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A F Roche

Publications and source records attributed to A F Roche.

At least 37 records · Page 2Linked to original sources
PubMed1993

Obesity in children and adolescents: development of predictive equations and their application to epidemiologic studies.

Epidemiological studies of body fatness cannot be based on laboratory measures. One alternative is to analyze values related to body composition such as skinfold thicknesses, but it is better to apply an equation that accurately predicts a body composition variable. If an equation is to be developed, the choice of the dependent variable affects the selection of the independent variables to be tested for inclusion. The validation group should have a wide distribution of values for the dependent and independent variables. To develop an equation that works well on validation and with other groups, all possible sub-set regression should be applied, multicollinearity examined, and ridge and robust regression used if these are needed. An equation chosen from the literature should have been developed and tested by appropriate methods and it should be validated against data from a sub-group of the study sample.

Adolescent↗
PubMed1993

Serial analysis of plasma lipids and lipoproteins from individuals 9-21 y of age.

Total cholesterol (TC) and low-density- (LDL-C) and high-density-lipoprotein cholesterol (HDL-C) concentrations were recorded annually from 9 to 21 y of age to study tracking and predictive values for adulthood lipid concentrations associated with cardiovascular disease. The tracking coefficients for TC and LDL-C were congruent to 0.7 for 4-, 6-, and 12-y intervals, indicating good predictive value at ages 9-11 y for risk of elevated concentrations at ages 19-21 y. Tracking of HDL-C was less marked but the patterns were similar. The risk ratios for high concentrations at 19-21 y were 3.8 for TC, 2.6 for LDL-C, and 4 for HDL-C for 9-y-olds with values of 5.17 mmol/L for TC, 3.36 mmol/L for LDL-C, and 0.90 mmol/L for HDL-C, relative to 9-y-olds with values of 4.65 mmol/L for TC, 2.84 mmol/L for LDL-C, and 1.29 mmol/L for HDL-C.

Adolescent↗
PubMed1993

Genetic analysis of patterns of growth in infant recumbent length.

A genetic basis to growth and development has been demonstrated in many heritability studies of anthropometrics. Although such measures describe the extent of growth at particular times, they do not fully address the process of growth. We applied a three-parameter curve-fitting function to serial measures of recumbent length from 569 infants (birth to 2 years of age) in 188 families enrolled in the Fels Longitudinal Study. This yielded three growth pattern parameters that represented estimated recumbent length at birth (parameter 1), rate of growth (parameter 2), and intrinsic rate of change in growth (parameter 3). The growth pattern parameter estimates for each individual were examined in a series of genetic analyses using a maximum-likelihood method for pedigree data. Significant heritabilities were found for all three growth pattern parameters: parameter 1, h2 = 0.83 +/- 0.12; parameter 2, h2 = 0.67 +/- 0.18; and parameter 3, h2 = 0.78 +/- 0.17. In addition, genotype by sex interaction was indicated for growth pattern parameters 2 and 3, suggesting that the genes influencing rate of growth and intrinsic rate of change in growth are themselves influenced by the sex of the individual.

Anthropometry↗
PubMed1993

Reliability of B-mode ultrasonic measurements of subcutaneous adipose tissue and intra-abdominal depth: comparisons with skinfold thicknesses.

Adipose tissue deposits, particularly intra-abdominal adipose tissue, are associated with health risks such as diabetes mellitus and cardiovascular disease. Anthropometric techniques currently in use can measure subcutaneous adipose tissue (SAT) with skinfold calipers, but are limited to certain sites and cannot measure intra-abdominal adipose tissue (IAAT). Radiography, computerized tomography (CT) and magnetic resonance imaging (MRI) have been used, but they are expensive and some involve exposure to radiation. This study, which investigated the utility of B-mode ultrasound for measuring adipose tissue, found that ultrasonic measurements of SAT were as reliable as skinfold caliper measurements. Intra-observer and inter-observer coefficients of reliability for five of six ultrasonic measurements of SAT ranged from 91-98%, in comparison with coefficients of reliability ranging from 93-98% for three skinfold measurements. Coefficients of reliability for ultrasonic measurements of SAT at the paraspinal site were below 90%. Ultrasonic measurements of intra-abdominal depth (IAD), an index of IAAT, yielded an inter-observer coefficient of reliability of 64%. Ultrasound is recommended for measurement of subcutaneous adipose tissue but not for measurement of IAD.

