SARS-CoV-2 viral clearance and viral load kinetics in young children (1-6 years) compared to adults: Results of a longitudinal study in Germany.

Objective: To investigate SARS-COV-2 viral clearance and viral load kinetics in the course of infection in children aged 1-6 years in comparison with adults. Methods: Prospective cohort study of infected daycare children and staff and their close contacts in households from 11/2020 to 06/2021. Adult participants took upper respiratory tract specimen from themselves and/or their children, for PCR tests on SARS-CoV-2. Data on symptoms and exposure were used to determine the date of probable infection for each participant. We determined (a) viral clearance, and (b) viral load dynamics over time. Samples were taken from day 4-6 to day 16-18 after diagnosis of the index case in the respective daycare group (5 samples per participant). Results: We included 40 children (1-6 years) and 67 adults (18-77 years) with SARS-CoV-2 infection. Samples were available at a mean of 4.3 points of time per participant. Among the participants, the 12-day study period fell in different periods within the individual course of infection, ranging from day 5-17 to day 15-26 after assumed infection.Children reached viral clearance at a median of 20 days after assumed infection (95% CI 17-21 days, Kaplan-Meier Analysis), adults at 23 days (95% CI 20-25 days, difference not significant). In both children and adults, viral load decreased over time with trajectories of the mean viral load not being statistically different between groups. Kaplan-Meier calculations show that from day 15 (95% CI 13-15), 50% of all participants had a viral load <1 million copies/ml, i.e. were no longer infectious or negative. Conclusion: Children aged 1-6 and adults infected with SARS-CoV-2 (wild type and Alpha variant) did not differ significantly in terms of viral load kinetics and time needed to clear the virus. Therefore, containment measures are important also in the daycare settings as long as the pandemic continues.

Transmission of SARS-CoV-2 among children and staff in German daycare centres.

In daycare centres, the close contact of children with other children and employees favours the transmission of infections. The majority of children <6 years attend daycare programmes in Germany, but the role of daycare centres in the SARS-CoV-2 pandemic is unclear. We investigated the transmission risk in daycare centres and the spread of SARS-CoV-2 to associated households. 30 daycare groups with at least one recent laboratory-confirmed SARS-CoV-2 case were enrolled in the study (10/2020-06/2021). Close contact persons within daycare and households were examined over a 12-day period (repeated SARS-CoV-2 PCR tests, genetic sequencing of viruses, symptom diary). Households were interviewed to gain comprehensive information on each outbreak. We determined primary cases for all daycare groups. The number of secondary cases varied considerably between daycare groups. The pooled secondary attack rate (SAR) across all 30 daycare centres was 9.6%. The SAR tended to be higher when the Alpha variant was detected (15.9% vs. 5.1% with evidence of wild type). The household SAR was 53.3%. Exposed daycare children were less likely to get infected with SARS-CoV-2 than employees (7.7% vs. 15.5%). Containment measures in daycare programmes are critical to reduce SARS-CoV-2 transmission, especially to avoid spread to associated households.

Carotid Intima-Media Thickness Percentiles in Adolescence and Young Adulthood and Their Association With Obesity and Hypertensive Blood Pressure in a Population Cohort.

BACKGROUND: This study aimed to derive carotid intima media thickness (CIMT) percentiles from a population-based sample of adolescents and young adults using improved technology, standardization and quality control, and to investigate the association of CIMT with hypertensive blood pressure (BP) and obesity. METHODS: Four thousand seven hundred nine 14- to 28-year-old participants of the German KiGGS cohort 11-year follow-up, which was based on a nationwide population sample, had B-mode ultrasound CIMT measurement with semi-automated edge-detection and automatic ECG-gated real-time quality control. CIMT percentiles were estimated from far wall CIMT during 2 to 6 heart cycles using the GAMLSS statistical model. Hypertensive BP, overweight, obesity, and a risk score from added Z scores of triglycerides, total/HDL (high-density lipoprotein)-cholesterol ratio, and glycated hemoglobin were based on standardized measurements at baseline and follow-up. RESULTS: CIMT differed by sex at all ages, furthermore by age and height in a nonlinear fashion. Percentiles were estimated simultaneously by age and height. Hypertensive BP and obesity were associated cross-sectionally and longitudinally with a higher risk of CIMT ≥75th percentile in log-binomial regression models adjusted for age, sex, height, current smoking, and cardiovascular risk score. For CIMT ≥90th percentile, the relative risk effect estimates were consistently >1 but often had large confidence intervals including 1, largest adjusted relative risk 3.37 (95% CI, 1.41-8.04) for the combination of hypertensive BP and obesity at follow-up. CONCLUSIONS: Based on state-of-the-art measurements and statistical techniques, these population-based CIMT percentiles by sex, age and height add unbiased evidence for the association of subclinical atherosclerosis with hypertensive BP and obesity in the young.

