title: Practical Application of Linear Growth Measurements in Clinical Research in Low- and Middle-Income Countries.
abstract: OBJECTIVE
  Childhood stunting is a prevalent problem in low- and middle-income countries and is associated with long-term adverse neurodevelopment and health outcomes. In this review, we define indicators of growth, discuss key challenges in their analysis and application, and offer suggestions for indicator selection in clinical research contexts.
  
  
  METHODS
  Critical review of the literature.
  
  
  RESULTS
  Linear growth is commonly expressed as length-for-age or height-for-age z-score (HAZ) in comparison to normative growth standards. Conditional HAZ corrects for regression to the mean where growth changes relate to previous status. In longitudinal studies, growth can be expressed as ΔHAZ at 2 time points. Multilevel modeling is preferable when more measurements per individual child are available over time. Height velocity z-score reference standards are available for children under the age of 2 years. Adjusting for covariates or confounders (e.g., birth weight, gestational age, sex, parental height, maternal education, socioeconomic status) is recommended in growth analyses.
  
  
  CONCLUSIONS
  The most suitable indicator(s) for linear growth can be selected based on the number of available measurements per child and the child's age. By following a step-by-step algorithm, growth analyses can be precisely and accurately performed to allow for improved comparability within and between studies.
authors.affiliation: Department of Pediatrics, Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Jan M
authors.initials: JM
authors.lastname: Wit
authors.affiliation: Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: John H
authors.initials: JH
authors.lastname: Himes
authors.affiliation: Netherlands Organization for Applied Scientific Research TNO, Leiden, the Netherlands.|Department of Methodology and Statistics, Faculty of Social and Behavioral Sciences, University of Utrecht, Utrecht, the Netherlands.
authors.forename: Stef
authors.initials: S
authors.lastname: van Buuren
authors.affiliation: Departments of Pediatrics and Global Health, University of Washington, Seattle, Washington, USA.
authors.forename: Donna M
authors.initials: DM
authors.lastname: Denno
authors.affiliation: Department of Pediatrics and Hubert Department of Global Health, Emory University, Atlanta, Georgia, USA.
authors.forename: Parminder S
authors.initials: PS
authors.lastname: Suchdev
mesh_terms: D000886:Anthropometry; D001724:Birth Weight / Q000502:physiology*; D001827:Body Height / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D057238:Growth Charts; D006130:Growth Disorders / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D012923:Social Class
keywords: Anthropometry; Biomarker; Environmental enteric dysfunction; Growth; Stunting