Abdomen↗
PubMed1992

Serial changes in blood pressure from adolescence into adulthood.

High blood pressure is an established risk factor for cardiovascular disease outcomes in adulthood. Furthermore, numerous longitudinal studies of blood pressure in childhood with length of follow-up from 1 to 17 years indicate that blood pressure levels track over the short term. This study addresses the question of the predictive value of childhood blood pressure readings for adult levels, using repeated blood pressure determinations from a sample of 501 participants in the Fels Longitudinal Study, an ongoing cohort study in southwestern Ohio that began in 1929. A damped autoregressive model indicated tracking correlations from 0.39 (4-year intervals) to 0.24 (20 years) for systolic pressure and 0.37 (4 years) to 0.20 (20 years) for diastolic pressure. These results indicate that tracking of blood pressure persists from age 13 years to age 40 years, which translates into moderate levels of relative risk for adult hypertension (diastolic pressure above 90 mmHg) for adolescents with high normal blood pressure. The estimated relative risks of hypertension at age 35 for white 15-year-olds with a true mean diastolic pressure of 80 mmHg were 1.9 for males and 2.6 for females, relative to 15-year-olds with a true diastolic pressure of 60 mmHg.

Adolescent↗
PubMed1992

Bioelectrical impedance estimation of fat-free body mass in children and youth: a cross-validation study.

The purposes of this study were to develop and cross-validate the "best" prediction equations for estimating fat-free body mass (FFB) from bioelectrical impedance in children and youth. Predictor variables included height2/resistance (RI) and RI with anthropometric data. FFB was determined from body density (underwater weighing) and body water (deuterium dilution) (FFB-DW) and from age-corrected density equations, which account for variations in FFB water and bone content. Prediction equations were developed using multiple regression analyses in the validation sample (n = 94) and cross-validated in three other samples (n = 131). R2 and standard error of the estimate (SEE) values ranged from 0.80 to 0.95 and 1.3 to 3.7 kg, respectively. The four samples were then combined to develop a recommended equation for estimating FFB from three regression models. R2 and SEE values and coefficients of variation from these regression equations ranged from 0.91 to 0.95, 2.1 to 2.9 kg, and 5.1 to 7.0%, respectively. As a result of all cross-validation analyses, we recommend the equation FFB-DW = 0.61 RI + 0.25 body weight + 1.31, with a SEE of 2.1 kg and adjusted R2 of 0.95. This study demonstrated that RI with body weight can predict FFB with good accuracy in Whites 10-19 yr old.

Adipose Tissue↗
PubMed1991

Measures of body composition. Their relationship to blood pressure and use in epidemiologic research.

The association between "overweight" and increased risk of high blood pressure has long been recognized. The quantification of overweight into various aspects of body composition and the relationships of these aspects to blood pressure remain important areas of current research. The manner in which adipose tissue is distributed over the body is proving to be another important risk factor. Methodologies for assessing body composition include a variety of approaches commonly used in epidemiologic studies, ranging from simple indices (e.g., body mass index) to estimation of total body fat mass from equations based on skinfolds and other anthropometry, to newer approaches incorporating bioelectric impedance. Refined laboratory methods for assessing body composition are important in the study of small groups and in the development of predictive equations. These refined methods include the traditional approaches of hydrostatic weighing and K40 determinations, as well as newer improvements on these techniques incorporating estimates of bone mineral content and total body water. Other new sophisticated methodologies include dual-energy x-ray absorptiometry and nuclear magnetic resonance imaging. The approach to assessing body composition may vary among age groups; methodologies applicable to children may not work for the elderly.

Blood Pressure↗
PubMed1991

Reference data on gains in weight and length during the first two years of life.