SARS-CoV-2 Transmissibility Within Day Care Centers-Study Protocol of a Prospective Analysis of Outbreaks in Germany.

Introduction: Until today, the role of children in the transmission dynamics of SARS-CoV-2 and the development of the COVID-19 pandemic seems to be dynamic and is not finally resolved. The primary aim of this study is to investigate the transmission dynamics of SARS-CoV-2 in child day care centers and connected households as well as transmission-related indicators and clinical symptoms among children and adults. Methods and Analysis: COALA ("Corona outbreak-related examinations in day care centers") is a day care center- and household-based study with a case-ascertained study design. Based on day care centers with at least one reported case of SARS-CoV-2, we include one- to six-year-old children and staff of the affected group in the day care center as well as their respective households. We visit each child's and adult's household. During the home visit we take from each household member a combined mouth and nose swab as well as a saliva sample for analysis of SARS-CoV-2-RNA by real-time reverse transcription polymerase chain reaction (real-time RT-PCR) and a capillary blood sample for a retrospective assessment of an earlier SARS-CoV-2 infection. Furthermore, information on health status, socio-demographics and COVID-19 protective measures are collected via a short telephone interview in the subsequent days. In the following 12 days, household members (or parents for their children) self-collect the same respiratory samples as described above every 3 days and a stool sample for children once. COVID-19 symptoms are documented daily in a symptom diary. Approximately 35 days after testing the index case, every participant who tested positive for SARS-CoV-2 during the study is re-visited at home for another capillary blood sample and a standardized interview. The analysis includes secondary attack rates, by age of primary case, both in the day care center and in households, as well as viral shedding dynamics, including the beginning of shedding relative to symptom onset and viral clearance. Discussion: The results contribute to a better understanding of the epidemiological and virological transmission-related indicators of SARS-CoV-2 among young children, as compared to adults and the interplay between day care and households.

[Just method effects? Prevalences of underweight, overweight and obesity in children and adolescents according to the weighting factors and reference system used]. / Alles nur Methodeneffekte? Prävalenz von Untergewicht, Übergewicht und Adipositas bei Kindern und Jugendlichen in Abhängigkeit von Gewichtungsfaktoren und Referenzsystem.

BACKGROUND: The German Health Interview and Examination Survey for Children and Adolescents (KiGGS) is an important data source for assessing the occurrence of underweight, overweight and obesity in children and adolescents in Germany. However, to assess trends over time, it must be considered that methodological changes in the calculation of prevalences have been necessary and that the reference system has been revised. OBJECTIVE: Are the effects of the methodological changes in weighting factors and reference systems so important that they significantly influence the available prevalence estimates and statements on trends over time? MATERIALS AND METHODS: The data are based on valid measurements of body height and weight from the KiGGS baseline survey (2003-2006, 7531 boys and 7215 girls) and from KiGGS Wave 2 (2014-2017, 1762 boys and 1799 girls). The participants were aged between 3 and 17 years. Prevalences (%, 95% CI) of underweight, overweight and obesity for the KiGGS baseline survey were calculated depending on the reference system and different weighting factors used. RESULTS: The statements on the temporal trend in the prevalence of underweight, overweight, and obesity remain valid even when methodological changes are taken into account. Only among 16- and especially 17-year-old girls, can a noticeable difference due to the altered reference system be noted. DISCUSSION: With regard to the trend examined here, the methodological changes can be neglected, as long as no small subgroups are analysed. However, this conclusion cannot be generalised; the effects of methodological changes must be re-examined for each study question.

