Table 1.

Basic characteristics of cases and controls

Variable	Controls (n = 90,013)		RA cases (n = 22,677)
	N	%	N	%
Year of RA diagnosis
1995–1999	8086	9	2033	9
2000–2004	15,253	16.9	3849	17
2005–2009	24,713	27.5	6232	27.5
2010–2014	31,699	35.2	7980	35.2
2015–2017	10,262	11.4	2583	11.4
Age at index (years)
< 40	19,064	21.2	4857	21.4
40–59	20,416	22.7	5095	22.5
60–69	22,257	24.7	5588	24.6
70–79	19,238	21.4	4843	21.4
80–89	8366	9.3	2093	9.2
≥ 90	672	0.7	201	0.9
Mean age (SD)	61.4	(14.1)	61.4	(14.3)
Gender, female	60,620	67.3	15,276	67.4
Median follow-up before RA diagnosis (IQR)	10	(7–14)	10	(7–14)
Body mass index
Underweight	22,337	24.8	5102	22.5
Normal	2402	2.7	694	3.1
Overweight	28,948	32.2	7456	32.9
Obese	24,610	27.3	7308	32.2
Missing	11,716	13	2117	9.3
Smoking status
Never/ex-smokers	74,043	82.3	17,840	78.7
Current	15,970	17.7	4837	21.3
Alcohol
Never/ex-drinker	29,159	32.4	7341	32.4
1–10 units/weeks	46,692	51.9	11,976	52.8
> 10 units/week	14,162	15.7	3360	14.8
Charlson comorbidity index
0	56,683	63	12,813	56.5
1–2	24,356	27.1	7219	31.8
3–5	7937	8.8	2355	10.4
> 5	1037	1.2	290	1.3