Protocol Overview

October 1, 2015

National Health and Nutrition Examination Survey 2007-2008 Anthropometry Procedures Manual

Measurement of the study subject subcutaneous fat mass using calipers to measure skinfold thickness over the triceps muscle. Skinfold thicknesses may also be measured at the number of other sites, including the midaxillary, pectoral, abdominal, anterior thigh, suprapatellar, medical calf, biceps, and forearm sites. If these latter sites are of interest, definitions and protocols are available in manuals that describe anthropometric measurements.

There are several overarching, critical issues for high-quality data collection of anthropometric measures that optimize the data in gene-environment etiologic research. These issues include: (1) the need for training (and re-training) of study staff in anthropometric data collection; (2) duplicate collection of measurements, especially under field conditions; (3) use of more than one person for proper collection of measurements where required; (4) accurate recording of the protocols and the measurement units of data collection; and (5) use of required and properly calibrated equipment.

The notion of recommending replicate measurements comes from the reduction in random errors of measurement and accompanying improved measurement reliability when the mean of multiple measurements is used rather than the a single measurement. This improvement in measurement reliability, however, depends upon the reliability of a single measurement in the hands of the data collectors in a particular study (Himes, 1989). For example, if a measure like recumbent length in a given study has a measurement reliability of 0.95 (expressed as an intraclass correlation coefficient), taking a second measurement and using the mean of the two in analyses will only improve the reliability to 0.97, yielding only a 2% reduction in error variance for the additional effort. If in the same study the reliability of a single triceps skinfold measurement was 0.85, using the mean including a replicate measurement would raise the reliability to 0.92 and yield a 7% reduction in error variance, more than a threefold improvement compared with recumbent length.Because the benefits of taking replicate measurements are so closely linked with the existing measurement reliability, it is recommended that as a part of the training of those who will be collecting anthropometry data, a reliability study be conducted that will yield measurement reliability estimates for the data collectors, protocols, settings and participants involved in that particular study (Himes, 1989). If the measurement reliability for a single measurement ≥ 0.95 the recommendation is that replicate measurement are not necessary and will yield little practical benefit. If the measurement reliability <0.95 the recommendation is to include replicate measurements as prescribed.

If replicate measurements are indicated because of relatively low reliability, a second measurement should be taken, including repositioning the participant. A third measurement should be taken if the first two measurements differ by >2.0 mm. If it is necessary to take a third measurement, the two closest measurements are averaged. If the third measurement falls equally between the first two measurements, all three should be averaged.

The Expert Review Panel notes that measurements should be made at the precision levels of the calipers chosen (dial graduation mark). Suggestions for acceptable calipers and their precision are given below.

Triceps Skinfold: The triceps skinfold is measured at the mid-point of the upper arm. The procedures for making this mark are explained in Upper Arm Length. Follow the procedures after that to perform the triceps skinfold measure.

Upper Arm Length

1. Position the participant: Direct the participant to turn away from you. Ask him or her to stand upright with weight evenly distributed on both feet, the right arm bent 90º at the elbow, and the right palm facing up. Demonstrate the correct position if necessary.

2. Mark the measurement site: Locate the end of the spine of the right scapula by following the scapula out to the arm until it makes a sharp V-turn to the front of the body. Using the cosmetic pencil, make a horizontal line on the uppermost edge of the posterior border of the spine extending from the acromion process (see Exhibit 1).

3. Take the measurement: Hold the zero end of the measuring tape at this mark and extend the tape down the posterior surface of the arm to the tip of the olecranon process, the bony part of the mid-elbow (Exhibit 2). Take the measurement to the nearest 0.1 cm. IMPORTANT: The tape must be centered on the posterior surface of the arm. Exhibit 2 shows the correct placement of the measuring tape centered on the posterior surface of the arm, whereas Exhibit 3 shows the measuring tape placed incorrectly.

