. 2024 Mar 30;39(4):393–407. doi: 10.1007/s10654-024-01110-y

Table 1.

Study population description by gender, age, age at recruitment and smoking exposure variables

Study	Full sample					PLCO					ATBC
Characteristics	Cases		Controls		P^a	Cases		Controls		P^a	Cases		Controls		P^a
Characteristics	N	(%)	N	(%)		N	(%)	N	(%)		N	(%)	N	(%)
Total	766	47.9	832	52.1		288	48.3	308	51.7		478	47.7	524	52.3
Sex					0.568					0.604
Male	704	91.9	771	92.7		226	78.5	247	80.2		478	100	524	100
Female	62	8.1	61	7.3		62	21.5	61	19.8		0	0	0	0
Age at randomisation (years)					0.737					0.850					0.330
49–54	150	19.6	174	20.9		0	0	0	0		150	31.4	174	33.2
55–59	229	29.9	238	28.6		67	23.3	66	21.4		162	33.9	172	32.8
60–64	217	28.3	248	29.8		101	35.1	110	35.7		116	24.3	138	26.3
65–69	133	17.4	128	15.4		85	29.5	88	28.6		48	10.0	40	7.6
70–74	37	4.8	44	5.3		35	12.2	44	14.3		2	0.4	0	0
Smoking status					2.95E − 08					2.49E − 10
Never	69	9.0	153	18.4		69	24.0	153	49.7		0	0	0	0
Former	167	21.8	128	15.4		167	58.0	128	41.6		0	0	0	0
Current	530	69.2	551	66.2		52	18.1	27	8.8		478	100	524	100
Pack-years of Smoking					8.41E − 13					3.43E − 11					2.37E − 08
< 1	70	9.1	154	18.5		70	24.3	154	50.0		0	0	0	0
1–20	116	15.2	201	24.2		50	27.4	48	15.6		66	13.8	153	29.2
21–40	270	35.2	235	28.2		56	29.4	51	16.6		214	44.8	184	35.1
41–60	198	25.8	154	18.5		55	29.1	35	11.4		143	29.9	119	22.7
> 60	109	14.2	85	10.2		54	18.8	17	5.5		55	11.5	68	13.0
Missing	3	0.4	3	0.4		3	1.0	3	1.0		0	0	0	0
Smoking duration (years)					3.17E − 09					7.12E − 10					3.28E − 04
0	69	9.0	153	18.4		69	24.0	153	49.7		0	0	0	0
1–15	43	5.6	59	7.1		35	12.2	29	0.4		8	1.7	30	5.8
16–30	150	19.6	172	20.7		62	21.5	57	18.5		88	18.4	115	21.7
31–45	416	54.3	353	42.4		88	30.6	47	15.3		328	68.6	306	58.4
46–60	78	10.2	52	6.2		31	10.8	17	5.5		47	10.2	35	6.6
Missing	10	1.3	43	5.2		3	1.0	5	1.6		7	1.5	38	7.5
Smoking intensity (packs/day)					6.48E − 07					1.27E − 10					0.0246
0	69	9.0	153	18.4		69	24.0	153	49.7		0	0	0	0
> 0 and ≤ 1	415	54.2	399	48.0		116	40.3	90	29.2		299	62.6	309	59.0
> 1 and ≤ 2	244	31.9	211	25.4		80	27.8	59	19.2		164	34.3	152	29.0
> 2 and ≤ 3	30	3.9	27	3.2		22	7.6	3	1.0		8	1.7	24	4.6
> 3 and ≤ 4	1	0.1	2	0.2		1	0.3	1	0.3		0	0	1	0.2
Missing	7	0.9	40	4.8		0	0.0	2	0.6		7	1.5	38	7.3

Results are presented for the full 1598 included participants, and for each of the contributing study separately

p-values were derived from a chi-square test investigating potential differences in the distribution of each factors in cases and controls