MOESM1 of Decision trees in epidemiological research

Additional file 1. Regression tree representing the relationship between adjusted residuals for energy intake (adjusted for age, sex, and BMI) and 22 baseline covariate

Prediction of Body Mass Index Using Concurrently Self-Reported or Previously Measured Height and Weight

<div><p>Objective</p><p>To compare alternative models for the imputation of BMI_M (measured weight in kilograms/measured height in meters squared) in a longitudinal study.</p><p>Methods</p><p>We used data from 11,008 adults examined at wave III (2001–2002) and wave IV (2007–2008) in the National Longitudinal Study of Adolescent to Adult Health. Participants were asked their height and weight before being measured. Equations to predict wave IV BMI_M were developed in an 80% random subsample and evaluated in the remaining participants. The validity of models that included BMI constructed from previously measured height and weight (BMI_PM) was compared to the validity of models that used BMI calculated from concurrently self-reported height and weight (BMI_SR). The usefulness of including demographics and perceived weight category in those models was also examined.</p><p>Results</p><p>The model that used BMI_SR, compared to BMI_PM, as the only variable produced a larger R² (0.913 vs. 0.693), a smaller root mean square error (2.07 vs. 3.90 kg/m²) and a lower bias between normal-weight participants and those with obesity (0.98 vs. 4.24 kg/m²). The performance of the model containing BMI_SR alone was not substantially improved by the addition of demographics, perceived weight category or BMI_PM.</p><p>Conclusions</p><p>Our work is the first to show that concurrent self-reports of height and weight may be more useful than previously measured height and weight for imputation of missing BMI_M when the time interval between measures is relatively long. Other time frames and alternatives to in-person collection of self-reported data need to be examined.</p></div

MSD between predicted BMI_M and actual BMI_M by weight status in the test dataset (n = 2202).

<p>(A) Abbreviations: MSD for mean signed difference; BMI for body mass index, BMI_PM is derived from measured height and weight at wave III, BMI_M is derived from measured height and weight at wave IV, BMI_SR is constructed from self-reported height and weight at wave IV. (B) MSD was calculated as the mean of predicted BMI_M minus actual BMI_M. The dashed lines in the Fig are at ±0.5 kg/m². (C) Weight status was based on BMI_M. n = 719 for normal weight group (18.5≤ BMI_M <25 kg/m²) and n = 776 for the group with obesity (BMI_M ≥30kg/m²). Results for underweight group (n = 45) and for overweight group (n = 662) were not shown.</p

R² and RMSE from regression^* of predicted BMI_M against actual BMI_M in the test dataset.

<p>R² and RMSE from regression^{<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167288#t002fn002" target="_blank">*</a>} of predicted BMI_M against actual BMI_M in the test dataset.</p