[Body mass index among children and adolescents: prevalences and distribution considering underweight and extreme obesity : Results of KiGGS Wave 2 and trends]. / Body-Mass-Index von Kindern und Jugendlichen: Prävalenzen und Verteilung unter Berücksichtigung von Untergewicht und extremer Adipositas : Ergebnisse aus KiGGS Welle 2 und Trends.

BACKGROUND: The current results of the "German Health Interview and Examination Survey for Children and Adolescents" (KiGGS Wave 2, 2014-2017) indicate that the prevalence of overweight and obesity among children and adolescents in Germany has hardly changed during this period. OBJECTIVES: What are the current prevalences for the other categories of the BMI distribution (severe underweight, underweight, and extreme obesity) and what changes have occurred between the KiGGS baseline survey (2003-2006) and KiGGS Wave 2 with regard to the BMI categories and the distribution of BMI values? MATERIALS AND METHODS: KiGGS Wave 2 analyses are based on data from 1762 boys and 1799 girls aged 3 to 17 years with valid measurements of height and weight. The KiGGS baseline survey provides information on 7531 boys and 7215 girls for trend evaluations. RESULTS: For underweight prevalence as well as for the prevalence of extreme obesity no change over time can be observed. The BMI percentiles also show only minor differences between the two survey periods with a marginal shift of the upper BMI percentiles downwards before puberty and a slight increase after puberty. There is no clear shift in the BMI distribution towards lower BMI values. DISCUSSION: There are now many activities at the national, regional, and local level that focus on prevention and intervention to reduce overweight and obesity. The marginal shifts in the upper BMI percentiles in the upper BMI percentiles before puberty observed here suggest that some success may have been achieved in obesity prevention among children in Germany.

An unambiguous definition of pediatric hypotension is still lacking: Gaps between two percentile-based definitions and Pediatric Advanced Life Support/Advanced Trauma Life Support guidelines.

BACKGROUND: Data are lacking to provide cutoffs for hypotension in children based on outcome studies and Pediatric Advanced Life Support (PALS), and Advanced Trauma Life Support (ATLS) definitions are based on normal populations. The goal of this study was to compare different normal population based cutoffs including fifth percentile of systolic blood pressure (P5-SBP) in children and adolescents from the German Health Examination Survey for Children and Adolescents (KiGGS), US population data (Fourth Report), and cutoffs from PALS and ATLS guidelines. METHODS: Fifth percentile of systolic blood pressure according to age, sex, and height was modeled based on standardized resting oscillometric BP measurements (12,199 children aged 3-17 years) from KiGGS 2003-2006. In addition, we applied the age-adjusted pediatric shock index in the KiGGS study. RESULTS: The KiGGS P5-SBP was on average 7 mm Hg higher than Fourth Report P5-SBP (5-10 mm Hg depending on age-sex group). For children aged 3 to 9 years, KIGGS P5-SBP at median height follows the formula 82 mm Hg + age; for age 10 to 17 years, the increase was not linear and is presented in a simplified table. Pediatric Advanced Life Support/ATLS thresholds were between KiGGS and Fourth Report until age of 11 years. The adult threshold of 90 mm Hg was reached by KiGGS P5-SBP median height at 8 years, PALS/ATLS at age of 10 years, and Fourth Report P5-SBP at 12 years. The pediatric shock index, which is supposed to identify severely injured children, was exceeded by 2.3% nonacutely ill KiGGS participants. CONCLUSION: Our study shows that percentile cutoffs vary by reference population. The 90 mm Hg cutoff for adolescents targets only those in the less than 1% of the low SBP range and represents an undertriage compared with P5 at younger ages according to both KiGGS and Fourth Report. Finally, current pediatric shock index cutoffs when applied to a healthy cohort lead to a relevant percentage of false positives. LEVEL OF EVIDENCE: Epidemiologic/prognostic, level III.

