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Department of Pediatrics (S.A.v.G., J.M.W.), Leiden University Medical Center, 2333 ZA Leiden, The Netherlands; Tergooi Hospital (G.A.K.), 1250 CA Blaricum, The Netherlands; Department of Developmental Psychology (H.V.-v.B.), Utrecht University, 3508 TA Utrecht, The Netherlands; Subdivision Endocrinology (D.M., S.M.P.F.d.M.K.-S.), Erasmus University Medical Center/Sophia Childrens Hospital, 3015 GJ Rotterdam, The Netherlands; Catharina Hospital (J.J.J.W.), 5623 EJ Eindhoven, The Netherlands; University Medical Center Utrecht/Wilhelmina Childrens Hospital (M.J., L.V.-W., H.V.-v.B.), 3508 AB Utrecht, The Netherlands; Departments of Pediatrics (H.A.D.-v.d.W.) and Radiology (J.C.R.), VU University Medical Center, 1007 MB Amsterdam, The Netherlands; and Diagnostic Center Eindhoven (G.L.), 5611 NE Eindhoven, The Netherlands
Address all correspondence and requests for reprints to: Dr. S. A. van Gool, Leiden University Medical Center, Department of Pediatrics, J6-S, Albinusdreef 2, 2333 ZA Leiden, The Netherlands. E-mail: s.van_gool{at}lumc.nl.
| Abstract |
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Design and Patients: Thirty-two adolescents with Tanner stage 23, age and bone age (BA) less than 12 yr for girls or less than 13 yr for boys, height SD score (SDS) less than 2.0 SDS or between 1.0 and 2.0 SDS plus a predicted adult height (PAH0) less than 2.0 SDS were randomly allocated to receive GH plus GnRHa (n = 17) or no treatment (n = 15) for 3 yr. FH was assessed at the age of 18 yr or older in girls or 19 yr or older in boys.
Results: FH was not different between treatment and control groups. Treated children had a larger height gain (FH PAH0) than controls: 4.4 (4.9) and 0.5 (6.4) cm, respectively (P < 0.05). FH was higher than PAH0 in 76 and 60% of treated and control subjects, respectively. During follow-up, 50% of the predicted height gain at treatment withdrawal was lost, resulting in a mean gain of 4.9 cm (range, 4.0 to 12.3 cm) compared with controls. Treatment did not affect body mass index or hip bone mineral density. Mean lumbar spine bone mineral density and bone mineral apparent density tended to be lower in treated boys, albeit statistically not significant.
Conclusion: Given the expensive and intensive treatment regimen, its modest height gain results, and the possible adverse effect on peak bone mineralization in males, GH plus GnRHa cannot be considered routine treatment for children with idiopathic short stature or persistent short stature after being born small for gestational age.
| Introduction |
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An alternative for GH treatment is to delay or halt pubertal onset with GnRH agonists (GnRHa). However, in many children, GnRHa therapy concomitantly decreases growth velocity to values below the normal prepubertal pace, which may at least in part result from accelerated growth plate senescence induced by previous estrogen exposure (7).
Combined GH and GnRHa treatment in adolescents with short stature has been analyzed in a few studies with limited numbers of patients and conflicting results. None of these were randomized controlled trials (RCT), and FH results are scarce. Height gain defined as the difference between FH and baseline predicted adult height (PAH0) was 1.010.0 cm (8, 9, 10, 11, 12, 13). Treatment response was usually analyzed by comparison with a GH-treated group (12, 14) or a not randomly assigned, untreated control group (9, 15) or no control group at all (8). Moreover, most of the trials focused on girls only and excluded children with a persistent short stature after being born SGA.
