Treatment of central precocious puberty: Lessons from a 15 years prospective trial

There is still controversy about the auxological outcome of GnRH agonist tr eatment in patients with CPP and about the favorable age and auxological ch aracteristics at start of treatment for achieving a normal final height (FH ) or for preserving height potential. We analyzed the FH data of 52 young w omen from a prospective multicentric trial which was started in 1985. The a im of this analysis was to determine factors that may predict a favorable F H 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 treatmen t, 11.1 +/- 1.1 yr at end of treatment, and 16.7 +/- 2.6 yr at FH evaluatio n. 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 Tn 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 i n 29% of patients (63% had an initial PAH < 156 cm). The group of patients with start of puberty at age less than or equal to 6 yr (Group 1) showed a significantly higher height gain (FH - initial PAH) and lower height defici t compared to Tn than older patients (Group 2). Furthermore, the percentage of patients from Group 1 reaching Tn range or mean TH showed a significant increase with GnRH agonist treatment whereas this was not the case in Grou p 2. Stepwise regression analysis showed that height SDS at end of treatmen t, age at menarche, bone age (BA) at start of treatment, and BA advancement at end of treatment were determinants of FH (r(2)=0.923). Initial BA advan cement and treatment duration were the factors that explained 68% of the va riability of height gain. Although BA advancement at initiation of treatmen t was negatively associated with FH it was a positive predictor of height g ain. In addition, height gain correlated significantly with CA and BA at st art of treatment (r=-0.430, p=0.004 and r=0.359, p=0.018). Growth after int erruption of treatment had no significant predictive effect on FH. It is co ncluded 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 n ormal FH. BA, BA advancement, and height SDS at treatment start are importa nt factors for determining outcome.