Association between Dietary Vitamin A and HPV Infection in American Women: Data from NHANES 2003–2016

Table 3

Nonlinearity addressing by a weighted two-piecewise linear model.

Outcome:	HPV infection (OR (95% CI), value)
Fitting by standard linear model
Fitting by two-piecewise linear model	1.0 (0.9, 1.0), 0.199
Inflection point (K)	10.5
<10.5	0.9 (0.9, 1.0), 0.035
≧10.5	1.7 (1.1, 2.8), 0.018
Log-likelihood ratio	0.011