Treatment of central precocious puberty: lessons from a 15 years prospective trial. German Decapeptyl Study Group.

There is still controversy about the auxological outcome of GnRH agonist treatment in patients with CPP and about the favorable age and auxological characteristics at start of treatment for achieving a normal final height (FH) or for preserving height potential. We analyzed the FH data of 52 young women from a prospective multicentric trial which was started in 1985. The aim of this analysis was to determine factors that may predict a favorable FH or a good height gain. Chronological age (CA) was 5.2 +/- 2.1 yr (+/- SD) at start of puberty, 6.2 +/- 2.0 yr at start of triptorelin depot treatment, 11.1 +/- 1.1 yr at end of treatment, and 16.7 +/- 2.6 yr at FH evaluation. After 4.8 +/- 2.2 yr (1.1-9.9 yr) of treatment duration, FH was 160.6 +/- 8.0 cm (vs 154.9 +/- 9.6 cm of initial height prediction [PAH], p<0.05). A FH within TH range or in excess of mean TH was achieved by 78% or 41% of patients. FH was above the 3rd percentile of the normal German population in 29% of patients (63% had an initial PAH < 156 cm). The group of patients with start of puberty at age < or = 6 yr (Group 1) showed a significantly higher height gain (FH - initial PAH) and lower height deficit compared to TH than older patients (Group 2). Furthermore, the percentage of patients from Group 1 reaching TH range or mean TH showed a significant increase with GnRH agonist treatment whereas this was not the case in Group 2. Stepwise regression analysis showed that height SDS at end of treatment, age at menarche, bone age (BA) at start of treatment, and BA advancement at end of treatment were determinants of FH (r2=0.923). Initial BA advancement and treatment duration were the factors that explained 68% of the variability of height gain. Although BA advancement at initiation of treatment was negatively associated with FH it was a positive predictor of height gain. In addition, height gain correlated significantly with CA and BA at start of treatment (r= -0.430, p=0.004 and r=0.359, p=0.018). Growth after interruption of treatment had no significant predictive effect on FH. It is concluded that a higher percentage of patients below 6 yr of age at start of puberty do profit from GnRH agonist treatment with respect to achieving a normal FH. BA, BA advancement, and height SDS at treatment start are important factors for determining outcome.