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Is failure to thrive a greater concern than obesity?
EDITORIALS
THE JOURNAL OF PEDIATRICS JULY 2002
Is failure to thrive a greater concern than obesity? In the article by Miller et al1 in this issue of The Journal, the anthropometric data collected from patients referred to their failure to thrive (FTT), and obesity clinics suggest that children are referred for lesser degrees of underweight than overweight. The authors believe that these referral patterns reflect a more aggressive approach to
FTT than obesity. Before we can consider the validity of this assertion, similar criteria must be used to compare the underweight and overweight children. To assess the severity of FTT, the authors used weight-for-height criteria derived from Waterlow.2 These criteria are based on percentages of the median
See related article, p 121. Reprint requests: William H. Dietz, MD, PhD, Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, Mailstop K-24, Atlanta, GA 30341.
J Pediatr 2002;141:6-7. Copyright © 2002, Mosby, Inc. All rights reserved. 0022-3476/2002/$35.00 + 0 9/18/125852 doi:10.1067/mpd.2002.125852
6
weight for height: mild underweight is 80% to 90% of expected weight, moderate underweight is 70% to 80% of expected, and severe underweight is <70% of expected weight for height. Categories of obesity were based on the same anthropometric criterion, using the categories of 130% to 150% for
mild overweight, 150% to 170% for moderate overweight, and >170% for severe overweight. The best basis for comparison would have been Z scores, or SD units, which express deviations FTT
Failure to thrive
from the median in terms of numbers of SDs. The Z scores at the time of referral are quite different for underweight and overweight children (Table). To generate the data in our table, we calculated the weight that corresponded to the midpoint of the interval between mild and moderate underweight or mild and moderate overweight as defined by the criteria by either Waterlow or Miller et al, and then calculated the cor-
EDITORIALS
THE JOURNAL OF PEDIATRICS
VOLUME 141, NUMBER 1 responding weight-for-height Z score based on the Centers for Disease Control and Prevention growth charts.3 The mild and moderate overweight categories are 2 SD units greater than the corresponding mild and moderate underweight categories. These data strengthen the case made by Miller et al. Although fewer referrals were in the mild overweight category than in the mild underweight category (22% vs 60%), the degree of overweight was on average more than 2 absolute SD units greater than the group referred for evaluation of FTT. Our calculations underscore the conclusion of Miller et al1 that underweight children are referred at an earlier stage than children who are overweight. These results are not surprising, although no effort has been made to examine this problem. Starvation has been with us for millenia, whereas widespread obesity is a recent arrival. Furthermore, we are familiar with the risks of starvation, whereas a clear appreciation of the risks of obesity is still evolving. Starvation may be perceived as a more acute process, whereas obesity is a chronic disease. These characteristics likely contribute to the anxiety of health care providers trying to decide when a child should be referred for treatment. The article by Miller et al reminds us again that obesity now causes a greater burden of disease, both in terms of prevalence and morbidity. To examine changes in the prevalence of underweight and overweight among young children, we estimated the prevalence of underweight (weight for height ≤5th percentile) and overweight (weight for height ≥95th percentile) in 24- to 71-month-old children measured in the National Health and Nutrition Examination surveys conducted be-
Table. Z score equivalents for weights identified by the mid-point of cutpoints used by Waterlow2 and Miller et al1 to define underweight and overweight
Waterlow criteria Cut point 85% 75%
Z score –1.62 –3.45