Tracking of Blood Pressure in Children and Adolescents in Germany in the Context of Risk Factors for Hypertension.

Blood pressure (BP) tracking from childhood to adulthood has two aspects: the ranking stability relative to others over time and the prediction of future values. This study investigates BP tracking in children and adolescents in Germany in the context of hypertension risk factors. BP was measured and analyzed in 2542 participants of the German Health Examination Survey for Children and Adolescents (t0 2003-2006; 3 to 17-year olds) and of a six year follow-up "Motorik Modul" (t1 2009-2012; 9 to 24-year olds). BP tracking coefficients were calculated from Spearman's rank-order correlations. Predictive values and logistic regression models were used to forecast t1-BP above the hypertension threshold from t0-BP as well as from baseline and follow-up hypertension risk factors. BP tracking was moderate (0.33-0.50 for SBP and 0.19-0.39 for DBP) with no statistically significant differences between sex and age groups. Baseline hypertensive BP was the strongest independent predictor of hypertensive BP at follow-up (OR 4.3 and 3.4 for age groups 3-10 and 11-17 years) after adjusting for sex, BMI trajectories, birthweight, parental hypertension, and age-group dependent-sports/physical activity. However, the positive predictive value of baseline hypertensive BP for hypertensive BP at follow-up in 3- to 10-year olds was only 39% (34% in 11- to 17-year olds) and increased only moderately in the presence of additional risk factors. Our analysis with population-based data from Germany shows that BP in children and adolescents tracks only moderately over six years. BP in childhood is the strongest independent predictor of future BP but its predictive value is limited.

Resting Heart Rate Percentiles and Associated Factors in Children and Adolescents.

OBJECTIVES: To present population-based resting heart rate (RHR) percentiles and associated factors in children and adolescents. STUDY DESIGN: Standardized RHR measurements with an oscillometric device were obtained from 3- to 17-year-olds who participated in the German Health Interview and Examination Survey for Children and Adolescents (n = 11 986). Age- and sex-specific RHR percentiles were derived using flexible age-dependent modeling. Linear regression was used to test associations of RHR and associated factors. RESULTS: RHR decreased with age and mean RHR was on average 3.0 beats per minute (bpm) higher in girls than in boys (P < .01). The 95th RHR-KiGGS-percentile (P95) in boys and girls are up to 10 bpm lower than P95 based on pooled heterogeneous international studies and more similar to percentiles based on population data from NHANES (higher or lower by ≤5 bpm, depending on age). Factors independently associated with RHR in both sexes were age, SBP and height in children aged 3-10 years; and age, systolic blood pressure, and high aerobic fitness in adolescents aged 11-17 years. In girls, we further found an association between RHR and underweight (OR 3.3 and 4.7 for underweight girls aged 3-10 and 11-17, respectively, compared with normal weight girls). Associations between RHR and aerobic fitness, physical activity, and media use were stronger in boys than in girls. CONCLUSION: This study provides population-based RHR percentiles and evidence for sex-dependent associations of cardiovascular risk factors with RHR in children and adolescents, many of which are lifestyle related.

Cytomegalovirus Seroprevalence Among Children and Adolescents in Germany: Data From the German Health Interview and Examination Survey for Children and Adolescents (KiGGS), 2003-2006.

