Background Country-specific data on outcomes of treatment with recombinant human growth hormone are lacking. We present such data for children treated with growth hormone in Canada. Methods We describe characteristics and outcomes of 850 children (mean age at baseline 8.5 yr) treated with growth hormone constituting the Canadian cohort of the multinational phase IV prospective observational Genetics and Neuroendocrinology of Short-stature International Study (GeNeSIS). The diagnosis associated with short stature was as determined by the investigator. Auxological data were evaluated yearly until near-adult height. Adverse events were assessed in all growth-hormone-treated patients. Results The diagnosis ascribed as the cause of short stature was growth hormone deficiency in 526 children (61.9%), predominantly organic rather than idiopathic, particularly congenital pituitary abnormalities and intracranial tumours. All diagnostic groups with sufficient patients for analysis had increased height velocity standard deviation score (SDS) and height SDS during growth hormone treatment. For patients who reached near-adult height (n = 293), the mean height SDS was within the normal range for about 80% of patients with organic growth hormone deficiency (n = 131) or idiopathic growth hormone deficiency (n = 50), 50% of patients with idiopathic short stature (n = 10) and 46% of patients with Turner syndrome (n = 79). Eleven deaths were reported, 7 in patients with organic growth hormone deficiency. Serious adverse events considered related to growth hormone treatment (n = 19) were isolated except for medulloblastoma recurrence (n = 2) and adenoidal hypertrophy (n = 2). Interpretation Growth hormone treatment was effective and had a good safety profile in Canadian children. Growth hormone dosages were lower than in the US and global GeNeSIS cohorts, and a greater proportion of treated Canadian children had organic growth hormone deficiency. Study registration ClinicalTrials.gov, no. NCT01088412.