In 2001, we reported 3-yr results of the first RCT investigating GH plus GnRHa (GH + GnRHa) treatment in short, early pubertal adolescents with ISS or SGA. We concluded that 3 yr of GnRHa treatment was effective in suppressing puberty, whereas growth velocity was preserved due to addition of GH, resulting in a significant gain in PAH without demonstrable side effects (16). Assessment of the motives of adolescents and their parents to participate in this trial and psychosocial functioning of the participants during treatment were described recently (17, 18). Psychosocial functioning in young adulthood will be described elsewhere (Visser-van Balen, H., submitted for publication). Here we report FH data and analyze possible adverse effects of treatment on bone mineral density (BMD), bone mineral apparent density (BMAD), and body mass index (BMI).
| Patients and Methods |
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This report includes FH results from 32 of 40 adolescents with short stature that originally enrolled in a multicenter study in The Netherlands in 19931996. Inclusion criteria were chronological age (CA) and bone age (BA) less than 12 yr (girls) or less than 13 yr (boys); pubertal stage of G23 (boys) or B23 (girls); height at baseline (H0) less than 2.0 SDS for Dutch references (19) or between 1.0 and 2.0 SD score (SDS) with PAH0 less than 2.0 SDS, according to Bayley and Pinneau, (20); maximum serum GH level more than10 µg/liter (1 mg = 2 IU, using World Health Organization (WHO) International Reference Preparation 66/217 as standard) after provocation (exercise, arginine, clonidine, L-dopa, or glucagon), and a normal sitting height/subischial leg length ratio (between P3 and P97) (21). Screening blood tests and urinalysis were normal. No organic cause of growth failure, primary bone disease, chronic illness, or dysmorphic syndrome was present. During the trial phase, fasting glucose and insulin levels remained within the normal range in all children. Markers for bone formation (osteocalcin, alkaline phosphatase, procollagen type IC propeptide, and procollagen type III N propeptide) were not different between treatment and control groups. Details of the subjects and data obtained after withdrawal of treatment were reported previously (16).
The protocol was approved by medical ethical review boards at the four participating centers (Amsterdam, Utrecht, Eindhoven, and Rotterdam). Before conducting any study-related procedure, written informed consent was obtained from parents and, when appropriate, also from the participants. This clinical trial was registered in the metaRegister of Controlled Trials (ISRCTN82161629) of the Current Controlled Trials Ltd.
Study design
Forty patients were randomly allocated to receive combined treatment with GH + GnRHa or no treatment for a period of 3 yr (Fig. 1
). GH (Genotropin; Pharmacia, Uppsala, Sweden; now Pfizer, New York, NY) was given in a dose of 1.33 mg (4 IU)/m2·d sc, equivalent to 0.05 mg/kg body weight·day. A 3.75-mg 1-month depot preparation of GnRHa was administered im [triptorelin (Decapeptyl) Ferring, Malmö, Sweden; after withdrawal by Ferring in 1998, triptorelin from Ipsen, Paris, France, was used]. This corresponded to a mean triptorelin dose of 125 µg/kg at start of treatment and 67 µg/kg at discontinuation of treatment.
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Adolescents were considered to have attained FH if treatment withdrawal was at least 3 yr before evaluation and CA was greater than or equal to 18 yr (girls) or 19 yr (boys). FH, being the average of four measurements made by a single observer using a Harpenden stadiometer, was determined at an outpatient clinic visit or at a house visit.
BMD
BMD of the lumbar vertebrae and hip were measured by dual-energy x-ray absorptiometry (DXA) at the moment of FH analysis. DXA scans were performed at the Department of Radiology of the VU University Medical Center in Amsterdam or at the Diagnostic Center Eindhoven using a Hologic Delphi 4500A or a Hologic Delphi W-type 70991 (Hologic, Waltham, MA), respectively. Cross-calibration with phantoms demonstrated that the DXA machines were comparable, and data from both centers were pooled. Each machine was calibrated using the manufacturers daily quality control protocol. Z-scores were calculated, using hip reference values based on the National Health and Nutrition Examination Survey from 19881991 (NHANES) (23) and Hologic reference values for lumbar spine (L1L4). To correct for bone size, DXA-derived data were used to calculate lumbar spine BMAD (24). BMAD Z-scores could not be calculated due to the lack of appropriate reference values.
