In predicting the risk of severe OSA compared with non-severe OSA, an α-Klotho cut-off value of 280.3 yielded a sensitivity of 84.44% and specificity of 75%, whereas an FGF-23 cut-off value of 75.5 yielded a sensitivity of 62.2% and specificity of 72.7%. Here, FGF23 is linked to obstructive sleep apnea syndrome.