Background. Congenital cytomegalovirus (CMV) infection can cause severe birth defects. The majority of children with congenital CMV are born to CMV-seropositive women; however, transmission from mother to fetus and resulting defects are more likely to occur when mothers experience seroconversion during pregnancy. The objective of this study was to provide a population-based estimate of CMV seropositivity and to identify factors that correlate with the detection of CMV-immunoglobulin (Ig)G antibodies. Methods. Cytomegalovirus-specific IgG antibodies were determined by enzyme-linked immunosorbent assay in 13 876 serum samples from children and adolescents (aged 1-17 years). Cytomegalovirus seroprevalence was correlated with children's age, gender, migration background, country of origin, place of birth, socioeconomic status, breast feeding, daycare attendance, order and number of siblings, and residence in East versus West Germany. Results. Age-adjusted seroprevalence was 27.4% (95% confidence interval, 25.8-29.0). Cytomegalovirus seroprevalence increased with age (21.5% at ages 1-2; 32.0% at ages 14-17). Cytomegalovirus seropositivity was significantly associated with migration background, country of origin and place of birth, and (among migrants only) with low socioeconomic status. Risk factors for CMV acquisition included the birth order of siblings, breastfeeding, early daycare attendance, and living in East Germany. Conclusions. In Germany, CMV seroprevalence increases with age, irrespective of gender. These data highlight risk factors associated with seroprevalence and help to identify a target age for the application of a CMV vaccine.

Changes in diabetes care indicators: findings from German National Health Interview and Examination Surveys 1997-1999 and 2008-2011.

OBJECTIVES: To investigate changes in type 2 diabetes care indicators over time in Germany. METHODS: Adults aged 45-79 years with type 2 diabetes were identified from two national health examination surveys conducted in 1997-1999 (GNHIES98, n=333) and in 2008-2011 (DEGS1, n=526). We examined diabetes care indicators including treatment and preventive targets (glycemic control, blood pressure (BP), total cholesterol (TC), smoking, weight reduction, sports activity), self-management and care process measures (glucose self-monitoring, holding a diabetes passport, annual foot and eye examination; statin use), and the presence of diabetes-specific complications (diabetic nephropathy, retinopathy, neuropathy, diabetic foot, amputations) and comorbid cardiovascular disease (CVD) or chronic kidney disease (CKD). We calculated proportions of persons meeting these care indicators by survey and examined unadjusted and adjusted changes between surveys. RESULTS: Significant improvement (GNHIES98 vs DEGS1) over time was observed for glycated hemoglobin (HbA1c) <7.0% (53 mmol/mol) (32.4% vs 65.4%), BP <130/80 mm Hg (32.0% vs 47.2%), TC <190 mg/dL (13.5% vs 41.9%), statin use (11.7% vs 35.9%), eye (51.1% vs 78.4%) and foot (48.0% vs 61.4%) examination within the past 12 months, diabetes-specific complications (29.7% vs 21.8%), and CVD (44.5% vs 37.1%). Blood glucose self-monitoring significantly increased (37.4% vs 62.8%), while holding a diabetes passport did not change. Current smoking did not change and obesity rose, although sports activity significantly increased over time. Proportions of adults achieving combination goals of HbA1c, BP, TC, and smoking cessation were low in both surveys in spite of significant improvement. CONCLUSIONS: In Germany, the quality of diabetes care improved over time. There is much room for improvement, in particular regarding preventive goals and diabetes self-management.

Updated prevalence rates of overweight and obesity in 11- to 17-year-old adolescents in Germany. Results from the telephone-based KiGGS Wave 1 after correction for bias in self-reports.

BACKGROUND: The nationwide "German Health Interview and Examination Survey for Children and Adolescents" (KiGGS), conducted in 2003-2006, showed an increase in the prevalence rates of overweight and obesity compared to the early 1990s, indicating the need for regularly monitoring. Recently, a follow-up-KiGGS Wave 1 (2009-2012)-was carried out as a telephone-based survey, providing self-reported height and weight. Since self-reports lead to a bias in prevalence rates of weight status, a correction is needed. The aim of the present study is to obtain updated prevalence rates for overweight and obesity for 11- to 17-year olds living in Germany after correction for bias in self-reports. METHODS: In KiGGS Wave 1, self-reported height and weight were collected from 4948 adolescents during a telephone interview. Participants were also asked about their body perception. From a subsample of KiGGS Wave 1 participants, measurements for height and weight were collected in a physical examination. In order to correct prevalence rates derived from self-reports, weight status categories based on self-reported and measured height and weight were used to estimate a correction formula according to an established procedure under consideration of body perception. The correction procedure was applied and corrected rates were estimated. RESULTS: The corrected prevalence of overweight, including obesity, derived from KiGGS Wave 1, showed that the rate has not further increased compared to the KiGGS baseline survey (18.9 % vs. 18.8 % based on the German reference). CONCLUSION: The rates of overweight still remain at a high level. The results of KiGGS Wave 1 emphasise the significance of this health issue and the need for prevention of overweight and obesity in children and adolescents.

