96, 0.94, 0.90, 1.0, and 1.0. Inter-operator variability between two operators showed significant CC (P < 0.0001).

CONCLUSIONS

A nonlinear model was developed and validated by fusing nine conventional CV risk factors with current carotid image-based phenotypes for predicting the 10-year carotid ultrasound image-based phenotypes which may be used risk assessment.

Which Amount of BMI-SDS Reduction Is Necessary to Improve Cardiovascular Risk Factors in Overweight Children?

CONTEXT

Knowing the changes of cardiovascular risk factors (CRFs) in relation to weight loss would be helpful to advise overweight children and their parents and to decide whether drugs should be prescribed in addition to lifestyle intervention.

OBJECTIVE

The objective of the study was to determine the body mass index (BMI)-SD score (SDS) reduction to improve CRFs in overweight children.

DESIGN

This was a prospective observation study.

SETTING

The study was conducted at a specialized outpatient obesity clinic.

PATIENTS

A total of 1388 overweight children (mean BMI 27.9 ± 0.1 kg/m(2), mean age 11.4 ± 0.1 y, 43.8% male, 45.5% prepubertal) participated in the study.

INTERVENTION

The study included a 1-year lifestyle intervention.

MAIN OUTCOME MEASURES

We studied changes of blood pressure (BP), fasting high-density lipoprotein- and low-density lipoprotein-cholesterol, triglycerides, glucose, and homeostasis model assessment (HOMA) of insulin resistance index. Change of weight status was determined by δBMI-SDS based on the recommended percentiles of the International Task Force of Obesity.

RESULTS

BMI-SDS change was associated with a significant improvement of all CRFs except fasting glucose and low-density lipoprotein-cholesterol after adjusting for multiple confounders such as baseline CRFs, age, gender, BMI, pubertal stage, and its changes. BMI-SDS reduction of 0.25-0.5 was related to a decrease of systolic blood pressure (BP) (-3.2 ± 1.4 mm Hg), diastolic BP (-2.2 ± 1.1 mm Hg), triglycerides (-6.9 ± 5.8 mg/dL), HOMA (-0.5 ± 0.3), and triglyceride/high-density lipoprotein)-cholesterol (-0.3 ± 0.2), whereas high-density lipoprotein (HDL)-cholesterol increased (+1.3 ± 1.2 mg/dL). A reduction of greater than 0.5 BMI-SDS led to more pronounced improvement (systolic BP -6.0± 1.3 mm Hg, diastolic BP -5.1 ± 1.3 mm Hg, triglycerides -16.4 ± 7.1 mg/dL, HDL-cholesterol +1.6 ± 1.5 mg/dL, HOMA -0.9 ± 0.3). Per 0.1 BMI-SDS reduction in systolic BP (-1.0 mm Hg), diastolic BP (-0.8 mm Hg), triglycerides (-2.3 mg/dL), HOMA (-0.2), and triglyceride/HDL-cholesterol (-0.5) decreased significantly, whereas HDL-cholesterol (0.2 mg/dL) increased significantly in linear regression analyses and accounted for multiple confounders.

CONCLUSIONS

A BMI-SDS reduction of 0.25 or greater significantly improved hypertension, hypertriglyceridemia, and low HDL-cholesterol, whereas a BMI-SDS greater than 0.5 doubled the effect.

The use of measures of obesity in childhood for predicting obesity and the development of obesity-related diseases in adulthood: a systematic review and meta-analysis

BACKGROUND

It is uncertain which simple measures of childhood obesity are best for predicting future obesity-related health problems and the persistence of obesity into adolescence and adulthood.

OBJECTIVES

To investigate the ability of simple measures, such as body mass index (BMI), to predict the persistence of obesity from childhood into adulthood and to predict obesity-related adult morbidities. To investigate how accurately simple measures diagnose obesity in children, and how acceptable these measures are to children, carers and health professionals.

DATA SOURCES

Multiple sources including MEDLINE, EMBASE and The Cochrane Library were searched from 2008 to 2013.

METHODS

Systematic reviews and a meta-analysis were carried out of large cohort studies on the association between childhood obesity and adult obesity; the association between childhood obesity and obesity-related morbidities in adulthood; and the diagnostic accuracy of simple childhood obesity measures. Study quality was assessed using Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) and a modified version of the Quality in Prognosis Studies (QUIPS) tool. A systematic review and an elicitation exercise were conducted on the acceptability of the simple measures.

RESULTS

Thirty-seven studies (22 cohorts) were included in the review of prediction of adult morbidities. Twenty-three studies (16 cohorts) were included in the tracking review. All studies included BMI. There were very few studies of other measures. There was a strong positive association between high childhood BMI and adult obesity [odds ratio 5.21, 95% confidence interval (CI) 4.50 to 6.02]. A positive association was found between high childhood BMI and adult coronary heart disease, diabetes and a range of cancers, but not stroke or breast cancer. The predictive accuracy of childhood BMI to predict any adult morbidity was very low, with most morbidities occurring in adults who were of healthy weight in childhood. Predictive accuracy of childhood obesity was moderate for predicting adult obesity, with a sensitivity of 30% and a specificity of 98%. Persistence of obesity from adolescence to adulthood was high. Thirty-four studies were included in the diagnostic accuracy review. Most of the studies used the least reliable reference standard (dual-energy X-ray absorptiometry); only 24% of studies were of high quality. The sensitivity of BMI for diagnosing obesity and overweight varied considerably; specificity was less variable. Pooled sensitivity of BMI was 74% (95% CI 64.2% to 81.8%) and pooled specificity was 95% (95% CI 92.2% to 96.4%). The acceptability to children and their carers of BMI or other common simple measures was generally good.

