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ARS Home » Plains Area » Houston, Texas » Children's Nutrition Research Center » Research » Publications at this Location » Publication #116434
Title: CORPULENCE OF YOUNG HEMATOLOGICAL PATIENTS: CHARACTERIZATION WITH BODY MASSINDEX OR BODY COMPOSITION

Author
item BRAILLON, PIERRE - UNIV CLAUDE BERNARD
item LAPILLONNE, ALEXANDRE - BAYLOR COLLEGE MED
item CHATELAIN, PIERRE - UNIV CLAUDE BERNARD
item SOUILLET, GERARD - UNIV CLAUDE BERNARD

Submitted to: Journal of Pediatrics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/12/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: We compared the results of measurements of fat mass using dual-energy X-ray absorptiometry (DXA) to those made by the traditional body mass index (BMI) method to see which were optimal choices for accuracy during the long-term treatment of children with blood diseases. The BMI, a ratio that uses a patient's weight and height, is frequently used by doctors because it is an neasy method of assessing whether a person has a weight that is considered appropriate for his/her height. It is important to determine if a person is overweight or obese, and if so, to what extent, because obesity increases the risk for many health problems such as heart disease and diabetes. Such information is very important in treating patients entering long-term treatment for serious blood diseases. Over time, these patients' weight can fluctuate, especially that of growing children, and the BMI value may be too imprecise. Also, treatments for blood diseases often include drugs that tcan affect growth and metabolism. A basic problem with using BMI as an index is that a child could have a high relative BMI but no excess fat. In order to address this issue, we compared BMI to DXA values obtained in a population of 83 young Caucasian patients, 4 to 23 years of age, who were treated for severe blood diseases and had had a bone marrow transplant. We found the BMI data did not work for these patients. They were misclassified as normal or thin by BMI assessment. Many of them had lower than normal BMI values, but their DXA readings indicated their ratio of fat to lean mass was higher than normal. A total of one-third of the patients were mis- classified by BMI. We conclude that BMI cannot precisely estimate fatness and the results should be interpreted with caution, especially in pediatric patients under long-term care.

Technical Abstract: The body mass index (BMI) is widely used to evaluate subjects as normal, under- or overweight. Follow-up evaluation of the body composition of patients involved in long-term clinical treatment is clearly as important as the assessment of normal weight, overweight or obesity in a healthy subject but none of the data published demonstrate that BMI is a useful index for such patients. To address this issue, we determined the BMI values of a group of young patients with severe hematological disease and compared them with the patients' body composition values, as assessed by dual energy X-ray absorptiometry (DXA). Methods: 83 patients (42 females, 41 males) aged 4.1 y to 23.1 y were studied. Among them, 21 females (50.0%), and 31 males (75.6%) had a body mass index (BMI) value lower than normal. The fat (F) and lean (L) masses measured by DXA (Norland XR 36 system) were used to calculate the F/L values, which were compared with the enormal mean reference values. Results: A total of 15 (71.4%) of the female and 12 (38.7%) of the male patients with a below-normal BMI had DXA- measured F/L ratio values that would be considered high (+52%, or42% higher than the normal value in females and males, respectively). A total of 27 patients (32.5% of the population) were misclassified when the BMI was used alone. Conclusion: BMI, a commonly used index, cannot precisely estimate obesity. It should be interpreted with caution, especially in young patients under treatment. Multicompartment estimates of body composition, such as those obtained by DXA, are recommended in order to calculate the ratio of fat and lean, a parameter which appears to be the best approach for precise follow-up of body corpulence.