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.

Best practice guidelines regarding prenatal evaluation and delivery of patients with skeletal dysplasia

“…For example, though specific skeletal changes are present at birth in all infants with achondroplasia (ie, proximal femoral lucency, iliac flaring, interpedicular narrowing of lumbar vertebrae, metaphyseal flaring), such radiographs may not be obtained in the immediate perinatal period if rhizomesomelia and midface hypoplasia are mild and the newborn length falls within the normal range of average stature infants. As shown by Hoover-Fong et al 47 in a large cohort of achondroplasia patients, newborn length was on average within 1 cm of the reference infant cohort included in the 2000 Centers for Disease Control and Prevention growth charts. However, by 6 months of age, all overlap in length between the achondroplasias cohort and average stature infants had separated with all achondroplasia patients plotting significantly (e2.0 SD) below the mean.…”

Current knowledge of medical complications in adults with achondroplasia: A scoping review

“…Obesity and high BMI are frequently reported in achondroplasia . However, BMI and other anthropometric measurements are poor predictors of body fat and fat distribution, and even more in individuals of disproportionate short stature, such as achondroplasia .…”

“…Obesity and high BMI are frequently reported in achondroplasia. 18,22,32,[60][61][62][63] However, BMI and other anthropometric measurements are poor predictors of body fat and fat distribution, 64 and even more in individuals of disproportionate short stature, such as achondroplasia. 32,60,65 In a recently published paper, the authors found an atypical obesity with preferential abdominal obesity in achondroplasia children.…”

Height growth velocity during infancy and childhood in achondroplasia

“…In comparison with growth velocities of non-ACH children from the United States, in a sample processed with the same mathematical method, the growth velocity of ACH-children was lesser in magnitude (Berkey & Reed, 1987). This growth retardation during infancy, determine the severe growth deficit at 2 years of age for ACH children described in different populations (del Pino et al, 2010;Hoover-Fong et al, 2017;Merker et al, 2018;Tofts et al, 2017).…”

“…During infancy and childhood height falls progressively and in adolescents, is approximately 5.00 SDS below the 50th centile for Argentine and others non-ACH populations with a mean adult height of −6.42 and −6.72 SDS, for males and females, respectively (del Pino et al, 2010;Hoover-Fong, McGready, Schulze, Alade, & Scott, 2017;Lejarraga, del Pino, Fano, Caino, & Cole, 2009;Merker et al, 2018;Tofts, Das, Collins, & Burton, 2017).…”