Change in the association of body mass index and systolic blood pressure in Germany - national cross-sectional surveys 1998 and 2008-2011.

BACKGROUND: A recent weakening and even decoupling of the association of body mass index (BMI) and systolic blood pressure (SBP) in population data was reported, i. a. for Western Europe. METHODS: The association of BMI and SBP in recent cross-sectional population data from Germany was investigated in participants aged 18-79 years with BMI 17.5-40 kg/m(2) from national health examination surveys 1998 (n = 6,931) and 2008-2011 (n = 6,861) in Germany. The association was analyzed both in the overall samples and in participants without antihypertensive medication. RESULTS: From 1998 to 2008-11, age- and sex-standardized mean SBP decreased from 129.0 (CI 128.2-129.7) to 124.1 (123.5-124.6) mmHg in all participants and from 126.0 (125.4-126.7) to 122.3 (121.7-122.8) mmHg among persons not on antihypertensive medication. The proportion of persons treated with antihypertensives augmented from 19.2 % (17.7-20.8) to 25.3 % (24.0-26.6). Mean BMI remained constant at around 27 kg/m(2) with a slight increase in obesity prevalence. BMI was positively associated with SBP both in 1998 and 2008-11, yet the association tended to level out with increasing BMI suggesting a non-linear association. The strength of the BMI-SBP-association decreased over time in all and untreated men. In women, the association weakened in the overall sample, but remained similarly strong in untreated women. The unadjusted linear regression models were used to estimate the increase in SBP within 5-unit BMI increases. E. g. for men in 1998, SBP was higher by 7.0 mmHg for a BMI increase from 20 to 25 kg/m(2) and by 3.6 mmHg for BMI 30 to 35 kg/m(2). The corresponding values for 2008-11 were 3.8 mmHg and 1.7 mmHg. CONCLUSIONS: The cross-sectional association of BMI and SBP decreased between 1998 and 2008-11 in Germany, however it did not disappear and it is in part explained by improvements in the diagnosis and treatment of high blood pressure.

Development and validation of correction formulas for self-reported height and weight to estimate BMI in adolescents. Results from the KiGGS study.

OBJECTIVE: The use of reported instead of measured height and weight induces a bias in prevalence rates for overweight and obesity. Therefore, correction formulas are necessary. METHODS: Self-reported and measured height and weight were available from the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) baseline study (2003-2006) from 3,468 adolescents aged 11-17 years. With regression analyses, correction formulas for height and weight were developed. Cross-validation was conducted in order to validate and compare the formulas. Corrected BMI was calculated, and corrected prevalence rates were estimated. Sensitivity, specificity, and predictive values for overweight and obesity were calculated. RESULTS: Through the correction procedure, the mean differences between reported and measured height and weight become remarkably smaller and thus the estimated prevalence rates more accurate. The corrected proportions for overweight and obesity are less under-reported, while the corrected proportions for underweight are less over-reported. Sensitivity for overweight and obesity increased after correction. Specificity remained high. CONCLUSION: The validation process showed that the correction formulas are an appropriate tool to correct self-reports on an individual level in order to estimate corrected prevalence rates of overweight and obesity in adolescents for studies which have collected self-reports only.

Association between hemoglobin A1c and all-cause mortality: results of the mortality follow-up of the German National Health Interview and Examination Survey 1998.