Outcome parameters
Four outcome parameters were used to evaluate response to treatment: 1) FH (SDS); 2) FH minus baseline height (H0) (SDS); 3) FH minus PAH0 (cm) according to Bayley and Pinneau (20); and 4) FH minus target height (TH) (cm). FH minus PAH3 (PAH at discontinuation of treatment) was also calculated, to show the difference between final outcome and height prediction at discontinuation of treatment. All SDS were based on Dutch references (19). For calculation of FH SDS, the age of each patient was set at 21 yr, enabling comparison of FH with height distribution in the normal adult population. For three patients, a BA radiograph at baseline was not available, and BA determination closest to this time point was used and transformed to BAbaseline as follows: BAbaseline = (BAvisit/CAvisit) x agebaseline. TH was calculated as midparental height plus or minus 6 cm (for boys and girls, respectively), plus 3 cm to correct for the average secular trend in The Netherlands (25). One patients TH could not be calculated, because of adoption from a foreign country and absence of height data of his biological parents.
The following outcome parameters were used to analyze possible effects of GH + GnRHa treatment on bone mineralization and body weight: 1) lumbar spine BMD (SDS) and BMAD (g/cm3); 2) hip BMD (SDS); and 3) BMI (SDS).
Statistical analysis
The study was designed to compare the effects of GH + GnRHa treatment with those of no treatment on FH. Statistical analyses were performed using the statistical package SPSS, version 11.0.1 (SPSS, Chicago, IL). Results are expressed as mean (SD). Comparisons among treatment and control groups were made using Students unpaired t tests. Possible interactions between GH + GnRHa treatment and the baseline predictors gender, diagnostic subgroup, age at baseline (age0), height at baseline (H0SDS), and BA delay (CA BA) were analyzed by means of linear regression analysis using ANOVA. The significance level was set at 0.05.
| Results |
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There was a significant gain in PAH of 9.3 cm after 3 yr of GH + GnRHa treatment, compared with 1.2 cm gain in the control group (Fig. 2
). There was no significantly different pattern between the two diagnostic subgroups and genders in changes in height parameters.
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Patient characteristics at start, after treatment discontinuation, and at the moment of FH analysis are listed in Table 1
. FH data were collected at a mean age of 19.9 (1.8) and 20.9 (1.0) yr in girls and boys, respectively. The mean treatment period was 3.0 yr (range, 2.83.3 yr). The mean period elapsed between treatment discontinuation and final analysis was 5.7 yr (range, 3.68.7 yr).
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Height gain (FH PAH0) was 4.4 (4.9) in the treatment and 0.5 (6.4) cm in the control group (Fig. 2B
). Of the predicted 9.3 cm gain in PAH (PAH3 PAH0), approximately 50% was lost during follow-up (Fig. 2
), resulting in a net gain of 4.9 cm in the treatment group, compared with controls. Seventy-six percent of the GH + GnRHa-treated children and 60% of the controls had a FH greater than predicted at baseline.
Height gain was similar in both genders, but there was a difference in the accuracy of the height prediction method between genders. Untreated boys attained a FH 5.5 (4.1) cm lower than predicted at baseline, whereas untreated girls became 1.9 (6.0) cm taller. Treated girls had a FH significantly closer to TH than controls (P < 0.05), whereas no significant difference existed between treated and untreated boys.
Linear regression analysis of predictors for growth response
Gender was a predictor for the treatment effect [(GH + GnRHa) x gender] expressed in FH TH, with girls showing a better response than boys [regression coefficient B = 10.7; confidence interval (CI) = 1.320.2; P < 0.05; graph not shown]. Age at baseline showed a trend toward a positive interaction with treatment effect [(GH + GnRHa) x age0] in the outcome parameters FH SDS H0SDS (B = 0.7; CI = 0.011.5; P < 0.1), and FH SDS PAH0 SDS (B = 0.8; CI = 0.11.7; P < 0.1). Baseline height and diagnostic subgroup were not significant predictors for treatment effect in any of the outcome parameters.
Side effects
Lumbar spine and hip BMD were determined in 21 patients (69%), 15 treated and six control subjects; the others could not be motivated. There was no apparent difference in lumbar spine and hip BMD SDS between treated and untreated children (Fig. 3
, A and C). Lumbar spine BMD SDS was markedly lower in the six treated boys [2.5 (1.0) SDS] than in the two controls [1.1 (0.3) SDS] who consented to undergo this diagnostic procedure (P = 0.1; CI = 0.53.3). This difference was statistically not significant due to the small sample size of the control group (n = 2). Lumbar spine BMAD showed a similar, albeit less prominent pattern (Fig. 3B
). BMI SDS remained unchanged during and after GH + GnRHa treatment in boys and girls.
