title: Arm span and ulnar length are reliable and accurate estimates of recumbent length and height in a multiethnic population of infants and children under 6 years of age.
abstract: Surrogate measures are needed when recumbent length or height is unobtainable or unreliable. Arm span has been used as a surrogate but is not feasible in children with shoulder or arm contractures. Ulnar length is not usually impaired by joint deformities, yet its utility as a surrogate has not been adequately studied. In this cross-sectional study, we aimed to examine the accuracy and reliability of ulnar length measured by different tools as a surrogate measure of recumbent length and height. Anthropometrics [recumbent length, height, arm span, and ulnar length by caliper (ULC), ruler (ULR), and grid (ULG)] were measured in 1479 healthy infants and children aged <6 y across 8 study centers in the United States. Multivariate mixed-effects linear regression models for recumbent length and height were developed by using ulnar length and arm span as surrogate measures. The agreement between the measured length or height and the predicted values by ULC, ULR, ULG, and arm span were examined by Bland-Altman plots. All 3 measures of ulnar length and arm span were highly correlated with length and height. The degree of precision of prediction equations for length by ULC, ULR, and ULG (R(2) = 0.95, 0.95, and 0.92, respectively) was comparable with that by arm span (R(2) = 0.97) using age, sex, and ethnicity as covariates; however, height prediction by ULC (R(2) = 0.87), ULR (R(2) = 0.85), and ULG (R(2) = 0.88) was less comparable with arm span (R(2) = 0.94). Our study demonstrates that arm span and ULC, ULR, or ULG can serve as accurate and reliable surrogate measures of recumbent length and height in healthy children; however, ULC, ULR, and ULG tend to slightly overestimate length and height in young infants and children. Further testing of ulnar length as a surrogate is warranted in physically impaired or nonambulatory children.
authors.affiliation: Department of Nutritional Sciences, School of Human Ecology, University of Texas at Austin, Austin, TX mforman@austin.utexas.edu.
authors.forename: Michele R
authors.initials: MR
authors.lastname: Forman
authors.affiliation: Department of Nutritional Sciences, School of Human Ecology, University of Texas at Austin, Austin, TX.
authors.forename: Yeyi
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: Department of Nutritional Sciences, School of Human Ecology, University of Texas at Austin, Austin, TX.
authors.forename: Ladia M
authors.initials: LM
authors.lastname: Hernandez
authors.affiliation: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN.
authors.forename: John H
authors.initials: JH
authors.lastname: Himes
authors.affiliation: Department of Nutritional Sciences, School of Human Ecology, University of Texas at Austin, Austin, TX.
authors.forename: Yongquan
authors.initials: Y
authors.lastname: Dong
authors.affiliation: Department of Pediatrics, the University of Texas Health Science Center at San Antonio, San Antonio, TX.
authors.forename: Robert K
authors.initials: RK
authors.lastname: Danish
authors.affiliation: Department of Nutritional Sciences, School of Human Ecology, University of Texas at Austin, Austin, TX.
authors.forename: Kyla E
authors.initials: KE
authors.lastname: James
authors.affiliation: Center for Human Nutrition, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Caulfield
authors.affiliation: Department of Epidemiology and Biostatistics, Michigan State University, East Lansing, MI.
authors.forename: Jean M
authors.initials: JM
authors.lastname: Kerver
authors.affiliation: David Geffen School of Medicine, University of California, Los Angeles, CA.
authors.forename: Lenore
authors.initials: L
authors.lastname: Arab
authors.affiliation: University of California, Irvine, CA.
authors.forename: Paula
authors.initials: P
authors.lastname: Voss
authors.affiliation: Department of Pediatrics, the University of Texas Health Science Center at San Antonio, San Antonio, TX.
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Hale
authors.affiliation: Department of Pediatrics, School of Medicine, Saint Louis University, St. Louis, MO; and.
authors.forename: Nadim
authors.initials: N
authors.lastname: Kanafani
authors.affiliation: Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD.
authors.forename: Steven
authors.initials: S
authors.lastname: Hirschfeld
mesh_terms: D000886:Anthropometry / Q000379:methods*; D001132:Arm; D001827:Body Height / Q000208:ethnology; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D015203:Reproducibility of Results; D014457:Ulna; D014481:United States