Table 4.

Threshold effect analysis of serum carotenoids on VAI using piece-wise linear regression

VAI		Adjusted β (95% CI) P value
α-carotene
One line slop		−0.26 (− 0.31, − 0.20) < 0.0001
Log likelihood ratio test		0.071
β-carotene
Inflection point (K)		2.44
<K slope		−0.63 (− 0.89, − 0.37) < 0.0001
>K slope		−0.33 (− 0.40, − 0.25) < 0.0001
Log likelihood ratio test		0.038
β-cryptoxanthin
One line slop		−0.24 (− 0.32, − 0.17) < 0.0001
Log likelihood ratio test		0.447
Lutein/zeaxanthin
One line slop		−0.26 (− 0.37, − 0.15) < 0.0001
Log likelihood ratio test		0.354
Trans-lycopene
Inflection point (K)		3.80
<K slope		−0.11 (− 0.27, 0.06) 0.1966
>K slope		−0.47 (− 0.62, − 0.33) < 0.0001
Log likelihood ratio test		0.005

Adjusted for age, sex, race, education level, marital status, alcohol intake, smoking status, leisure-time physical activity, BMI, the family of poverty ratio, TC, hypertension, diabetes, and CVD.