Decade of decline: Unraveling Helicobacter pylori trends in Northwest China

Table 3 Results of the two-piecewise linear regression model

Item	OR (95%CI)	P value
Total
Fitting model by standard linear regression	1.00 (1.00-1.00)	< 0.001a
Fitting model by two-piecewise linear regression
Inflection points of age	29.64
< 29.64	1.06 (1.05-1.06)	< 0.001a
≥ 29.64	0.99 (0.99-0.99)	< 0.001a
P for likelihood test		< 0.001a
Male
Fitting model by standard linear regression	1.00 (1.00-1.00)	< 0.001a
Fitting model by two-piecewise linear regression
Inflection points of age	28.00
< 28.00	1.05 (1.04-1.06)	< 0.001a
≥ 28.00	0.99 (0.99-1.00)	< 0.001a
P for likelihood test		< 0.001a
Female
Fitting model by standard linear regression	1.00 (1.00-1.00)	0.018a
Fitting model by two-piecewise linear regression
Inflection points of age	30.89
< 30.89	1.06 (1.05-1.07)	< 0.001a
≥ 30.89	0.99 (0.99-0.99)	< 0.001a
P for likelihood test		< 0.001a

^aP < 0.05.

OR: Odds ratio.