A mechanistic approach to tracing anthropometric charts: the extended mechanistic growth function method.

OBJECTIVES: The Extended Mechanistic Growth Function (EMGF) method (Clementi et al. [1999]: Am J Med Genet 87:317-323) is a possible alternative to the Cole and Green LMS method ([1992] Stat Med 11:1305-1319) to construct cross-sectional anthropometric charts. It differs from the technique used by Kuczmarski et al. ([2002]: Vital Health Stat 11:1-190) to trace the CDC growth charts in that all centiles are simultaneously fitted with a single function. The aim of this study is to show how an EMGF model can be designed. METHODS: To illustrate the structure and properties of the EMGF method, the data of the Italian Neonatal Study (Bertino et al. [2010]: J Pediatr Gastroenterol Nutr 51:353-361) were analyzed. The dataset included the birth weight of 45,272 single liveborn babies with gestational ages ranging from 23 to 42 weeks. The EMGF method consists of three steps. In the preliminary step, selected age-dependent raw centiles of the anthropometric trait are computed. In the smoothing step, all centiles are simultaneously fitted with a growth function extended with the inclusion of a few extra parameters. In the transformation step, estimates of the age-dependent L (skewness), M (median), and S (coefficient of variation) parameters are derived. RESULTS: A four-parameter generalized logistic function, extended with five parameters to model between-sex differences, distance between centiles and their slope, was found to fit the raw centiles of birth weight distribution with a residual standard deviation of 51.3 g. CONCLUSIONS: The EMGF method represents a bridge to link cross-sectional and longitudinal studies and allows us to identify milestones of the median growth in a population in the same way used for individual profiles.

Neonatal anthropometric charts: the Italian neonatal study compared with other European studies.

BACKGROUND AND OBJECTIVE: This was a nationwide prospective study carried out in Italy between 2005 and 2007, involving 34 centers with a neonatal intensive care unit. The study reports the Italian Neonatal Study charts for weight, length, and head circumference of singletons born between 23 and 42 gestational weeks, comparing them with previous Italian data and with the most recent data from European countries. PATIENTS AND METHODS: Single live born babies with ultrasound assessment of gestational age within the first trimester, and with both parents of Italian origin. Only fetal hydrops and major congenital anomalies diagnosed at birth were excluded. The reference set consists of 22,087 girls and 23,375 boys. RESULTS: At each gestational age, boys are heavier than girls by about 4%. Later-born neonates are heavier than firstborn neonates by about 3%. The effects of sex and birth order on length and head circumference are milder. No differences were observed between babies born in central-north Italy and southern Italy. A large variability emerged among European neonatal charts, resulting in huge differences in the percentage of Italian Neonatal Study neonates below the 10th centile, which is traditionally used to define small-for-gestational-age babies. In the last 2 decades prominent changes in the distribution of birth weight emerged in Italy and in the rest of Europe, in both term and preterm neonates. CONCLUSIONS: The existing European neonatal charts, based on more or less recent data, were found to be inappropriate for Italy. Until an international standard is developed, the use of national updated reference charts is recommended.

Correction to: Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?

An Online First version of this article was made available online at https://link.springer.com/article/10.1007%2Fs40279-017-0799-7 on 29 October 2017. Errors were subsequently identified in the article, and the following corrections should be noted.

Tanner-Whitehouse Skeletal Ages in Male Youth Soccer Players: TW2 or TW3?

BACKGROUND: The Tanner-Whitehouse radius-ulna-short bone protocol (TW2 RUS) for the assessment of skeletal age (SA) is widely used to estimate the biological (skeletal) maturity status of children and adolescents. The scale for converting TW RUS ratings to an SA has been revised (TW3 RUS) and has implications for studies of youth athletes in age-group sports. OBJECTIVES: The aim of this study was to compare TW2 and TW3 RUS SAs in an international sample of male youth soccer players and to compare distributions of players by maturity status defined by each SA protocol. METHODS: SA assessments with the TW RUS method were collated for 1831 male soccer players aged 11-17 years from eight countries. RUS scores were converted to TW2 and TW3 SAs using the appropriate tables. SAs were related to chronological age (CA) in individual athletes and compared by CA groups. The difference of SA minus CA with TW2 SA and with TW3 SA was used to classify players as late, average, or early maturing with each method. Concordance of maturity classifications was evaluated with Cohen's Kappa coefficients. RESULTS: For the same RUS score, TW3 SAs were systematically and substantially reduced compared with TW2 SAs; mean differences by CA group ranged from - 0.97 to - 1.16 years. Kappa coefficients indicated at best fair concordance of TW2 and TW3 maturity classifications. Across the age range, 42% of players classified as average with TW2 SA were classified as late with TW3 SA, and 64% of players classified as early with TW2 SA were classified as average with TW3 SA. CONCLUSION: TW3 SAs were systematically lower than corresponding TW2 SAs in male youth soccer players. The differences between scales have major implications for the classification of players by maturity status, which is central to some talent development programs.