Table 3.

Threshold effect analysis between the first meal time and the prevalence of gallstones.

Two-piecewise logistic regression model1	OR (95% CI)	P	P for non-linearity
FMT ≤ 13.4 h	1.07 (1.03 ~ 1.12)	0.002	0.042
FMT > 13.4 h	1.04 (0.90 ~ 1.19)	0.617

The two-piecewise logistic regression analysis identified threshold effect between the FMT and the presence of gallstones. ¹Sex, age, race, education level, marital status, PIR, BMI, physical activity level, alcohol use, smoking status, diabetes status, hypertension status, energy level, protein intake, carbohydrate intake, dietary fiber intake, total fat intake, total saturated fatty acid intake, and cholesterol intake were adjusted. FMT, first meal time; PIR, ratio of family income to poverty.