Quality of life, body composition and muscle strength in adult growth hormone deficiency: the influence of growth hormone replacement therapy for up to 3 years.

Abstract

Adults with GH deficiency complain frequently of low energy levels, emotional lability and mental fatigue resulting in a low perceived quality of life (QOL). Body composition is altered with increased fat mass and decreased lean body mass and muscle strength is reduced. The aims of this study were to determine the effects of replacement GH treatment on: (a) body composition and muscle strength and (b) QOL, using specifically selected and adapted measures. A 12-month study (double-blind placebo-controlled for the first 6 months and open for the second 6 months) of GH replacement injections (0.125 iu/kg/week for the first month and 0.25 iu/kg/week for the following 5 months of each study period) in GH deficient adults on QOL, body composition and muscle strength. This was followed by an open study of a further 12 months' GH treatment assessing QOL and muscle strength. Finally, QOL was assessed after up to 3 years of GH replacement treatment. Thirty of the 32 adult patients with GH deficiency enrolled completed the initial 12-month study (10 male, mean age 33.5 years, mean (SD) stimulated serum GH response 3.0 mU/l (2.86)). Nineteen patients then opted to continue GH treatment. Of these, 13 patients were available for assessment after a further 12 months' and 24 months' treatment. Health-related QOL was assessed using 2 specifically adapted scales for adults with GH deficiency: the Life Fulfillment Scale and the Impact Scale. In addition 4 other self-rating questionnaires were used: Nottingham Health Profile, Hospital Anxiety and Depression Scale, Self Esteem Scale and Mental Fatigue Scale. Body composition was assessed by DEXA and quadriceps muscle strength by measuring maximum voluntary contractions. In the initial 12 months' placebo-controlled study perceived energy levels increased after 6 and 12 months of GH treatment (P < 0.01 compared with baseline) in the patients receiving GH for the full 12-month period. There were no changes in energy levels throughout the study in the group receiving placebo for the first 6 months. Also small improvements in impact scores were found after 6 months of GH treatment (P < 0.05) but this was not sustained at 12 months. In both GH and placebo groups life fulfillment worsened after 6 months, but then improved to baseline values after 12 months. In the patients who persisted with GH replacement, energy levels continued to improve (at 2 years, P < 0.01 compared with baseline) but then fell (at 3 years, P = NS compared with baseline). A similar pattern was observed in emotional reaction scores. However, improvements in self-esteem were maintained (at 3 years, P < 0.05 compared with baseline). Body composition altered favourably over the initial 12-month study period with a significant increase in lean mass and decrease in fat mass in both groups after 6-12 months of GH. There were no changes in muscle strength in either group during the initial 12-month study. However, in the patients who were available for assessment after a further 12 months of GH treatment, muscle strength increased significantly (P < 0.02 compared with baseline). GH replacement treatment for 6-12 months leads to significant improvements in body composition (DEXA) but longer-term treatment may be needed to increase muscle strength. Self-esteem scores improve and are maintained after 3 years of treatment. Energy levels and emotional reaction improve during treatment for up to 2 years but decline thereafter.