ALB and myalgic encephalomeyelitis/chronic fatigue syndrome: The area under the curve (AUC) of age, sex, BMI, ASA PS, serum albumin, the GnRI, CCI, CFS, and the Koval index were 0.457 (95% CI 0.388–0.526; p = 0.223), 0.467 (95% CI 0.397–0.538; p = 0.352), 0.565 (95% CI 0.493–0.637; p = 0.065), 0.605 (95% CI 0.539–0.672; p = 0.003), 0.647 (95% CI 0.576–0.717; p < 0.001), 0.561 (95% CI 0.488–0.634; p = 0.083), 0.648 (95% CI 0.580–0.715; p < 0.001), 0.523 (95% CI 0.321–0.725; p = 0.828), and 0.486 (95% CI 0.373–0.599; p = 0.808), respectively.