Human Growth: Assessment and Interpretation

Human Growth: Assessment and Interpretation Many researchers and professionals need to be able to measure, assess, and interpret human growth between birth and adulthood. However, much of the methodology is scattered in diverse literature. Human Growth: Assessment and Interpretation provides a complete reference to the field for all those who measure and assess child growth. It emphasizes the interpretation of growth data taking into account the adjusted effects of influences such as genes, hormones, and substance abuse during pregnancy, gives descriptions of normal and abnormal growth patterns, and of variant growth patterns such as failure-to-thrive and catch-up growth. Including methods to measure size and maturity, the judgement and interpretation of recorded data, evaluations of influences on growth, and the significance of abnormal growth, it will be an essential source of information for pediatricians, human biologists, health workers, nutritionists, epidemiologists, and others who are responsible for the health and welfare of children.          is Fels Professor Emeritus of Community Health and of Pediatrics at Wright State University, Dayton, Ohio. His research has focused on child growth and maturation, body composition, and risk factors for disease, and he has written or edited 60 books and monographs in these fields.        .    is Professor of Community Health at Wright State University, Dayton, Ohio. Trained initially in biostatistics, her expertise is in the development of longitudinal statistical models for analysis of data related to growth, overweight, and obesity, and risk factors for cardiovascular disease.

Human Growth: Assessment and Interpretation Alex F. Roche Wright State University and

Shumei S. Sun (formerly Guo) Wright State University

CAMBRIDGE UNIVERSITY PRESS Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 2RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521782456 © Alex Roche and Shumei Sun 2003 This book is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published 2003 This digitally printed first paperback version 2005 A catalogue record for this publication is available from the British Library Library of Congress Cataloguing in Publication data Roche, Alex F., 1921– Human Growth: Assessment and Interpretation / by Alex F. Roche and Shumei Sun. p. cm. Includes bibliographical references and index. ISBN 0 521 78245 7 (hardback) 1. Children – Growth. 2. Child development. I. Sun, Shumei, 1954– RJ131 .R5915 2003 612.6´54–dc21 2002073462 ISBN-13 978-0-521-78245-6 hardback ISBN-10 0-521-78245-7 hardback ISBN-13 978-0-521-01773-2 paperback ISBN-10 0-521-01773-4 paperback

II. Title.

To Eileen Mater Familiae

Contents

Preface List of abbreviations 1 Measurement and assessment Measurement of weight, size, and total body composition The assessment of maturity Growth reference data for general populations Changes in percentile levels with age Other important measures Total body composition Percentages of values at older ages Multiple births Low birth weight infants Disease-specific growth charts Maturity reference data 2 Patterns of change in size and body composition Mathematical models for describing growth patterns Growth and body composition during infancy Growth and body composition after infancy Tracking Decanalization Failure-to-thrive Catch-up growth Prediction of adult stature Target stature

page ix xii 1 1 9 17 46 47 49 50 54 56 61 71

75 75 80 92 99 106 106 108 109 110

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3 Determinants of growth Genetic influences Family influences Substance abuse during pregnancy Breast-feeding Hormonal influences Ethnic influences Nutritional influences High altitude Maturity

111 111 115 130 141 145 160 163 165 167

4 Secular changes in growth and maturity Changes in size Changes in maturity Recent slowing of secular changes Determinants of secular changes Secular changes and long-term serial growth studies

172 173 182 183 183

5 Significance of human growth Early growth and later growth Maturity Growth and disease Adult stature Assessment of growth Assessment of nutritional status Growth screening

188 188 190 191 195 195 200 201

References Index

205 304

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Preface

the sizes of differences between groups and the strengths of correlations. These data are not so numerous that they occlude the general descriptions and conclusions that are presented. The text has five parts. Chapter 1 describes the equipment needed to make growth measurements and the procedures to be applied. The criteria for growth chart excellence are given and selected growth charts are described. About 50 years ago, all growth charts were for general populations while today many growth charts are for specific groups such as low birth weight infants and untreated children with particular diseases. The shapes of the percentile levels on these charts are noted and their relevance to growth assessment is explained. Methods for the assessment of maturity are given and sources of reference data for growth and maturational status are provided. Chapter 2 reviews patterns of growth for individuals including irregularities of growth during infancy, prepubertal, and pubescent spurts, tracking, and variations from normal growth patterns, such as decanalization, failure-to-thrive, and catchup growth. This Chapter ends with a consideration of the prediction of adult stature and the utility of target stature. Chapter 3 reviews the adjusted effects on growth of genetic and family influences, substance abuse during pregnancy, breast-feeding, hormones, ethnic and nutritional influences, high altitude, and maturity. Knowledge of the effects of these influences is of fundamental importance to the interpretation of growth data. In Chapter 4 attention is given to secular changes in growth and maturity with reference to the influences responsible, and the effects of secular changes on the assessment and interpretation of child growth. Knowledge of these changes within countries is needed to assist

