Similarly, serum IGF-1 concentrations were lower in patients with OSAHS than those in patients in the control group in both case-control and cohort studies (SMD=-1.65, 95%CI= -2.23–1.08, P 0.001; SMD=-1.42, 95%CI=-2.78–0.07, P 0.001, Table 4). This evidence concerns the gene IGF1 and obstructive sleep apnea syndrome.