Effect of continuous positive airway pressure on insulin growth factor-1 in patients with obstructive sleep apnea: A meta-analysis

Objective: Obstructive sleep apnea (OSA) has been recognized as being associated with low level of insulin growth factor-1 (IGF-1). However, the impact of OSA treatment using continuous positive airway pressure (CPAP) on IGF-1 remains controversial. We performed a meta-analysis to determine whether effective CPAP therapy could increase IGF-1 levels. Design: Two reviewers independently searched PubMed, Cochrane library, Embase and Web of Science before September 2014. Information on characteristics of subjects, study design and pre- and post-CPAP treatment of serum IGF-1 was extracted for analysis. Standardized mean difference (SMD) was used to analyze the summary estimates for CPAP therapy. Results: Six articles with 168 patients were included in this meta-analysis, including five observational studies and one randomized controlled study. The meta-analysis showed that CPAP was associated with a statistically significant increase in IGF-1 in OSA patients (SMD = -0.436, 95% confidence interval = -0.653 to -0.218, P = 0.000). Conclusions: This meta-analysis suggested that CPAP therapy was associated with an increase in IGF-1 in patients with OSA. Further large-scale, well-designed interventional investigations are needed to clarify this issue. (C) 2014 Elsevier Ltd. All rights reserved.