LIMITATIONS

Little evidence was available regarding childhood measures other than BMI. No individual-level analysis could be performed.

CONCLUSIONS

Childhood BMI is not a good predictor of adult obesity or adult disease; the majority of obese adults were not obese as children and most obesity-related adult morbidity occurs in adults who had a healthy childhood weight. However, obesity (as measured using BMI) was found to persist from childhood to adulthood, with most obese adolescents also being obese in adulthood. BMI was found to be reasonably good for diagnosing obesity during childhood. There is no convincing evidence suggesting that any simple measure is better than BMI for diagnosing obesity in childhood or predicting adult obesity and morbidity. Further research on obesity measures other than BMI is needed to determine which is the best tool for diagnosing childhood obesity, and new cohort studies are needed to investigate the impact of contemporary childhood obesity on adult obesity and obesity-related morbidities.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42013005711.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Changes in Fasting Lipids during Puberty

OBJECTIVE

To describe longitudinal changes in plasma lipid levels and pubertal stage in youths from age 8-18 years, in Project HeartBeat!

STUDY DESIGN

Fasting blood samples and pubertal stage, using physical assessment of secondary sex characteristics, were obtained every 4 months for up to 4 years in a mixed longitudinal study of 633 children (49.1% female, 20.1% black), initially aged 8, 11, and 14 years. Total cholesterol, low density lipoprotein-cholesterol, high density lipoprotein-cholesterol, triglycerides (TG), and nonhigh density lipoprotein-cholesterol measurements were obtained. Data were collected from 1991-1995.

RESULTS

Pubertal stage correlations with age varied among all race-sex groups (range, r = 0.61-0.70), and a given pubertal stage could represent a range of 5 years or more of chronological age. Throughout puberty, levels of total cholesterol, low density lipoprotein-cholesterol, and nonhigh density lipoprotein-cholesterol decreased, TG in males increased, and high density lipoprotein-cholesterol and TG in females showed no changes. Within a given pubertal stage, plasma lipid levels tended to differ by race, sex, or both.

CONCLUSIONS

Lipid levels change markedly by pubertal stage, and patterns differ by sex and race. Chronological age ranges widely within a given pubertal stage and is an insensitive indicator of pubertal stage and the related changes in lipid levels. Pubertal development should be considered when determining screening criteria to identify youths with adverse blood lipid levels.

Cholesterol curves to identify population norms by age and sex in healthy weight children

OBJECTIVE

Develop clinically applicable charts of lipid values illustrating fluctuations throughout childhood and by sex among healthy weight children.

METHODS

The National Health and Nutrition Examination Survey (1999-2008) was used to estimate total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides by age and sex in healthy weight children age 3 to 17 years. Using LMS procedures, the authors created smoothed curves demonstrating population-based 50th percentile for age and the 75th and 95th percentiles.

RESULTS

The curves were based on 7681 children meeting inclusion criteria. Total cholesterol, HDL, and LDL demonstrated peaks at approximately 8 to 12 years for boys. Similar peaks were evident for girls at slightly younger ages, approximately 7 to 11 years. Triglycerides showed peaks for girls, but values were similar across ages for boys.

CONCLUSIONS

The use of fixed lipid value cutoffs in established guidelines regardless of age or sex likely mislabels many children as abnormal. The authors' charts may allow for a more nuanced interpretation based on population norms.

Fasting might not be necessary before lipid screening: a nationally representative cross-sectional study

BACKGROUND

There are barriers to fasting lipid screening for at-risk children. Results of studies in adults have suggested that lipid testing might be reliably performed without fasting.

OBJECTIVE

To examine population-level differences in pediatric lipid values based on length of fast before testing.

METHODS

We used the National Health and Nutrition Examination Survey (1999-2008) to examine total cholesterol (TC), HDL (high-density lipoprotein), LDL (low-density lipoprotein), and triglyceride cholesterol components on the basis of the period of fasting. Young children fasted for varying times before being tested, and children older than 12 years were asked to fast; however, adherence was variable. We used ordinary least-squares regression to test for differences in lipid values that were based on fasting times, controlling for weight status, age, race, ethnicity, and gender.

RESULTS

TC, HDL, LDL, or triglyceride values were available for 12 744 children. Forty-eight percent of the TC and HDL samples and 80% of the LDL and triglyceride samples were collected from children who had fasted ≥ 8 hours. Fasting had a small positive effect for TC, HDL, and LDL, resulting in a mean value for the sample that was 2 to 5 mg/dL higher with a 12-hour fast compared with a no-fast sample. Fasting time had a negative effect on triglycerides (β = -0.859; P = .02), which resulted in values in the fasting group that were 7 mg/dL lower.

DISCUSSION

Comparison of cholesterol screening results for a nonfasting group of children compared with results for a similar fasting group resulted in small differences that are likely not clinically important. Physicians might be able to decrease the burden of childhood cholesterol screening by not requiring prescreening fasting for these components.