Using change in predicted adult height during GnRH agonist treatment for individualized treatment decisions in girls with central precocious puberty

Abstract Objectives It is important to understand what variables influence change in predicted adult height (PAH) throughout GnRHa treatment for central precocious puberty (CPP) to individualize treatment decisions and optimize care. Methods Changes in PAH, chronological age (CA), bone age (BA), BA/CA, and height velocity (HV) were evaluated in girls with CPP throughout treatment with leuprolide acetate (n=77). A second analysis focused on changes in the 3 years preceding the first observed BA of ≥12 years. Relationships were characterized using plot inspection and linear mixed-effects analyses. Association between treatment duration and last assessed PAH was examined using multiple linear regression models. Results BA/CA and HV showed a nonlinear change during treatment, with the largest changes and improvement in PAH observed in the first 6–18 months. Rate of BA advancement tended to decrease more slowly in girls initiating treatment at a younger BA. On-treatment change in PAH was predicted by concurrent BA/CA change, HV, and BA, as well as CA at treatment initiation. Last assessed PAH was positively associated with longer treatment durations (primary/exploratory models cut-offs of ≥33/≥55 months). Conclusions These findings support individualized monitoring during GnRHa treatment. Initial response should be interpreted with caution until 6–18 months after treatment initiation and failure should not be assumed based on continued bone maturation in girls starting therapy at a younger age. Treatment cessation should not be automatically based on a diminishing change in PAH or HV, as ongoing treatment may result in continued increase or maintenance of PAH.