Table 6.

Univariable and multivariable logistic regression for RA risk factors and ACPA positivity (≥6.2 U/mL) in all participants and after exclusion of RA participants

	Univariable			Multivariable
	OR	95% CI	p Value	OR	95% CI	p Value
All participants (n=40 136)
Age (years)	1.023	1.014 to 1.031	<0.001	1.013	1.003 to 1.022	0.007
Gender (female)	1.342	1.092 to 1.649	0.005	1.325	1.069 to 1.643	0.010
Smoking: pack years	1.023	1.015 to 1.030	<0.001	1.018	1.009 to 1.026	<0.001
Pack years, categories (%)
Never to 10	Ref.	Ref.	Ref.
>10–20	1.136	0.835 to 1.546	0.416
>20	2.311	1.763 to 3.030	<0.001
Smoking status
Never smoker	Ref.	Ref.	Ref.
Former smoker	1.532	1.221 to 1.923	0.000
Current smoker	1.499	1.164 to 1.929	0.002
Alcohol intake (g/day)	1.001	0.991 to 1.011	0.852
Joint complaints: pain and/or stiffness in hands and/or feet)	2.384	1.945 to 2.923	<0.001
Joint complaints: both pain and stiffness in hands and/or feet	2.976	2.390 to 3.705	<0.001	2.556	2.033 to 3.215	<0.001
Self-reported RA	15.083	11.800 to 19.281	<0.001
Defined RA	92.404	64.953 to 131.456	<0.001
Participants with RA excluded (n=39 298)
Age (years)	1.010	1.001 to 1.020	0.032	1.003	0.993 to 1.014	0.517
Gender (female)	1.211	0.962 to 1.524	0.104	1.289	1.014 to 1.639	0.038
Smoking: pack years	1.019	1.010 to 1.028	<0.001	1.019	1.009 to 1.028	<0.001
Pack years, categories (%)
Never to 10	Ref.	Ref.	Ref.
>10–20	1.070	0.752 to 1.524	0.706
>20	1.915	1.379 to 2.659	<0.001
Smoking status
Never smoker	Ref.	Ref.	Ref.
Former smoker	1.438	1.111 to 1.863	0.006
Current smoker	1.465	1.102 to 1.946	0.008
Alcohol intake (g/day)	0.995	0.983 to 1.008	0.463
Joint complaints: pain and/or stiffness in hands and/or feet)	1.364	1.055 to 1.764	0.018
Joint complaints: both pain and stiffness in hands and/or feet	1.422	1.040 to 1.943	0.027	1.275	0.923 to 1.762	0.140

Data are presented as ORs and CIs of the enter method. Forward and backward analyses resulted in comparable models with the same variables.

ACPA, anticitrullinated protein antibodies; RA, rheumatoid arthritis.