4. Divide the measure in half to calculate the mid-point of the measured length. Make a horizontal mark at the mid-point and cross this mark with a perpendicular line (Exhibit 4). IMPORTANT: The vertical line must be centered on the posterior surface of the arm.

5. After marking the arm, the participant can relax his or her arm.

Export Variables

Variable Name	Variable ID	Variable Description	Version	Mapping
PX020303_BodyComposition_Tricep_Training	PX020303010000	Have the study staff undergone any training or retraining in anthropometric data collection?	4	N/A
PX020303_BodyComposition_Tricep_Duplicate_Measurements	PX020303020000	Will duplicate measurements taken?	4	N/A
PX020303_BodyComposition_Tricep_Adequate_Training	PX020303030000	Is the team adequately staffed so that more than one person is available for proper collection of measurements where required?	4	N/A
PX020303_BodyComposition_Tricep_Quality_Training	PX020303040000	Has the staff been properly trained to acquire an accurate recording of the protocols and measurements units of data collection?	4	N/A
PX020303_BodyComposition_Tricep_Proper_Equipment	PX020303050000	Has the staff been properly trained in the use of and have access to required and properly calibrated equipment?	4	N/A
PX020303_BodyComposition_Tricep_Subject_Instructions1	PX020303060000	Was the participant instructed to stand upright with weight evenly distributed on both feet, right arm bent 90 degrees at the elbow, and the right palm facing up?	4	N/A
PX020303_BodyComposition_Tricep_Halfway_Measurement_Marking	PX020303070000	After locating the end of the spine of the right scapula by following the scapula out to the arm until it makes a sharp V-turn to the front of the body, using a cosmetic pencil, was a horizontal line made at the uppermost edge of the posterior border of the spine extending from the acromion process (see exhibit 1)?	4	N/A
PX020303_BodyComposition_Tricep_Halfway_Measurement_Method	PX020303080000	Holding the zero end of the measuring tape at the horizontal line mark, was a measurement taken by extending the tape down the posterior surface of the arm to the tip of the olecranon process (the bony part of the elbow, exhibit 2)?	4	N/A
PX020303_BodyComposition_Tricep_Halfway_Measurement	PX020303090000	What was the measurement, to the nearest 0.1 cm?	4	N/A
PX020303_BodyComposition_Tricep_Halfway_Point	PX020303100000	After dividing the taken measurement in half, was a horizontal mark made at the mid-point?	4	N/A
PX020303_BodyComposition_Tricep_Subject_Instructions2	PX020303110000	Was the participant instructed to stand upright with weight evenly distributed on both feet, shoulders relaxed, and arms hanging loosely at the sides?	4	N/A
PX020303_BodyComposition_Tricep_Skinfold_Grasp_Method	PX020303120000	Using the thumb and index finger, was the fold of skin and subcutaneous adipose tissue grasped approximately 2.0 cm above the mid-arm circumference mark?	4	N/A
PX020303_BodyComposition_Tricep_Measurement_Method1	PX020303130000	While holding the skinfold 2.0 cm above the circumference mark, were the tips of the calipers placed over the complete skinfold?	4	N/A
PX020303_BodyComposition_Tricep_Measurement_Method2	PX020303140000	While holding the skinfold 2.0 cm above the circumference mark, was the caliper handle released to exert full tension on the skinfold for at least 3 seconds before a measurement was taken?	4	N/A
PX020303_BodyComposition_Tricep_Measurement	PX020303150000	What was the thickness of the skinfold to the nearest 0.2 mm?	4	N/A

Throughout all of the cycles where skinfolds were collected, National Health and Nutrition Examination Survey (NHANES) kept to a rigorous training and reliability schedule for their anthropometrists, and the NHANES protocols are consistent with best practices in the field. Skinfold-based measures of fatness and fat distribution in children and adults have been consistently found to agree better with fatness and fat distribution measured by dual-energy x-ray absorptiometry (DXA) than other commonly used indices of body composition, e.g., body mass index (BMI) and waist-to-hip ratio (WHR), that are collected in field situations.

