William A. Rowe

Limits of body mass index to detect obesity and predict body composition

Body mass index (BMI) is commonly used to identify obesity. In this study, we determined how accurately BMI could determine body composition and identify obese from non-obese individuals. Fat-free mass and body fat were determined with bioelectrical impedance. Adiposity was calculated as body fat per body mass and as body fat divided by body height (m2). Obesity was defined as a BMI of at least 30 kg/m2 or an amount of body fat of at least 25% of total body mass for men and at least 30% for women. Obesity as defined by percentage of body fat was always present with a BMI of at least 30 kg/m2. However, 30% of men and 46% of women with a BMI below 30 kg/m2 had obesity levels of body fat. The greatest variability in the prediction of percentage of body fat and body fat divided by height (m2) from regression equations using BMI was at a BMI below 30 kg/m2. In conclusion, using impedance-derived body-fat mass as the criterion, people with BMI of at least 30 kg/m2 are obese. However, significant numbers of people with a BMI below 30 kg/m2 are also obese and thus misclassified by BMI. Percent of body fat and body fat divided by height (m2) are predictable from BMI, but the accuracy of the prediction is lowest when the BMI is below 30 kg/m2. Therefore, measurement of body fat is a more appropriate way to assess obesity in people with a BMI below 30 kg/m2.

Validation of several established equations for resting metabolic rate in obese and nonobese people

OBJECTIVE To evaluate several equations for predicting resting metabolic rate against measured values in obese and nonobese people. DESIGN Resting metabolic rate was measured with indirect calorimetry. Four calculation standards using various combinations of weight, height, and age were used to predict resting metabolic rate: a) Harris-Benedict equation, b) Harris-Benedict equation using adjusted body weight in obese individuals, c) Owen, and d) Mifflin. Main outcome was percentage of subjects whose calculated metabolic rate was outside a +/-10% limit from measured values. Subjects/Setting 130 nonhospitalized adult volunteers grouped by degree of obesity (range of body mass index, 18.8 to 96.8). Statistical Analysis Performed Analysis of proportions was used to determine differences in the percentage of subjects estimated accurately by each equation; alpha was set at 0.05. RESULTS Calculated resting metabolic rate was more than 10% different from measured in 22% of subjects using the Mifflin equation, 33% using the Harris-Benedict equation (P=.05 vs Mifflin), and 35% using the Owen equation (P<.05 vs Mifflin). The error rate using Harris-Benedict with adjusted weight in obesity was 74% (vs 36% in obese subjects using actual weight in the standard Harris-Benedict equation). APPLICATIONS/CONCLUSION Of the calculation standards tested, the Mifflin standard provided an accurate estimate of actual resting metabolic rate in the largest percentage of nonobese and obese individuals and therefore deserves consideration as the standard for calculating resting metabolic rate in obese and nonobese adults. Use of adjusted body weight in the Harris-Benedict equation led to less overestimation by that equation in obese people at the expense of increased incidence of underestimation.

The Harris-Benedict Studies of Human Basal Metabolism: History and Limitations

In the early part of the 20th century, numerous studies of human basal metabolism were conducted at the Nutrition Laboratory of the Carnegie Institution of Washington in Boston, Mass, under the direction of Francis G. Benedict. Prediction equations for basal energy expenditure (BEE) were developed from these studies. The expressed purpose of these equations was to establish normal standards to serve as a benchmark for comparison with BEE of persons with various disease states such as diabetes, thyroid, and other febrile diseases. The Harris-Benedict equations remain the most common method for calculating BEE for clinical and research purposes. The widespread use of the equations and the relative inaccessibility of the original work highlights the importance of reviewing the data from which the standards were developed. A review of the data reveals that the methods and conclusions of Harris and Benedict appear valid and reasonable, albeit not error free. All of the variables used in the equations have sound physiologic basis for use in predicting BEE. Supplemental data from the Nutrition Laboratory indicates that the original equations can be applied over a wide range of age and body types. The commonly held assumption that the Harris-Benedict equations overestimate BEE in obese persons may not be true for persons who are moderately obese.

Remicade does not abolish the need for surgery in fistulizing Crohn's disease.

