Protocol Overview

October 1, 2015

National Health and Nutrition Examination Survey III, 1988 Anthropometry Procedures Manual

Measurement of the study subject subcutaneous fat mass using calipers to measure skinfold thickness over the suprailiac site. 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 measurement.

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 three-fold better 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 >3.0 mm. If it is necessary to take a third measurement, the two closest measurements are averaged. Should the third measurement fall 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.

Suprailiac Skinfold:

The participant stands and holds the right side of the exam gown up so that the right hip area is exposed. It may be necessary to lower the exam pants slightly to expose the area. The examiner stands behind the participant and palpates the hip area for the right iliac crest. The examiner marks a horizontal line at the high point of the iliac crest and then crosses the line to indicate the midaxillary. The examiner places his/her thumb (left) on the intersecting marks and picks up the skinfold with the thumb and fingers. The skinfold should slope downward and forward at a 45º angle extending toward the pubic symphysis (see Exhibit 1). The caliper is placed perpendicular to the skinfold about 2.0 cm medial to the fingers and the skinfold is measured to the nearest 0.2 mm.

Exhibit 1. Location of suprailiac skinfold

Export Variables

Variable Name	Variable ID	Variable Description	Version	Mapping
PX020305_BodyComposition_Suprailiac_Training	PX020305010000	Have the study staff undergone any training or retraining in anthropometric data collection?	4	N/A
PX020305_BodyComposition_Suprailiac_Duplicate_Measurements	PX020305020000	Will duplicate measurements taken?	4	N/A
PX020305_BodyComposition_Suprailiac_Adequate_Training	PX020305030000	Is the team adequately staffed so that more than one person is available for proper collection of measurements where required?	4	N/A
PX020305_BodyComposition_Suprailiac_Quality_Training	PX020305040000	Has the staff been properly trained to acquire an accurate recording of the protocols and measurements units of data collection?	4	N/A
PX020305_BodyComposition_Suprailiac_Proper_Equipment	PX020305050000	Has the staff been properly trained in the use of and have access to required and properly calibrated equipment?	4	N/A
PX020305_BodyComposition_Suprailiac_Subject_Instructions	PX020305060000	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
PX020305_BodyComposition_Suprailiac_Marking_Method	PX020305070000	Did the examiner stand behind the subject, palpate the hip area for the right iliac crest, and then mark a horizontal line at the high point of the iliac crest and then cross the line to indicate the midaxillary?	4	N/A
PX020305_BodyComposition_Suprailiac_Grasping_Method	PX020305080000	Did the examiner grasp the skinfold with his thumb and index finger at the intersecting mark?	4	N/A
PX020305_BodyComposition_Suprailiac_Caliper_Method	PX020305090000	Was a caliper placed perpendicular to the skinfold, which should have been sloping downward and forawrd at a 45 degree angle extending toward the pubis symphysis, about 2.0 cm medial to the fingers?	4	N/A
PX020305_BodyComposition_Suprailiac_Measurement	PX020305100000	What is the caliper measurement to the nearest 0.2 mm?	4	N/A

Throughout all of the cycles where skinfolds were collected, 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). National Health and Nutrition Examination Survey III, 1988 Anthropometry Procedures Manual Available at http://www.cdc.gov/nchs/data/nhanes/nhanes3/cdrom/nchs/manuals/anthro.pdf

Infant, Toddler, Child, Adolescent, Adult, Senior

English

Participants aged 2 months and older; the comparable skinfold for neonates is the flank skinfold

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 Suprailiac Skinfold Thickness Body Composition Percentage Value	5021276	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

None

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:

a. Added a new protocol

b. New Data Dictionary