Serial data from studies of infants at the University of Iowa and from the Fels Longitudinal Study were used to develop sex-specific percentiles for increments in weight and recumbent length for selected intervals during the first 24 months of life. Weight increments are presented for 1-month intervals from birth to 6 months, 2-month intervals from birth to 12 months, and 3-month intervals from birth to 24 months. Length increments are presented for 2-month intervals from birth to 6 months, and for 3-month intervals from birth to 24 months of age. Weights and lengths at the target ages were obtained for the Iowa data by simple interpolation, and for the Fels data by fitting families of three-parameter mathematical functions to the serial data from ages 1 to 24 months. The tabular presentations are based on the Iowa data from birth to 3 months of age, on the combined Iowa and Fels data from 3 to 6 months of age, and on the Fels data from 6 to 24 months of age. We believe that these reference data will be useful in screening for deviations from normal growth and may aid in early detection of failure to thrive or excessive weight gain during early life.

Age Factors↗
PubMed1991

Patterns of change in weight/stature2 from 2 to 18 years: findings from long-term serial data for children in the Fels longitudinal growth study.

Serial weight/stature2 (W/S2) data recorded semi-annually from 2 to 18 years in the Fels longitudinal study were analyzed to establish an approach for the investigation of long-term serial changes in body fatness during childhood and adolescence in individuals. To describe patterns of change in body fatness during childhood and adolescence, a family of mathematical models was fitted to individual serial W/S2 data recorded from 250 boys and 246 girls. The selected models fitted the W/S2 data well as judged by the root mean square errors. Based on the fitted models, variables representing patterns of change in an individual were derived. These included estimated value of W/S2 at 2 years of age (W/S(2)2yr), minimum value of W/S2 (W/S2min), age at minimum value of W/S2 (Amin), maximum velocity of W/S (Vmax), age at maximum velocity of W/S2 (AVmax), maximum value of W/S2 (W/S2max), and age at maximum value of W/S2 (Amax). There were highly significant correlations between observed W/S2 at 18 years and all the derived variables except AVmax indicating, for example, that in both sexes about 25 percent of the variation in W/S2 at 18 years could be explained by when Amin occurs or by the value of W/S2min. The negative correlations (r = -0.5) between Amin and W/S2 at 18 years suggested that the earlier children reach their nadir in W/S2, the earlier they began to increase in adiposity and the fatter they were at 18 years. Likewise, the positive correlations (r approximately 0.3 and 0.5, respectively) between the W/S(2)2yr or W/S2min and W/S2 at 18 years indicated that increased childhood adiposity may lead to increased adult adiposity.

Adipose Tissue↗
PubMed1990

Differences between the hand-wrist and the knee in assigned skeletal ages.

Skeletal ages were assessed for 4,902 pairs of hand-wrist and knee radiographs of children aged 2-17 years. The FELS method was used to assess the hand-wrist, and the RWT method was used to assess the knee. These methods have the same conceptual and statistical basis. The mean absolute differences, within age- and sex-specific groups, ranged from 0.34 to 0.87 years. The SD of the differences ranged from 0.31 to 0.68 years and, like the means, tended to increase with age until about 8-11 years. The means and SD were generally larger for the boys than for the girls, except after 14 years. Within age- and sex-specific groups, the maximum absolute differences were from 1.45 to 2.99 years. These maximum differences changed irregularly with age but tended to increase until 11 years in the boys and 9 years in the girls. These large absolute differences between the skeletal ages of the hand-wrist and the knee cannot be explained completely by the effects of observer errors. The means of the relative (signed) differences between the skeletal ages of the hand-wrist and the knee were all close to zero, but there was a wide range within age- and sex-specific groups. These skeletal ages of the hand-wrist and the knee are not interchangeable. The 95th percentiles of the absolute differences show that, in at least 5% of children, the choice of the area for skeletal age assessment will markedly influence the evaluation of individuals. They also demonstrate that descriptions of populations based on distributions of skeletal ages from one part of the skeleton may be misleading.

Adolescent↗