Table 3.

ORs of developing RA (overall) among subjects exposed to prolonged repetitive physical workload and cold work environment 5 years before baseline

		Cold work environment
Physical workload*		Unexposed		Exposed
		Cases/controls	OR (95% CI)	Cases/controls	OR (95% CI)	AP (95% CI)	p Value
Bending/turning	Unexposed	804/1799	1.0 (ref.)	84/88	2.1 (1.5 to 2.9)	−0.2 (−0.6 to 0.1)	0.190
	Exposed	1376/1925	1.5 (1.3 to 1.7)	313/339	2.1 (1.7 to 2.5)
Repetitive hand/finger movements	Unexposed	611/1223	1.0 (ref.)	131/193	1.4 (1.1 to 1.8)	0.3 (0.1 to 0.5)	<0.001
	Exposed	1566/2499	1.3 (1.2 to 1.5)	266/234	2.6 (2.1 to 3.2)
Carry more than 10 kg	Unexposed	1152/2265	1.0 (ref.)	49/60	1.7 (1.1 to 2.5)	0.0 (−0.4 to 0.3)	0.871
	Exposed	1026/1462	1.4 (1.2 to 1.5)	348/367	2.0 (1.7 to 2.4)
Hands below knee level	Unexposed	1846/3316	1.0 (ref.)	172/201	1.6 (1.3 to 2.0)	−0.1 (−0.3 to 0.2)	0.687
	Exposed	331/406	1.4 (1.2 to 1.7)	223/224	1.9 (1.6 to 2.4)
Vibration	Unexposed	1979/3407	1.0 (ref.)	175/211	1.5 (1.2 to 1.8)	0.2 (−0.1 to 0.4)	0.127
	Exposed	202/316	1.2 (1.0 to 1.5)	221/212	2.0 (1.6 to 2.5)
Hands above shoulder level	Unexposed	1682/3146	1.0 (ref.)	163/216	1.4 (1.0 to 1.8)	0.1 (−0.1 to 0.4)	0.226
	Exposed	495/578	1.5 (1.3 to 1.8)	234/210	2.3 (1.9 to 2.8)

Baseline is the year when the participants were recruited (ie, at the time when the patients were diagnosed).

*Missing information on 126 (3.4%) cases and 297 (5.0%) controls.

OR adjusted for age (10 strata), sex, residential area and recruitment time period (1996–2006 and 2006–2014).

AP, attributable proportion due to interaction; RA, rheumatoid arthritis.