Background: Growth hormone deficiency (GHD) is an increasingly recognized potential consequence following traumatic brain injury (TBI). Outside of a formal, blinded RCT to demonstrate treatment effects, long term adherence to hGH replacement in a full reimbursement setting may serve as a pragmatic indicator of patient-perceived therapy benefits. Our objective was to evaluate adherence to therapy at one year for patients with GHD secondary to TBI in a full reimbursement setting.
Methods: We conducted a retrospective chart review of patients evaluated for GHD at the TBI clinic (>1 year post TBI) and referred to endocrinology for GH stimulation testing with insulin tolerance test (ITT) or glucagon stimulation test (GST) since December 2013. We obtained patient demographics, severity of TBI, baseline and post therapy IGF-1 level, data pertaining to pituitary hormone deficiencies, result of GH stimulation testing, and adherence to GH at one year follow-up from GH initiation. Adherence to therapy was defined according to the presence or absence of patient-initiated clinic follow up visits, a requisite step for ongoing hGH prescriptions.
Results: 64 patient charts were reviewed. 48 patients had mild TBI, 6 had moderate TBI, 8 had severe TBI, and 2 patients had a non-traumatic etiology of brain injury. 42 patients underwent ITT or GST, and 27 patients were confirmed to have GHD. At the time of analysis, 20 patients had been started on GH therapy 1 year ago or longer. Of these patients, 11/20 returned for follow-up to continue GH replacement beyond one year, while 9/20 did not return for GH renewal beyond three months.
Discussion: In a full reimbursement setting, adherence to hGH replacement therapy at one year is modest, suggesting that GH replacement may not provide significant symptomatic benefit in many patients with GHD from traumatic brain injury.