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Title: Enhancing a somatic maturity prediction model
Authors: Moore, Sarah A.
McKay, Heather A.
MacDonald, Heather
Nettlefold, Lindsay
Baxter-Jones, Adam D.G.
Cameron, Noel
Brasher, Penelope M.A.
Issue Date: 2015
Publisher: © American College of Sports Medicine. Published by Lippincourt Williams & Wilkins
Citation: MOORE, S.A. ...et al., 2015. Enhancing a Somatic Maturity Prediction Model. Medicine and Science in Sports and Exercise, 47(8), pp. 1755-1764.
Abstract: Purpose: Assessing biological maturity in studies of children is challenging. Sex-specific regression equations developed using anthropometric measures are widely used to predict somatic maturity. However, prediction accuracy was not established in external samples. Thus, we aimed to evaluate the fit of these equations, assess for overfitting (adjusting as necessary), and calibrate using external samples. Methods: We evaluated potential overfitting using the original Pediatric Bone Mineral Accrual Study (PBMAS; 79 boys and 72 girls; 7.5–17.5 yr). We assessed change in R2 and standard error of the estimate (SEE) with the addition of predictor variables. We determined the effect of within-subject correlation using cluster-robust variance and fivefold random splitting followed by forward-stepwise regression. We used dominant predictors from these splits to assess predictive abilities of various models. We calibrated using participants from the Healthy Bones Study III (HBS-III; 42 boys and 39 girls; 8.9–18.9 yr) and Harpenden Growth Study (HGS; 38 boys and 32 girls; 6.5–19.1 yr). Results: Change in R2 and SEE was negligible when later predictors were added during step-by-step refitting of the original equations, suggesting overfitting. After redevelopment, new models included age × sitting height for boys (R2, 0.91; SEE, 0.51) and age × height for girls (R2, 0.90; SEE, 0.52). These models calibrated well in external samples; HBS boys: b0, 0.04 (0.05); b1, 0.98 (0.03); RMSE, 0.89; HBS girls: b0, 0.35 (0.04); b1, 1.01 (0.02); RMSE, 0.65; HGS boys: b0, −0.20 (0.02); b1, 1.02 (0.01); RMSE, 0.85; HGS girls: b0, −0.02 (0.03); b1, 0.97 (0.02); RMSE, 0.70; where b0 equals calibration intercept (standard error (SE)) and b1 equals calibration slope (SE), and RMSE equals root mean squared error (of prediction). We subsequently developed an age × height alternate for boys, allowing for predictions without sitting height. Conclusion: Our equations provided good fits in external samples and provide an alternative to commonly used models. Original prediction equations were simplified with no meaningful increase in estimation error.
Description: This paper is in closed access.
Sponsor: This study received funding support from a number of agencies. The HBS-III was supported by the Canadian Institute for Health Research (CIHR; MOP-84575), the Michael Smith Foundation for Health Research (MSFHR), the British Columbia Ministry of Health, and 2010 Legacies Now. PBMAS was supported by the Canadian National Health and Research Development Program (NHRDP; 6608-1261) and CIHR (MOP-57671, MOP-83391, and MOP-85582).
Version: Published
DOI: 10.1249/MSS.0000000000000588
URI: https://dspace.lboro.ac.uk/2134/19605
Publisher Link: http://dx.doi.org/10.1249/MSS.0000000000000588
ISSN: 0195-9131
Appears in Collections:Closed Access (Sport, Exercise and Health Sciences)

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