title: A height-for-age growth reference for children with achondroplasia: Expanded applications and comparison with original reference data.
abstract: The height-for-age (HA) reference currently used for children with achondroplasia is not adaptable for electronic records or calculation of HA Z-scores. We report new HA curves and tables of mean and standard deviation (SD) HA, for calculating Z-scores, from birth-16 years in achondroplasia. Mixed longitudinal data were abstracted from medical records of achondroplasia patients from a single clinical practice (CIS, 1967-2004). Gender-specific height percentiles (5, 25, 50, 75, 95th) were estimated across the age continuum, using a 2 month window per time point smoothed by a quadratic smoothing algorithm. HA curves were constructed for 0-36 months and 2-16 years to optimize resolution for younger children. Mean monthly height (SD) was tabulated. These novel HA curves were compared to reference data currently in use for children with achondroplasia. 293 subjects (162 male/131 female) contributed 1,005 and 932 height measures, with greater data paucity with age. Mean HA tracked with original achondroplasia norms, particularly through mid-childhood (2-9 years), but with no evidence of a pubertal growth spurt. Standard deviation of height at each month interval increased from birth through 16 years. Birth length was lower in achondroplasia than average stature and, as expected, height deficits increased with age. A new HA reference is available for longitudinal growth assessment in achondroplasia, taking advantage of statistical modeling techniques and allowing for Z-score calculations. This is an important contribution to clinical care and research endeavors for the achondroplasia population.
authors.affiliation: Greenberg Center for Skeletal Dysplasias, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Julie
authors.identifier: http://orcid.org/0000-0002-1242-5626
authors.initials: J
authors.lastname: Hoover-Fong
authors.affiliation: Department of Biostatistics, Johns Hopkins University, Baltimore, Maryland.|Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.
authors.forename: John
authors.initials: J
authors.lastname: McGready
authors.affiliation: Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.|Center for Human Nutrition, Department of International Health, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Kerry
authors.initials: K
authors.lastname: Schulze
authors.affiliation: Greenberg Center for Skeletal Dysplasias, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Adekemi Yewande
authors.initials: AY
authors.lastname: Alade
authors.affiliation: AI DuPont Hospital for Children, Sidney Kimmel Medical College, Thomas Jefferson University, Wilmington, Delaware.
authors.forename: Charles I
authors.initials: CI
authors.lastname: Scott
mesh_terms: D000130:Achondroplasia / Q000453:epidemiology* / Q000503:physiopathology*; D000293:Adolescent; D000367:Age Factors; D000886:Anthropometry; D001827:Body Height; D001835:Body Weight; D002648:Child; D002675:Child, Preschool; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male
keywords: achondroplasia; anthropometry; growth; growth curve; height-age