TABLE 5.

Adjusted regression coefficients (95% confidence interval) between HRV parameters and POD, stratified by age.

	Young-old, n = 251 (85.37%)		Old-old, n = 43 (14.63%)
Variables	aOR	95% CI	aOR	95% CI
SDNNI (ms)	0.972	(0.943, 1.002)	0.980	(0.914, 1.051)
HF (nu)	0.993	(0.964, 1.023)	0.968	(0.924, 1.014)
LF (nu)	1.005	(0.974, 1.038)	1.003	(0.957, 1.051)
VLF (ms)	0.999	(0.998, 1.001)	0.998	(0.994, 1.002)
ULF (ms)	0.970	(0.942, 0.999)	0.981	(0.891, 1.079)

Adjusted variables: sex, BMI, education, CCI, surgery, dosage of midazolam, and equivalent morphine. aOR, adjusted odds ratio; SDNNI, mean of the standard deviations of all the NN intervals for each 5-min segment of a 24-h HRV recording; HF, high frequency; LF, low frequency; VLF, very low frequency; ULF, ultra-low frequency; HRV, heart rate variability; POD, postoperative delirium; BMI, body mass index; CCI, Charlson Comorbidity Index.