Table 2. The association between chlamydia diagnosis and ethnicity estimated by logistic regression analysis among heterosexual participants attending the sexually transmitted infections outpatient clinic, Amsterdam, the Netherlands, in 2010.

		OR (95% CI)	P-value
Univariate		1.70 (1.21–2.39)	0.002
Adjusted for age and gendera		1.64 (1.16–2.31)	0.005
Adjusted for age, gender and sexual risk behaviour a,b,c		1.48 (1.00–2.18)	0.050
Adjusted for age, gender, education, and neighbourhood a , d		1.08 (0.71–1.64)	0.730
Adjusted for age, gender, sexual risk behaviour, ethnic mixing, education and neighbourhood a,b,c,d		0.97 (0.61–1.54)	0.910

OR = odds ratio; CI = confidence interval

^a Continuous variables like age, number of partners in the preceding year, and average partnership duration were modelled as a restricted cubic spline with knots on the 2.5^th, 25^th, 50^th, 75^th, and 97 5^th percentiles;

^b Sexual risk behaviour included the following covariates: number of partners in the preceding year, average partnership duration, concurrency, inconsistent or absent condom use with a steady partner, inconsistent or absent condom use with a casual partner, and ethnic mixing;

^c Log transformations were used to model the number of partners in the preceding year and the average partnership duration;

^d Education and neighbourhood were used as markers of socio-economic status.