Control of growth hormone and IGF1 in patients with acromegaly in the UK: responses to medical treatment with somatostatin analogues and dopamine agonists.

OBJECTIVE: We investigated the control of GH and IGF1 in acromegaly in routine clinical practice in the UK on and off medical treatment.
DESIGN: The UK Acromegaly Register collected routine biochemical and clinical data on patients with acromegaly from 31 UK centres with GH data covering >30y. PATIENTS: We identified 2572 patients. Somatostatin analogues (SMS) were used in 40·6% and dopamine agonists (DA) in 41·4%. MEASUREMENTS: We identified 29,181 GH records linked to data on IGF1, surgery, radiotherapy and medical treatment and derived data on 9900 distinct Periods of Care including 4206 courses of medical treatment. We considered GH controlled when ≤2 μg/l.
RESULTS: Control of GH and IGF1 improved over time, particularly on medical treatment. Control on medical treatment was better after prior surgery and/or radiotherapy. On long-term SMS, GH was controlled in 75%, IGF1 in 69% and both in 55%; on long-term DA, GH control was similar but IGF1 worse (77%/55%/45%). Responses to long-term treatment with octreotide LAR and lanreotide autogel were broadly similar, but we noted a failure to escalate SMS to maximal effective dose. Increasing precourse GH levels were associated with a decreasing proportion who achieved control, despite greater suppression from baseline.
CONCLUSIONS: Control of acromegaly in the UK is improving, but 'safe' GH levels are still only achieved in 75% on long-term medical treatment, with GH and IGF1 both normalized in no more than 55% on SMS and 36% on cabergoline. It remains unclear whether the control of GH, but not IGF1, observed in many patients is sufficient to restore long-term morbidity and mortality to normal.