tween 1971 and 1994. During this period, the prevalence of underweight fell from 5.5% to 4.1%, and the prevalence of overweight increased from 3.9% to 5.2%. Presuming that national surveys may not adequately assess vulnerable populations, several years ago we examined the prevalence of underweight in at-risk populations such as homeless children or children in Head Start programs. These studies also showed that the prevalence of underweight children was lower than expected, whereas the prevalence of overweight children was greater than expected.4 Furthermore, 60% of overweight 5- to 10-year-old children have at least one additional cardiovascular disease risk factor, and more than 25% have two or more.5 The report that more than 25% of severely overweight children and adolescents have impaired glucose tolerance emphasizes the urgency to develop effective prevention and therapeutic strategies for use in primary and specialty care clinics.6 Although the prevailing notion has been that starvation poses more of a risk for sudden death than obesity, that may no longer be the case. Because the distribution of weight in the United States is shifting to the right, the prevalence of underweight is decreasing at the same time that the prevalence of overweight is increasing. The morbidity of obesity among children and adolescents appears to be increasing synchronously. Although more referrals of less over-
Miller obesity criteria Cut point 140% 160%
Z score +3.98 +5.11
weight children would likely overwhelm any clinic devoted to their care, interventions at an earlier stage in the evolution of overweight will likely be more successful than interventions when obesity is severe. William H. Dietz, MD, PhD Zuguo Mei, MD, MPH Division of Nutrition and Physical Activity Centers for Disease Control and Prevention Atlanta, GA 30341
REFERENCES 1. Miller LA, Grunwald GK, Johnson SL, Krebs NF. Disease severity at time of referral for pediatric failure to thrive and obesity: time for a paradigm shift? J Pediatr 2002;140:121-4. 2. Waterlow JC. Classification and definition of protein-calorie malnutrition. BMJ 1972;3:566-9. 3. Kuczmarski RJ, Ogden CL, GrummerStrawn LM, Flegal KM, Guo SS, Wei R, et al. CDC growth charts—United States. Adv Data 2000;213:1-27. 4. Dietz WH. Undernutrition of children in Massachusetts. J Nutr 1990;948-54. 5. Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study. Pediatrics 1999;103:1175-82. 6. Sinha R, Fisch G, Teague B, Tamborlane WV, Banyas B, Allen K, et al. Prevalence of impaired glucose tolerance among children and adolescents with marked obesity. N Engl J Med 2002;346:802-10.
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THE JOURNAL OF PEDIATRICS JULY 2002
Is failure to thrive a greater concern than obesity? In the article by Miller et al1 in this issue of The Journal, the anthropometric data collected from patients referred to their failure to thrive (FTT), and obesity clinics suggest that children are referred for lesser degrees of underweight than overweight. The authors believe that these referral patterns reflect a more aggressive approach to
FTT than obesity. Before we can consider the validity of this assertion, similar criteria must be used to compare the underweight and overweight children. To assess the severity of FTT, the authors used weight-for-height criteria derived from Waterlow.2 These criteria are based on percentages of the median
See related article, p 121. Reprint requests: William H. Dietz, MD, PhD, Division of Nutrition and Physical Activity, Centers for Disease Control and Prevention, 4770 Buford Hwy NE, Mailstop K-24, Atlanta, GA 30341.
J Pediatr 2002;141:6-7. Copyright © 2002, Mosby, Inc. All rights reserved. 0022-3476/2002/$35.00 + 0 9/18/125852 doi:10.1067/mpd.2002.125852
6
weight for height: mild underweight is 80% to 90% of expected weight, moderate underweight is 70% to 80% of expected, and severe underweight is <70% of expected weight for height. Categories of obesity were based on the same anthropometric criterion, using the categories of 130% to 150% for
mild overweight, 150% to 170% for moderate overweight, and >170% for severe overweight. The best basis for comparison would have been Z scores, or SD units, which express deviations FTT
Failure to thrive
from the median in terms of numbers of SDs. The Z scores at the time of referral are quite different for underweight and overweight children (Table). To generate the data in our table, we calculated the weight that corresponded to the midpoint of the interval between mild and moderate underweight or mild and moderate overweight as defined by the criteria by either Waterlow or Miller et al, and then calculated the cor-
EDITORIALS
THE JOURNAL OF PEDIATRICS
