IGF-1: a potential biomarker for efficacy of sleep improvement with automatic airway pressure therapy for obstructive sleep apnea?

Background: Positive airway pressure (PAP) reverses obstructive sleep apnea (OSA)-related hypoxia and restores slow wave sleep (SWS). Insulin-like growth factor 1 (IGF-1) is a neuropeptide that facilitates the repair of neurons from hypoxia and improves sleep regulation. IGF-1 concentrations are lower in OSA, and likely increase following PAP treatment; however, this relationship has not yet been determined in a younger cohort of OSA patients. Methods: This was a prospective, observational pilot study of 58 young men, who were diagnosed with OSA and provided PAP as an intervention. Adherence to PAP treatment over 3 months was objectively measured, as well as changes in the apnea–hypopnea index (AHI). Serum concentrations of IGF-1and C-reactive protein (CRP) were measured and correlated with PAP adherence. Results: IGF-1 concentrations at baseline were similar between PAP adherent 55.5 ± 34.4 ng/ml and PAP nonadherent participants 61.2 ± 27.1 ng/ml (p = 0.4), with the overall mean IGF-1 concentration of 59.0 ± 29.9 ng/ml. At follow-up, adherent participants had concentrations of IGF-1 that were significantly higher 128 ± 59.5 ng/ml compared to nonadherent participants 86.0 ± 47.4 ng/ml (p < 0.01). Increases in IGF-1 concentrations were significantly associated with reductions in AHI (Spearman’s rho = −0.409, p = 0.015). Conversely, CRP concentrations did not differ between baseline and follow-up measurements in either group. Conclusions: Adherence to PAP treatment leads to significant increases in IGF-1 concentrations in young men with OSA. While an objective measure of adherence exists, PAP usage does not allow for measure of sleep improvement. IGF-1 may serve as a potential biomarker for the efficacy of PAP therapy on improved sleep.