Table 1

Description of the sample

	Diagnosis
	Sarcoidosis		Asthma		COPD		Other		All referents		Total
	N	Per cent	N	Per cent	N	Per cent	N	Per cent	N	Per cent	N	Per cent
Male	391	57.2	386	46.1	190	52.9	148	57.6	724	49.8	1115	52.2
Completed high school	548	80.1	663	79.1	198	55.2	181	70.4	1042	71.9	1590	74.4
Black ethnicity	15	2.2	3	0.4	2	0.6	0	0.0	5	0.3	20	0.9
First-degree relative with sarcoidosis	36	5.3	7	0.8	2	0.6	4	1.6	13	0.9	49	2.3
Never smoked*	401	58.8	469	56.0	64	18.0	111	43.5	644	44.5	1045	49.1
1–250 cigarette year	185	27.1	200	23.9	62	17.5	48	18.8	310	21.4	495	23.2
250<500 cigarettes year	47	6.9	92	11.0	72	20.3	42	16.5	206	14.2	253	11.9
≥500 cigarettes year	49	7.2	77	9.2	157	44.2	54	21.2	288	19.9	337	15.8
Median age	44.3		44.0		51.4		50.6		47.1		46.2
N	684	100.0	838	100.0	359	100.0	257	100.0	1454	100.0	2138	100.0