Using Linear slope estimate as independent variable in regression analysis

Hi all,

I am doing an analysis of longitudinal growth data and would like to compare my methods to other studies but am having trouble finding others. Could someone please let me know if this method of using a MLE as a predictor in another regression is used in another field, (animal sci, econometrics, etc)

In my model we used a mixed model, maximum likelihood estimate of the slope of the SD value of height for age as the proxy for growth. This slope value, which was unique for each individual as it used both fixed and random effects, was then used as a predictor/indep variable in a regression assessing the contribution of growth on adult health outcomes.

Thanks for any help!