VOLUME 141, NUMBER 1 responding weight-for-height Z score based on the Centers for Disease Control and Prevention growth charts.3 The mild and moderate overweight categories are 2 SD units greater than the corresponding mild and moderate underweight categories. These data strengthen the case made by Miller et al. Although fewer referrals were in the mild overweight category than in the mild underweight category (22% vs 60%), the degree of overweight was on average more than 2 absolute SD units greater than the group referred for evaluation of FTT. Our calculations underscore the conclusion of Miller et al1 that underweight children are referred at an earlier stage than children who are overweight. These results are not surprising, although no effort has been made to examine this problem. Starvation has been with us for millenia, whereas widespread obesity is a recent arrival. Furthermore, we are familiar with the risks of starvation, whereas a clear appreciation of the risks of obesity is still evolving. Starvation may be perceived as a more acute process, whereas obesity is a chronic disease. These characteristics likely contribute to the anxiety of health care providers trying to decide when a child should be referred for treatment. The article by Miller et al reminds us again that obesity now causes a greater burden of disease, both in terms of prevalence and morbidity. To examine changes in the prevalence of underweight and overweight among young children, we estimated the prevalence of underweight (weight for height ≤5th percentile) and overweight (weight for height ≥95th percentile) in 24- to 71-month-old children measured in the National Health and Nutrition Examination surveys conducted be-
Table. Z score equivalents for weights identified by the mid-point of cutpoints used by Waterlow2 and Miller et al1 to define underweight and overweight
Waterlow criteria Cut point 85% 75%
Z score –1.62 –3.45
tween 1971 and 1994. During this period, the prevalence of underweight fell from 5.5% to 4.1%, and the prevalence of overweight increased from 3.9% to 5.2%. Presuming that national surveys may not adequately assess vulnerable populations, several years ago we examined the prevalence of underweight in at-risk populations such as homeless children or children in Head Start programs. These studies also showed that the prevalence of underweight children was lower than expected, whereas the prevalence of overweight children was greater than expected.4 Furthermore, 60% of overweight 5- to 10-year-old children have at least one additional cardiovascular disease risk factor, and more than 25% have two or more.5 The report that more than 25% of severely overweight children and adolescents have impaired glucose tolerance emphasizes the urgency to develop effective prevention and therapeutic strategies for use in primary and specialty care clinics.6 Although the prevailing notion has been that starvation poses more of a risk for sudden death than obesity, that may no longer be the case. Because the distribution of weight in the United States is shifting to the right, the prevalence of underweight is decreasing at the same time that the prevalence of overweight is increasing. The morbidity of obesity among children and adolescents appears to be increasing synchronously. Although more referrals of less over-
Miller obesity criteria Cut point 140% 160%
Z score +3.98 +5.11
weight children would likely overwhelm any clinic devoted to their care, interventions at an earlier stage in the evolution of overweight will likely be more successful than interventions when obesity is severe. William H. Dietz, MD, PhD Zuguo Mei, MD, MPH Division of Nutrition and Physical Activity Centers for Disease Control and Prevention Atlanta, GA 30341
REFERENCES 1. Miller LA, Grunwald GK, Johnson SL, Krebs NF. Disease severity at time of referral for pediatric failure to thrive and obesity: time for a paradigm shift? J Pediatr 2002;140:121-4. 2. Waterlow JC. Classification and definition of protein-calorie malnutrition. BMJ 1972;3:566-9. 3. Kuczmarski RJ, Ogden CL, GrummerStrawn LM, Flegal KM, Guo SS, Wei R, et al. CDC growth charts—United States. Adv Data 2000;213:1-27. 4. Dietz WH. Undernutrition of children in Massachusetts. J Nutr 1990;948-54. 5. Freedman DS, Dietz WH, Srinivasan SR, Berenson GS. The relation of overweight to cardiovascular risk factors among children and adolescents: the Bogalusa Heart Study. Pediatrics 1999;103:1175-82. 6. Sinha R, Fisch G, Teague B, Tamborlane WV, Banyas B, Allen K, et al. Prevalence of impaired glucose tolerance among children and adolescents with marked obesity. N Engl J Med 2002;346:802-10.
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