Relationship between 25-hydroxyvitamin D and IGF1: a cross-sectional study of the Third National Health and Nutrition Examination Survey participants

Table 4 Comparison of the linear and nonlinear fitting models

	IGF1 (β 95% CI)	P value
Fitting model by standard linear regression	0.16 (0.04, 0.29)	0.0103
Fitting model by two-piecewise linear regression inflection point of 25OHD	75
≤ 75	0.43 (0.25, 0.62)	< 0.0001
> 75	−0.53 (−0.90, −0.15)	0.0057
P for log-likelihood ratio test		< 0.001

Age, sex, race, exercise, smoking behavior, alcohol intake, diabetes, serum calcium level, and BMI were adjusted for in the model
Abbreviation: insulin-like growth factor 1 (IGF1), 25-hydroxyvitamin D (25OHD), body mass index (BMI)

ISSN: 2072-1315