OBJECTIVE: This study examined the association of HbA1c-defined glycemic status and continuous HbA1c with all-cause mortality. RESEARCH DESIGN AND METHODS: The study population comprised 6,299 participants (aged 18-79 years) of the German National Health Interview and Examination Survey 1998, who were followed up for mortality for an average of 11.6 years. Glycemic status was defined as known diabetes (self-reported diagnosis or intake of antidiabetic medication) and based on HbA1c levels according to American Diabetes Association diagnostic criteria as undiagnosed diabetes (≥6.5% [≥48 mmol/mol]), prediabetes with very high (6.0-6.4% [42-46 mmol/mol]) or high diabetes risk (5.7-5.9% [39-41 mmol/mol]), and normoglycemia (<5.7% [<39 mmol/mol]). Associations between glycemic status and mortality were examined by Cox regression adjusting for age, sex, education, lifestyle factors, anthropometric measures, and history of chronic diseases (reference: normoglycemia). Spline models were fitted to investigate associations between continuous HbA1c and mortality among participants without known diabetes. RESULTS: Excess mortality risk was observed for participants with known diabetes (hazard ratio 1.41 [95% CI 1.08-1.84]) and undiagnosed diabetes (1.63 [1.23-2.17]) but not for those with high (1.02 [0.80-1.30]) or very high diabetes risk (0.87 [0.67-1.13]). Spline models revealed a U-shaped association, with lowest risk at HbA1c levels 5.4-5.6% (36-38 mmol/mol) and a significantly increased risk at ≤5.0% (≤31 mmol/mol) and ≥6.4% (≥46 mmol/mol). CONCLUSIONS: Unlike known and undiagnosed diabetes, HbA1c levels in the prediabetic range were not associated with an increased mortality risk. The observed U-shaped relationship adds to existing evidence that not only high but also low HbA1c levels might be associated with all-cause mortality.

Classification tree analyses reveal limited potential for early targeted prevention against childhood overweight.

OBJECTIVE: Whether specific combinations of risk factors in very early life might allow identification of high-risk target groups for overweight prevention programs was examined. DESIGN AND METHODS: Data of n = 8981 children from the German KiGGS study were analyzed. Using a classification tree approach, predictive risk factor combinations were assessed for overweight in 3-6, 7-10, and 11-17-year-old children. RESULTS: In preschool children, the subgroup with the highest overweight risk were migrant children with at least one obese parent, with a prevalence of 36.6 (95% confidence interval or CI: 22.9, 50.4)%, compared to an overall prevalence of 10.0 (8.9, 11.2)%. The prevalence of overweight increased from 18.3 (16.8, 19.8)% to 57.9 (46.6, 69.3)% in 7-10-year-old children, if at least one parent was obese and the child had been born large-for-gestational-age. In 11-17-year-olds, the overweight risk increased from 20.1 (18.9, 21.3)% to 63.0 (46.4, 79.7)% in the highest risk group. However, high prevalence ratios were found only in small subgroups, containing <10% of all overweight cases in the respective age group. CONCLUSIONS: Our results indicate only a limited potential for early targeted preventions against overweight in children and adolescents.

Abdominal obesity in German adolescents defined by waist-to-height ratio and its association to elevated blood pressure: the KiGGS study.

OBJECTIVE: The aim of this study was to compare the fixed 0.5 cut-off and the age- and sex-specific 90th percentile (P90) for waist-to-height ratio (WHtR) in German adolescents with respect to the prevalence of abdominal obesity and to compare the screening ability of WHtR and BMI to identify hypertensive blood pressure (BP) values. METHODS: Between 2003 and 2006, the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) was carried out including 3,492 boys and 3,321 girls aged 11-17 years. Abdominal obesity was assessed by two WHtR cut-points (P90; 0.5). Hypertensive BP was defined as BP exceeding age-, sex- and height-specific 95th percentiles or the adult threshold for hypertension (140/90 mm Hg). RESULTS: Agreement between the WHtR cut-offs was very good (Kappa 0.89 for boys; 0.81 for girls), and the prevalence of abdominal obesity was slightly higher using P90 (boys 12.0%; girls 11.3%) compared to 0.5 (boys 10.7%; girls 8.0%). WHtR and BMI-for-age had equivalent ability to discriminate hypertensive BP (ROC-AUC < 0.7; sensitivity of the 0.5 cut-off for detecting hypertensive BP < 30%). CONCLUSION: The fixed 0.5 WHtR cut-off can be used in German adolescents to characterize abdominal obesity. However, WHtR is not suitable as a screening tool for hypertensive BP in adolescents.

