Eighteen RCTs (n=508) were included in the review.
No study met all of the quality criteria. The numbers of quality criteria fulfilled ranged from 3 to 7 out of 8. Study sizes were small (mean 28 participants) and some had high drop-out rates.
The funnel plots did not suggest the presence of publication bias.
Efficacy.
There was no statistically significant difference in weight loss between participants who did and did not receive GH. Participants who received GH showed a significant reduction in fat mass (-2.08 kg, 95% confidence interval, CI: -2.80, -1.35) and increase in lean body mass (2.13 kg, 95% CI: 1.32, 2.94) relative to participants not receiving GH.
There was no significant difference in body composition outcomes between participants receiving GH with and without a lifestyle intervention. Based on one study, participants treated with GH alone showed a significant 2.2-kg reduction in lean body mass compared with participants who received exercise therapy alone. However, the decrease in fat mass did not differ between the groups.
There were no significant differences in body composition outcomes between studies that administered GH for 26 weeks and those that administered it for less than 26 weeks. When only those studies administering GH therapy for at least 12 or 26 weeks were analysed, the results did not change. Women treated with GH showed no significant increase in lean body mass, but a borderline statistically significant decrease in fat mass, compared with women not treated with GH. Men treated with GH showed significant improvements in body mass and fat mass.
There was no statistically significant difference in total cholesterol levels between groups after adjustment for decrease in fat mass. There were no statistically significant differences between treatment groups for any other outcomes.
The included studies for measures of weight and fat mass showed little heterogeneity, whereas those for lean body mass did show heterogeneity (I-squared 41%). Heterogeneity for this outcome was particularly high for studies that evaluated women, provided GH alone without lifestyle intervention, or provided GH therapy for 26 weeks or more. The I-squared statistic was greater than 50% for femoral neck bone density and for triglyceride, fasting glucose and fasting insulin levels.
Safety.
Participants receiving GH had significantly higher rates of adverse events (including soft tissue oedema, carpal tunnel syndrome, arthralgias and gynaecomastia) than those not receiving GH. Women receiving GH were more likely to experience oedema than men receiving GH. Higher rates of glucose metabolism-related adverse events were reported in participants receiving GH compared with those not receiving GH, but this finding was not statistically significant.
Results of the sensitivity analyses were also reported.