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| Discussion |
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Two previously published studies employed untreated controls as reference group. Saggese et al. (26) found an increase in PAH of 6.1 cm after 2 yr of GH + GnRHa in seven ISS girls compared with controls. In contrast, Lanes and Gunczler (9) found no improvement in PAH or FH after 2.5 yr of treatment in 10 short boys and girls. Other studies with different experimental designs showed similarly contrasting results on growth, varying from no effect on FH or PAH gain in girls with familial short stature (8) and in ISS boys and girls (14) to 10.5 cm gain in PAH and 10 cm height gain (FH PAH0) in ISS girls (12). These studies and ours cannot easily be compared because of differences in experimental design. GH + GnRHa trials in short adopted girls showed an increased PAH, FH PAH0, and FH compared with GnRHa-treated controls (10, 13). Mul et al. (10) suggested that the relevance of their results in adopted girls might be extrapolated to girls born SGA and those with ISS. Indeed, in our trial, we found significantly increased PAH, height gain, and FH compared with TH in the treated girls.
Approximately 50% of the apparent gain in PAH during treatment was lost during follow-up. Initial height prediction overestimated FH in untreated boys, which has also been described by others (27). Height gain in terms of FH PAH0 is similar in both genders, although the accuracy of height prediction depends on gender. Untreated boys attain a FH considerably lower than predicted at baseline, whereas girls become slightly taller. Prediction at discontinuation of treatment overestimated FH, regardless of gender. A longer duration of combined therapy might further increase height gain but would delay puberty even longer up to an age that would far exceed the normal range. This might cause adverse effects on psychological and bone parameters. However, prolonging GH treatment after discontinuation of combined treatment until FH may be a way to fulfill part of the height gain predicted in PAH3.
Gender did not influence the response to GH + GnRHa in three of four outcome parameters. Only for FH TH was a better response to treatment seen in girls. Previously published studies on GH + GnRHa treatment were usually conducted in short girls only, except a few small trials including both genders (9, 14). The inclusion of boys in our trial might explain a somewhat lower overall response to treatment compared with other studies on GH + GnRHa treatment in short girls. The predictive value of gender on height outcome is limited in this study, because an effect was found in only one outcome measure (FH TH).
We included an SGA subgroup, even though this category of patients was excluded from the 1996 consensus definition of ISS (28) and from most of the previously published studies. In our opinion, the distinction between ISS and idiopathic SGA is arbitrary because of varying definitions and reference values for length and weight for gestational age. In the ISS consensus, SGA was defined as a birth weight and/or length less than 2.0 SDS for gestational age. This definition implies that a child with a birth weight in the lower normal range may be categorized as ISS in case of an unknown birth length and as SGA if birth length would be recorded as less than 2.0 SDS. Moreover, the Gaussian distribution of birth weight and length in ISS is shifted to the left by 1 SDS (29), suggesting that persistent short stature born SGA and ISS are not separate entities. SGA and ISS children in our study had a similar response to treatment, demonstrating that diagnostic subgroup did not interact with the treatment effect. Similarly, Crowe et al. (30) found no difference in response to GH treatment between SGA or ISS groups. However, patient numbers in our subgroups were small, and larger sample numbers are required to analyze responses to definitely confirm or reject our hypothesis that SGA and ISS children respond similarly to combined GH + GnRHa treatment.
Apart from beneficial effects on height gain, GH + GnRHa treatment may also have adverse effects. Palmert et al. (31) found an elevated BMI in GnRHa-treated girls with central precocious puberty. We did not find an increased BMI, either directly after discontinuation of treatment (16) or at FH analysis. The stimulatory effect of GnRHa on fat mass induction may have been counterbalanced by an adverse effect of GH in the treated children. The elevated BMI in GnRHa-treated girls from the American trial was possibly associated with precocious puberty itself rather than with the treatment.
