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Characteristics of children with the best and poorest first- and second-year growth during rhGH therapy: data from 25 years of the Genentech national cooperative growth study (NCGS)

Paul B Kaplowitz1*, Dorothy I Shulman2, James W Frane3, Joan Jacobs4 and Barbara Lippe5

Author Affiliations

1 Endocrinology, Children’s National Medical Center, George Washington University School of Medicine & Health Sciences, Washington, DC, USA

2 Pediatric Endocrinology, All Children's Hospital, All Children's Hospital, St. Petersburg, and University of South Florida, Tampa, FL, USA

3 Biostatistics, Santa Monica, CA, USA

4 Biostatistics, Genentech, Inc., South San Francisco, CA, USA

5 Genentech, Inc., South San Francisco, CA, USA

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International Journal of Pediatric Endocrinology 2013, 2013:9  doi:10.1186/1687-9856-2013-9

Published: 1 May 2013

Abstract

Background

Models assessing characteristics contributing to response to recombinant human growth hormone (rhGH) response rarely address growth extremes in both years 1 and 2 or examine how children track from year to year. Using National Cooperative Growth Study (NCGS) data, we determined characteristics contributing to responsiveness to rhGH and the pattern of change from years 1 to 2.

Patients and methods

Height velocity standard deviation score (HV SDS) for 2 years for prepubertal children with idiopathic GH deficiency (IGHD) (n = 1899) and idiopathic short stature (ISS) (n = 1186) treated with similar doses for two years were computed. Group 1 = HV SDS < −1; 2 = HV SDS −1 to +1; 3 = HV SDS > +1.

Results

For IGHD, mean age was 7.5 years and similar in all groups. Year 1 HV SDS was associated with greater body mass index (BMI) SDS, lower pre-treatment HV, baseline height SDS, greater target height SDS minus height SDS, and lower maximum stimulated GH (P <0.0001). Year 2, 172/271 (73%) in group 1 moved to either group 2 (n = 156) or 3 (n = 16). Year 2 HV SDS was associated with greater year 1 HV SDS (r = 0.045, P <0.0001), greater BMI SDS, taller parents and lower peak GH.

For ISS, year 1 HV SDS was associated with greater BMI SDS and lower pre-treatment HV (P ≤0.0001). 109/169 (64%) in group 1 moved to group 2 (n = 90) or group 3 (n = 19). Greater year 2 HV SDS was related to year 1 HV SDS (r = 0.27, P <0.0001).

Conclusion

For IGHD, multiple characteristics contributed to best first-year response but for ISS, best first-year HV SDS was associated only with BMI SDS and inversely with pre-treatment HV. For both GHD and ISS, year 1 HV SDS was not a strong enough predictor of year 2 HV SDS to use first-year HV alone to determine GH continuation.

Keywords:
Growth hormone deficiency; Idiopathic short stature; Growth hormone therapy