AbstractPURPOSE: Tumor necrosis factor antagonist therapy in the form of infliximab has been shown to promote significant healing in fistulizing Crohn’s disease and therefore is often considered as a possible alternative to surgery. Our aim was to evaluate the role of infliximab in supplanting surgery for fistulizing Crohn’s disease. METHODS: We performed a retrospective chart review of all adult patients who received infliximab for fistulizing Crohn’s disease at one institution between September 1998 and October 2000. RESULTS: Twenty-six patients (14 male; mean age, 38 years; range, 19–80 years) received a mean of three (range, one to six) doses of infliximab (5 mg/kg) with the intent to cure fistulizing Crohn’s disease. Nine patients (35 percent) had perianal, 6 (23 percent) enterocutaneous, 3 (12 percent) rectovaginal, 4 (15 percent) peristomal, and 4 (15 percent) intra-abdominal fistulas. Nineteen (73 percent) of the patients had had prior surgery for Crohn’ s disease. Six patients (23 percent) had a complete response to infliximab with fistula closure, 12 (46 percent) had a partial response, and 8 (31 percent) had no response to infliximab. Fourteen (54 percent) patients still required surgery for their fistulizing Crohn’s disease after infliximab therapy (10 bowel resections, 4 perianal procedures), whereas half (6/12) of the patients treated with infliximab who still had open fistulas after treatment declined surgical intervention. Five of six patients with fistula closure on infliximab had perianal or rectovaginal fistulas. None of the patients with either enterocutaneous or peristomal fistulas were healed with infliximab. CONCLUSIONS: Although it was associated with a 61 percent complete or partial response rate, infliximab therapy did not supplant the need for surgical intervention in the majority of our patients with fistulizing Crohn’s disease. Seventy-three percent of the patients either required surgery or still had open fistulas after infliximab therapy. Infliximab was much more effective in treating perianal disease than abdominal enterocutaneous disease.

Age-related differences in the metabolic response to injury.

OBJECTIVE To investigate the effect of age on the metabolic response to injury. METHODS Fifty-two trauma patients meeting entrance criteria were prospectively enrolled. Patients were grouped by age: elderly, >60 years; and young, < or =60 years. After 4 days of nutrition support, physiologic and laboratory data were collected. Energy and nitrogen metabolism, and body composition were evaluated. RESULTS Elderly patients demonstrated a reduced incidence of fever (48% vs. 77%,p = 0.027). Independent of body composition, temperature, and injury severity, oxygen consumption was 8% lower in the elderly (p = 0.0032). However, nitrogen loss and myofibrillar catabolic rate was not altered by age. Elderly subjects were more often hyperglycemic (38% vs. 0%, p < 0.0001) and azotemic (62% vs. 22%, p = 0.004), despite similar carbohydrate and protein intake. CONCLUSION Fever is less common and oxygen consumption lower in elderly trauma patients. Postinjury myofibrillar protein catabolism and nitrogen loss are not influenced by aging. Metabolic complications of nutrition support (hyperglycemia, azotemia) are more common in elderly trauma patients.

Intravenous Cyclosporine for the Treatment of Severe Steroid Refractory Ulcerative Colitis: What is the Cost?

PURPOSEIntravenous cyclosporine often is used to treat patients with severe steroid refractory colitis secondary to ulcerative colitis in an attempt to avoid urgent total abdominal colectomy. The purpose of this study was to evaluate the success and cost of cyclosporine.METHODSA retrospective, chart review of all patients from 1996 to 2002 who were treated with cyclosporine and/or had a three-stage ileal pouch-anal anastomosis for severe steroid refractory colitis at our institution was performed. Patients were divided into three groups: TAC and CyA: patients who failed cyclosporine and had urgent total abdominal colectomy on the same admission; TAC no CyA: patients who had an urgent total abdominal colectomy without cyclosporine; and CyA only: patients treated successfully with cyclosporine and discharged without surgery. A subgroup of patients who had an ileal pouch-anal anastomosis was identified from each group. Cost data were obtained from the hospital’s financial records.RESULTSForty-one patients (25 males) were identified. Twenty-nine patients received cyclosporine for severe steroid refractory colitis. Of these, 18 (62 percent) failed and underwent total abdominal colectomy on the same admission. Eleven (38 percent) responded to the cyclosporine and were discharged. Of the 11, 4 never had surgery, 1 had a three-stage ileal pouch-anal anastomosis, 5 had a two-stage ileal pouch-anal anastomosis, and 1 had a total abdominal colectomy only. Only 14 percent of patients avoided colectomy in the long-term. Complications of cyclosporine occurred in 8 patients (28 percent), and surgical complications occurred in 12 patients.CONCLUSIONSThe highest costs, highest length of stay, and highest number of overall complications were found in the group of patients who failed intravenous cyclosporine and required colectomy during the same hospitalization.