Another relevant possible side effect of GnRHa treatment was described by Yanovski et al. (32), who found a significantly decreased lumbar spine BMD after 4 yr of GnRHa treatment, with or without GH, of children with short stature based on various etiologies. A similar result was reported after 3.4 yr of GnRHa treatment in girls with ISS (33). In GnRHa-treated children with central precocious puberty, lumbar spine BMD was significantly decreased during treatment (34) but restored to normal values several years after withdrawal of treatment (33, 34), suggesting that GnRHa therapy did not impair peak bone mass in this subcategory of patients. In contrast, Finkelstein et al. (35) demonstrated that adult men with a history of delayed puberty had a decreased radial and spinal BMD, suggesting that the timing of puberty is an important determinant of peak bone density in men. BMD achieved during young adulthood might be a major determinant of bone density and a predictor for the risk of osteoporotic fractures in later life.
In our study, there was no apparent difference between treatment and control groups in lumbar spine and hip BMD measured at least 3.5 yr after termination of treatment. However, the six treated boys had a lower lumbar spine BMD and BMAD than the two untreated boys, albeit statistically not significant. A meta-analysis by Marshall et al. (36) demonstrated that with each 1 SDS decrease in lumbar spine BMD, fracture risk increased 2.3-fold. Therefore, we believe that there is sufficient reason to be cautious when considering GH + GnRHa treatment in boys. On the other hand, it has been shown that after interruption of skeletal development in childhood, there is still potential for catch-up in BMD, even going into the third decade of life (37, 38). Taking this into account, it remains to be seen whether the low lumbar spine BMD in treated boys has clinical repercussions and whether it will restore to normal values.
In girls, there was no difference in lumbar spine and hip BMD between treated and control groups. This may be explained by an immediate rise in estrogen to high levels after treatment withdrawal in girls, favoring bone mineralization. In boys, the posttreatment rise in estrogen levels may be slower and reach a lower maximum, resulting in a later and possibly lesser stimulation of bone mineralization.
Apart from these clinical issues, psychosocial issues should also be taken into account. Analyses of psychosocial functioning during treatment tentatively suggested adverse psychological consequences for the treated adolescents on self-perceived competence of scholastic and athletic ability and trait anxiety (17). Parents reported some behavioral problems in their children before treatment (18) but did not report changes during treatment. Psychosocial outcome after attaining final adult height was one of the final evaluation criteria of this trial, and so far no differences have been observed between treatment and control groups in social circumstances, height-related psychosocial stressors, perceived competence, and psychological distress in young adulthood (Visser-van Balen, H., submitted for publication).
We conclude that 3 yr of GH + GnRHa treatment has a positive but modest effect of 4.9 cm on final height in short, early pubertal children with ISS or a persistent short stature born SGA, compared with untreated controls. The costs of long-term treatment with GH + GnRHa of short but otherwise healthy patients with extremely expensive drugs that require parenteral administration and regular clinic visits and may have an adverse effect on peak bone mineralization, particularly in males, overshadows the modest benefit of 4.9 cm height gain. We therefore do not recommend this treatment regimen in general. However, treatment may be felt justified in individual patients, particularly girls, with an extremely low adult height prediction, an early pubertal onset, and considerable psychosocial problems.
| Acknowledgments |
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| Footnotes |
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Part of this work was presented as a poster at the 7th Joint Meeting of European Society for Paediatric Endocrinology/Lawson Wilkins Pediatric Endocrine Society, Lyon, France, September 2005.
Author Disclosure Summary: S.A.v.G., G.A.K., H.V.-v.B., D.M., J.J.J.W., M.J., L.V.-W., H.A.D.-v.d.W., G.L., and J.C.R. have nothing to declare. S.M.P.F.d.M.K.-S. has been paid lecture fees by Novo Nordisk and Pfizer. J.M.W. has received consulting fees and lecture fees from Pfizer, Lilly, and Ipsen.
First Published Online February 6, 2007
Abbreviations: BA, Bone age; BMAD, bone mineral apparent density; BMD, bone mineral density; BMI, body mass index; CA, chronological age; CI, confidence interval; DXA, dual-energy x-ray absorptiometry; FH, final height; GnRHa, GnRH agonist; ISS, idiopathic short stature; PAH0/3, predicted adult height at baseline/at discontinuation of treatment; RCT, randomized controlled clinical trial; SDS, SD score; SGA, small for gestational age; TH, target height.
Received October 17, 2006.
Accepted January 29, 2007.
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