CST3 and obstructive sleep apnea syndrome: In the IVW approach, after adjusting for obesity, the casual relationship of OSA and eGFRcystatin c (OR = 0.995, 95% CI: 0.975–1.015, P = .626), BUN levels (OR = 1.039, 95% CI: 0.971–1.112, P = .269), and cystatin C levels (OR = 1.022, 95% CI: 0.919–1.136, P = .687) disappeared.