This book collates information from many sources that is necessary for the assessment and interpretation of growth data recorded in clinics or research studies. The large writing task will be justified if the book proves beneficial to professionals who measure the growth of infants and children. These professionals include pediatricians, family practice physicians, dieticians, other health workers, epidemiologists, and human biologists. Part of the material presented may be unfamiliar to some readers, but all the topics covered are relevant to the accurate assessment and interpretation of human growth and maturation, which are central to pediatric practice and public health policies relating to children. The literature review is restricted to reports from developed countries, but there should not be a corresponding restriction of the readership. Those working in lesser-developed countries, who may have limited access to the literature, will gain from a more complete knowledge of what is currently known and the analytic methods that have been applied. The text is appropriate for practicing professionals, graduate students, and senior undergraduates, but is not intended for the casual reader. One impetus to writing this book was the difficulty of collating findings from a multitude of relevant published reports that are scattered in many journals and monographs. With a few exceptions, no more than four recent references are given for any particular statement, which should be sufficient to help the reader evaluate the evidence. Additional references would have broken up the text further, making it difficult to read. Those who wish to review more primary sources should consult electronic databases or the bibliographies in the reports cited. The reader is provided with a considerable amount of numerical data to assist judgements of ix

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Preface

the selection of appropriate reference data. Chapter 5 describes the significance of child growth and maturity in relation to future size, function, and disease. The place of anthropometry in the assessment of nutritional status and the possible justification of screening programs based on measures of growth are evaluated. Growth assessment depends on accurate measurements and the use of growth charts. The accurate assessment and interpretation of the growth status and maturity of a child is important because unusual status values may be associated with current pathological conditions. Additionally, they may be risk factors for chronic diseases. For example, overweight in childhood increases the risk of hypertension, non-insulin-dependent diabetes mellitus and other chronic diseases in adulthood. Growth charts are used primarily by health care professionals in clinical settings and by research workers in epidemiological and clinical studies. They assist judgements of the normality of growth status and help screen for current disease and the presence of risk factors for future disease. These charts present sex-specific, smoothed percentile levels for selected variables or the mean and selected standard deviation levels (Z scores). Typically growth charts display reference levels for weight from birth to 18 or 20 years, length, weight-for-length, and head circumference from birth to 36 months, and stature and body mass index (BMI) from 2 to 18 or 20 years. The measured values for these variables should be plotted on charts and recorded in a tabular format. Comparisons between the plotted points and the percentile or Z score levels on the charts show the approximate level for the child or children compared with the reference population. After the recorded data for a child or a group of children have been compared with the reference percentiles on growth charts, the findings must be interpreted. Accurate interpretation depends on knowledge of growth patterns in relation to age and maturity and the effects of influences that affect the rates of growth and maturation. For such interpretation, any earlier data should be considered so that growth progress can be evaluated. It

may be desirable to schedule another examination to evaluate future growth progress. The interval to the next examination will be determined by the age of the child and, if increments are to be evaluated, by the length of the intervals in the incremental reference data that will be used. This text concentrates on the literature of the past 40 years relating to growth, maturation, and body composition. During this time there has been important progress in the development of statistical methods for the analysis of cross-sectional and serial data, the assessment of skeletal age, and the prediction of adult stature. Furthermore, new procedures have increased our knowledge and understanding of body composition. Much remains to be done. New non-invasive procedures may allow improved studies of prenatal growth and changes in organ size that may relate size to function after adjusting for confounding variables. Our understanding of the construct “socioeconomic status” may improve and better study designs in which reported data are replaced by measured data may provide more accurate estimates of the independent effects of specific influences on growth and maturation. The latter will require the measurement of an enlarged set of confounding variables, including specific genes and selected hormones, to remove the effects of all influences other than the one under study. Most of these advances will require lengthy multi-disciplinary collaboration at all stages of the studies, including the development and choice of apparatus, construction of hypotheses, data collection, and data analysis. Genuine complete collaboration is needed, particularly in emerging topic areas, and it must be based on deep interest in particular research areas and mutual respect among research workers. If this can be achieved, significant increases in our understanding of growth and maturation are likely. We wish to express our gratitude to Donna Menelle and Marianne King for their accurate and professional secretarial support through many drafts. We are grateful to the participants in the Fels Longitudinal Study. Since 1929, they have provided the data that allow us to address topics of great interest concerning child growth and

Preface

maturation. We wish to acknowledge the help given by Howard Kulin, Peter Lee, and Bradford Towne, who reviewed sections of typescript; they are, of course, not responsible for any remaining errors. We have been assisted in the development of our approaches to the study of growth and maturation by many consultants and colleagues particularly Laurel Beckett, Cameron Chumlea, Robert Kuczmarski, Roger Siervogel, David Thissen, and Howard Wainer. Considerable support was

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provided by the National Center for Health Statistics and the National Institute of Child Health and Human Development. We are grateful to Dr. Tracey Sanderson and Dr. Katrina Halliday of the Cambridge University Press who guided the manuscript through all stages of the publication process in a charming and effective manner. Alex F. Roche Shumei S. Sun

Abbreviations

AGA BMC BMD BMI BP CTRH DHEA DHEA-S ELBW FFM FTT GAA GHBP GHRH GnRH IDDM IGF-1 IGF-1 BP IHDP LBW

LGA LMP

Appropriate-(weight)-for-gestational age Bone mineral content (g) Bone mineral density (g per cm2 ) Body mass index Bayley–Pinneau method of stature prediction Corticotropin-releasing hormone Dehydroepiandrosterone Dehydroepiandrosterone sulfate Extremely low birth weight (