Nahhas R.W.,Lifespan Health Research Center |
Sherwood R.J.,Lifespan Health Research Center |
Sherwood R.J.,Wright State University |
Sherwood R.J.,Case Western Reserve University |
And 4 more authors.
Annals of Human Biology | Year: 2013
Background: Evaluation of skeletal maturity provides clinicians and researchers a window into the developmental progress of the skeleton. The FELS method for maturity assessment provides a point estimate and standard error based on 98 skeletal indicators. Aim: This paper outlines the statistical methodology used by the original FELS method and evaluates improvements that address the following: serial correlation in the calibration sample is now considered, a Bayesian estimation method is now employed to improve estimation near ages 0 and 18 years and uncertainty in the calibration due to sampling is now accounted for when computing confidence limits. Subjects and methods: The original FELS method was calibrated using 677 Fels Longitudinal Study participants. In the improved method, serial correlation is accounted for using GEE, a Bayesian analysis with a prior centred on chronological age is used and the bootstrap is used to account for all sources of variation. Results: Accounting for serial correlation resulted in larger slopes for ordinal indicators. The Bayesian paradigm led to narrower confidence limits and a natural interpretation of skeletal age. Sampling variability in the calibration parameters was negligible. Conclusion: Improvements to the statistical basis of the FELS method provide a more effective method of estimating skeletal maturity. © 2013 Informa UK Ltd.
PubMed | The Green Way, University of Oxford, United Arab Emirates University, Ludwig Institute for Cancer Research and Lifespan Health Research Center
Type: Journal Article | Journal: BMC pediatrics | Year: 2016
Crown-heel length (CHL) measurement is influenced by technique, training, experience and subject cooperation. We investigated whether extending one or both of an infants legs affects the precision of CHL taken using an infantometer. The influence of staff training and infant cooperation were also examined.CHL was measured in children (aged 2), infants (aged 1) and newborns, by extending one or both legs. The subjects level of cooperation was recorded. Mean differences were compared using Students t-test; intra- and inter-observer variability were assessed using Bland-Altman plots with 95% limits of agreement. Intra- and inter-observer technical errors of measurement (TEMs) were also calculated.Measuring CHL in newborns using only one leg resulted in significantly longer measurements. Across all groups, there was less inter-observer variability using both legs; 95% limits of agreement were lower and TEMs smaller. Larger measurement differences were seen if children were uncooperative.This study supports measuring CHL with both legs extended. The two-leg technique reduces variability and increases precision by allowing the measurer to control better the position and movements of the infants body.