Centers for Disease Control and Prevention (CDC), National Center for Health Statistics (NCHS). (2007). National Health and Nutrition Examination Survey 2007-2008 Anthropometry Procedures Manual. Retrieved from http://www.cdc.gov/nchs/data/nhanes/nhanes_07_08/manual_an.pdf

Infant, Toddler, Child, Adolescent, Adult, Senior

English

Participants at all ages, including neonates

Trained to use skinfold calipers, NHANES training video available at: http://www.cdc.gov/nchs/nhanes/nhanes3/anthropometric_videos.htm

Skinfold caliper, the type of caliper used should be recorded. A table of commonly used skinfold calipers appears below.

Standard	Name	ID	Source
Common Data Elements (CDE)	Person Triceps Skinfold Thickness Body Composition Percentage Value	5020451	CDE Browser

Addo, O. Y., & Himes, J. H. (2014). Are field measures of adiposity sufficient to establish fatness-related linkages with metabolic outcomes in adolescents. Eur J Clin Nutr, 68(6), 671-676. doi: 10.1038/ejcn.2014.14

Addo, O. Y., Pereira, M. A., & Himes, J. H. (2012). Is skinfold thickness as good as DXA when measuring adiposity contributions to insulin resistance in adolescents? Amer J Hum Bio, 24(6), 806-811. doi: 10.1002/ajhb.22321

Fosbol, M., & Zehran, B. (2014). Contemporary methods of body composition measurement. Clinical Physiology and Functional Imaging, 35(2), 81-97. doi:1111/cpf.12152.

Himes, J. H. (1989). Reliability of anthropometric methods and replicate measurements. American Journal of Physical Anthropology, 79(1), 77-80.

Ketel, I. J. G., Volman, M. N. M., Seidell, J. C., Stehouwer, C. D. A., Twisk, J. W., & Lambalk, C. B. (2007). Superiority of skinfold measurements and waist over waist-to-hip ratio for determination of body fat distribution in a population-based cohort of Caucasian Dutch adults. Eur J Endocr, 156(6), 655-661. doi: 10.1530/eje-06-0730

Lohman, T. G., Roche, A. F., & Martorell, R. (1988). Anthropometric standardization reference manual (31, pp. 1493-1494). Champaign, IL, Human Kinetics Books.

Ward, L. C., Poston, L., Godfrey, K. M., & Koletzko, B. (2013). Assessing early growth and adiposity: Report from an Early Nutrition Academy workshop. Annals of Nutrition and Metabolism, 63(1-2), 120-130. doi:10.1159/000350702

Wang, J., Thornton, J. C., Kolesnik, S., Pierson, R. N., Jr. (2000). Anthropometry in body composition. An overview. Annals of the New York Academy of Science, 904, 317-326.

Wells, J. C. K. (2014). Toward Body Composition Reference Data for Infants, Children, and Adolescents. Advances in Nutrition: An International Review Journal, 5(3), 320S-329S. doi: 10.3945/an.113.005371

Wohlfahrt-Veje, C., Tinggaard, J., Winther, K., Mouritsen, A., Hagen, C. P., Mieritz, M. G., . . . Main, K. M. (2014). Body fat throughout childhood in 2647 healthy Danish children: agreement of BMI, waist circumference, skinfolds with dual X-ray absorptiometry. Eur J Clin Nutr, 68(6), 664-670. doi: 10.1038/ejcn.2013.282

Physical Measurement

Centripetal Fat Ratio (CFR), % Body Fat (various equations)

Requirement Category	Required
Average time of greater than 15 minutes in an unaffected individual	No
Major equipment	No
Specialized requirements for biospecimen collection	No
Specialized training	No

The Expert Review Panel #1 reviewed the measures in the Anthropometrics, Diabetes, Physical Activity and Physical Fitness, and Nutrition and Dietary Supplements domains.

Guidance from the ERP includes:

• Added a new protocol

• New Data Dictionary