Endocrine Abstracts

A recently published meta-analysis has demonstrated a significant beneficial effect on exercise performance of growth hormone (GH) replacement in GH-deficient (GHD) adults. The current meta-analysis was carried out to determine whether GH replacement confers a similar improvement in muscle strength in this patient group. A medline search and examination of reference lists of included studies and relevant review articles identified five studies with utilizable, robust data, involving a total of 268 patients in six patient cohorts. All of the included studies were randomized, double-blind, placebo-controlled, and of either parallel or cross-over design. All studies were of six to twelve months duration. Information was retrieved in uniform format, with data pertaining to patient numbers, study design, GH dose, mean age, IGF-I levels, and muscle strength measurements (isometric or isokinetic quadriceps strength) recorded. The data was analyzed using a fixed effects model, utilizing continuous data measured on different scales. A summary effect measure (d_s) was derived for the individual exercise parameters, while an overall summary effect was derived from the sum of all studies incorporating different variables; 95% confidence intervals were calculated from the weighted variances of individual study effects. Results revealed no statistically significant improvement for either measure individually (isometric quadriceps strength, d_s=+0.11±0.42 (n=131) and isokinetic quadriceps strength, d_s =+0.11±1.05 (n=49)), or when all studies were combined (d_s =+0.11±0.39 (n=180)). This study shows that there is a lack of high-quality evidence to support a benefit on muscle strength of GH replacement in GHD patients. This is in spite of recent evidence of improved exercise capacity in such patients. This should be considered when GH replacement is being discussed with, and prescribed for, patients with GH deficiency.