Insulin like growth factor-I in acute subarachnoid hemorrhage: a prospective cohort study

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Abstract
Introduction: Neuroendocrine deficiencies may affect recovery after aneurysmal subarachnoid hemorrhage (aSAH). Insulin like growth factor-I (IGF-I) regulates neuronal growth and apoptosis in ischemic stroke. Our study was designed to a) characterize the behavior of serum IGF-I and growth hormone (GH) in the acute and late phases after aSAH reflecting possible pituitary gland function and b) evaluate the association between IGF-I and morbidity assessed by Glasgow outcome scale (GOS) and health related quality of life (HRQoL) in patients with aSAH. Methods: In this prospective cohort study, patients with aSAH (n = 30) were compared to patients who underwent elective aneurysm surgery (n = 16). Serum GH and IGF-I concentrations were measured daily for five (controls) or seven (aSAH) days and at three months. GOS and 15d HRQoL was measured at three months. A mixed models method was used for testing between the groups. For factors possibly affecting HRQoL in aSAH patients, we constructed a Bayesian predicting model using a P-course Bayesian classifier. Results: The mean IGF-I concentrations for days one to five were 8.1 ± 3.5 nmol/l in patients with aSAH and 11.2 ± 3.1 in the control group (P = 0.01). No corresponding difference was found at three months. Serum GH concentrations were similar in both patient groups. Severity of the aSAH did not affect serum IGF-I concentrations. Patients with GOS ≤ 4 had lower IGF-I concentrations and lower HRQoL than patients with GOS 5 (P = 0.02 and 0.003 respectively). The 15d HRQoL was 0.81 ± 0.16 in patients with aSAH and 0.86 ± 0.09 in control patients (P = 0.24). In the Bayesian model, the use of statins prior to aSAH, hyponatremia, high maximal sequential organ specific score (SOFAmax), and low cumulative IGF-I concentrations on days one to seven were associated with poor HRQoL (accuracy 89%, sensitivity 86%, and specificity 93%). Conclusions: IGF-I concentrations are low during acute aSAH, which may have an impact on morbidity. Trial registration: ClinicalTrials.gov Identifier NCT00614887