Factors influencing the desire for long-term growth hormone replacement in adults

Growth hormone replacement in adults may be considered beneficial by clinicians, but patients may not perceive any benefits. The purpose of this study was to determine whether there were any factors which influenced whether an adult wished to continue on long-term GH replacement after taking part in a study of GH replacement.

A 12-month study (double-blind placebo controlled for the first 6 months and open for the second 6 months) of GH replacement (0.125 IU/kg/week for the first month and 0.25 IU/kg/week thereafter) in adults.

Sixty-three adults (27 men, 36 women, aged 34.9 +/- 1.4 (mean +/- SE, range 20.1-59.5) years) with GH deficiency (peak serum GH response to provocative testing less than 10 mU/l) who entered a 12-month study of GH replacement. Thirty patients (48%) wished to continue on GH replacement and 33 patients (52%) did not wish to continue on GH replacement after the study.

Biochemical, anthropometric and demographic characteristics, and well-being, were compared in those patients who wished to continue on long-term GH replacement and in those who did not. In the two groups of patients the age, height, weight, body mass index, serum insulin-like growth factor (IGF)-I, IGF binding protein (IGFBP)-3 and IGF-I age matched standard deviation score (SDS) were compared at entry into the study, and changes in IGF-I, IGFBP-3 and IGF-I SDS were compared after 6 months of GH replacement. The patients were compared according to pretreatment peak serum GH response to provocative testing, sex, estimated duration of GH deficiency, whether GH deficiency was of childhood or adult onset, presence or absence of additional pituitary hormone deficiencies, underlying pathological disorder, previous therapeutic interventions, employment status, marital status and living arrangement, and according to development of side-effects of GH replacement and the requirement for reduction in dose of GH because of side-effects during the study. Scores on two questionnaire measures of well-being or distress, the Nottingham Health Profile (NHP) and the Psychological General Well-Being Schedule (PGWBS), were compared at entry into the study in the two groups, as were change in scores on these questionnaires after 6 months of GH replacement.

Those who continued on GH replacement tended to have a greater severity of GH deficiency (median peak serum GH concentration 0.7 vs 2.3 mU/l, P = 0.06), tended to have greater distress in terms of energy (NHP, P = 0.06) and vitality (PGWBS, P = 0.06) at entry into the study and showed an improvement in energy during the study compared with no change in those who did not wish to continue on GH replacement (NHP, P = 0.06).

Those adults who wished to continue on GH replacement tended to have a greater severity of GH deficiency, to experience more distress in terms of energy and vitality at entry into the study and to experience an improvement in energy after 6 months treatment with GH.