Attributable risks for childhood overweight: evidence for limited effectiveness of prevention.

OBJECTIVE: Calculation of attributable risks (ARs) of childhood overweight to estimate effectiveness of prevention strategies. METHODS: We used pooled data of 4 population-based German studies including 34240 children and adolescents aged 3 to 18 years to calculate the impact of familial, social, "early life", and lifestyle factors on overweight. ARs (joint for all determinants as well as partial risks) were calculated. RESULTS: The prevalence of childhood overweight was 13.4%. Successfully tackling all determinants can reduce overweight by 77.7% (ie, from 13.4% to 3.0%; = joint AR) with partial effects of treating parental overweight (42.5%); improving social status (14.3%); reducing media time to <1 hour per day (11.4%); and not smoking during pregnancy, low weight gain during pregnancy, and breastfeeding (together 9.5%), respectively. Improving all preventable risk factors (ie, early life factors and lifestyle) the effect is 9.2%. Media time has the strongest effect. CONCLUSIONS: The determinants identified explained 78% of the prevalence of overweight. Taking into account the partial ARs, the effectiveness of lifestyle interventions to prevent overweight in children is limited. Our data argue in favor of interventions aimed at families and social environments, with a major focus on promoting a lower screen time and computer use in children.

Comparison of BMI derived from parent-reported height and weight with measured values: results from the German KiGGS study.

The use of parent-reported height and weight is a cost-efficient instrument to assess the prevalence of children's weight status in large-scale surveys. This study aimed to examine the accuracy of BMI derived from parent-reported height and weight and to identify potential predictors of the validity of BMI derived from parent-reported data. A subsample of children aged 2-17 years (n = 9,187) was taken from the 2003-2006 cross-sectional German KiGGS study. Parent-reported and measured height and weight were collected and BMI was calculated. Besides descriptive analysis, linear regression models with BMI difference and logistic regression models with weight status misclassification as dependent variables were calculated. Height differences varied by gender and were generally small. Weight and BMI were under-reported in all age groups, the under-reporting getting stronger with increasing age. Overall, the proportion for overweight and obesity based on parental and measured reports differed slightly. In the youngest age group, the proportion of overweight children was overestimated, while it was underestimated for older children and adolescents. Main predictors of the difference between parent reported and measured values were age, gender, weight status and parents' perception of the child's weight. In summary, the exclusive use of uncorrected parental reports for assessment of prevalence rates of weight status is not recommended.

Indicators of overweight and cardiovascular disease risk factors among 11- to 17-year-old boys and girls in Germany.

OBJECTIVE: We analyzed the magnitude of the association between cardiovascular disease (CVD) risk factors and various measures of overweight among adolescents, to determine which indicator of overweight is most relevant for risk assessment. METHODS: 5,546 boys and girls aged 11-17 years participating in the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) were studied. Overweight was assumed when different anthropometric variables exceeded age- and sex-specific 90th percentiles. Blood pressure was measured and blood samples were analyzed for serum total cholesterol, lipoproteins, high-sensitivity C-reactive protein, and glycosylated hemoglobin (HbA1c). RESULTS: In both sexes, overweight was significantly associated with adverse levels of CVD risk factors, except HbA1c. These associations were most pronounced for overweight as defined by waist circumference (WC), waist-to-height ratio (WHtR), or BMI. Between 11% and 37% of the overweight children exceeded the defined cut-offs for individual CVD risk factors, with age- and puberty-adjusted significant odds ratios (95% confidence interval (CI)) in comparison to normal-weight age mates ranging from 1.7 (1.0-3.0) to 6.1 (4.5-8.2). CONCLUSIONS: The findings of this population-based survey suggest that, among adolescents, WC, WHtR, and BMI are easily applicable measures of overweight that appear to be relevant for CVD risk assessment.