Table 4

Relative risks for all causes of death combined and for circulatory, digestive, respiratory and infectious diseases among 90 268 US radiological technologists according to work history derived from baseline questionnaire

	All-cause mortality			All heart diseases			Ischaemic heart disease			Cerebrovascular disease
	N	HR (95% CI)	p Value	N	HR (95% CI)	p Value	N	HR (95% CI)	p Value	N	HR (95% CI)	p Value
Year began working
1970+	1417	Reference	–	214	Reference	–	134	Reference	–	51	Reference	–
1960–1969	1987	0.99 (0.90 to 1.08)	0.76	385	1.05 (0.85 to 1.30)	0.63	248	1.04 (0.80 to 1.35)	0.78	74	0.83 (0.53 to 1.31)	0.42
1950–1959	2591	0.96 (0.86 to 1.06)	0.39	626	0.97 (0.77 to 1.22)	0.80	436	0.97 (0.73 to 1.28)	0.82	115	0.87 (0.53 to 1.44)	0.59
1940–1949	2286	0.99 (0.88 to 1.11)	0.86	681	1.02 (0.80 to 1.30)	0.87	458	0.98 (0.73 to 1.32)	0.89	161	1.02 (0.61 to 1.71)	0.95
<1940	904	1.06 (0.93 to 1.21)	0.42	310	1.22 (0.94 to 1.60)	0.14	215	1.31 (0.95 to 1.82)	0.10	104	1.40 (0.81 to 2.43)	0.23
		p Trend	0.36		p Trend	0.11		p Trend	(0.03)		p Trend	(0.02)
Age began working
30+	1630	Reference	–	488	Reference	–	313	Reference	–	116	Reference	–
25–29	1531	1.12 (1.05 to 1.21)	0.002	442	1.15 (1.01 to 1.32)	0.03	306	1.22 (1.04 to 1.44)	0.01	97	1.23 (0.94 to 1.62)	0.13
20–24	3605	1.03 (0.97 to 1.10)	0.36	840	1.03 (0.92 to 1.16)	0.61	580	1.10 (0.95 to 1.28)	0.19	181	1.12 (0.87 to 1.44)	0.37
<20	2419	0.97 (0.91 to 1.05)	0.46	446	0.92 (0.80 to 1.06)	0.26	292	0.97 (0.81 to 1.16)	0.71	111	1.14 (0.84 to 1.53)	0.40
		p Trend	0.60		p Trend	0.51		p Trend	0.97		p Trend	0.27
Total years worked
<10	3058	Reference	–	620	Reference	–	399	Reference	–	155	Reference	–
10–19	2884	1.07 (1.01 to 1.13)	0.02	625	1.13 (1.00 to 1.27)	0.04	417	1.17 (1.01 to 1.36)	0.03	151	1.08 (0.85 to 1.36)	0.53
20–29	1927	1.05 (0.98 to 1.12)	0.15	524	1.18 (1.04 to 1.34)	0.01	351	1.19 (1.02 to 1.39)	0.03	90	0.85 (0.65 to 1.13)	0.26
30+	1688	1.02 (0.95 to 1.10)	0.57	544	1.09 (0.96 to 1.25)	0.19	389	1.16 (0.98 to 1.36)	0.08	126	1.03 (0.79 to 1.35)	0.83
		p Trend	0.51		p Trend	0.15		p Trend	0.21		p Trend	0.91
Years worked before 1950
None	2905	Reference	–	782	Reference	–	555	Reference	–	144	Reference	–
1–4	1727	1.02 (0.95 to 1.09)	0.66	464	0.95 (0.83 to 1.09)	0.49	310	0.92 (0.78 to 1.08)	0.30	110	1.07 (0.80 to 1.42)	0.66
5+	1939	0.99 (0.91 to 1.06)	0.69	672	1.11 (0.97 to 1.27)	0.14	457	1.13 (0.96 to 1.33)	0.16	186	1.28 (0.97 to 1.69)	0.08
Ineligible	4603			784			493			153
		p Trend	0.89		p Trend	0.008		p Trend	0.005		p Trend	0.008
Years worked 1950–1959
None	2827	Reference	–	668	Reference	–	441	Reference	–	150	Reference	–
1–4	2237	0.93 (0.85 to 1.01)	0.06	532	0.89 (0.76 to 1.04)	0.14	353	0.86 (0.71 to 1.04)	0.11	109	0.95 (0.69 to 1.30)	0.74
5+	3974	1.03 (0.95 to 1.11)	0.51	1177	0.99 (0.86 to 1.15)	0.93	826	1.04 (0.87 to 1.24)	0.68	261	1.14 (0.84 to 1.55)	0.39
Ineligible	2122			318			188			67
		p Trend	0.07		p Trend	0.70		p Trend	0.91		p Trend	0.49
Years worked 1960–1969
None	3232	Reference	–	733	Reference	–	492	Reference	–	190	Reference	–
1–4	2204	1.04 (0.95 to 1.14)	0.41	453	1.14 (0.96 to 1.36)	0.13	291	1.00 (0.80 to 1.24)	0.98	106	0.76 (0.52 to 1.09)	0.13
5+	5417	1.13 (1.04 to 1.24)	0.01	1465	1.18 (0.99 to 1.40)	0.06	1007	1.12 (0.91 to 1.37)	0.28	283	0.84 (0.60 to 1.19)	0.33
Ineligible	264			28			12			5
		p Trend	0.03		p Trend	0.04		p Trend	0.08		p Trend	0.77
Years worked 1970 or later
None	2712	Reference	–	732	Reference	–	490	Reference	–	177	Reference	–
1–4	1273	0.97 (0.88 to 1.07)	0.52	267	0.87 (0.72 to 1.04)	0.12	182	0.93 (0.75 to 1.15)	0.48	79	1.34 (0.96 to 1.87)	0.09
5+	5572	0.90 (0.83 to 0.97)	0.01	1314	0.92 (0.80 to 1.06)	0.26	884	0.92 (0.78 to 1.10)	0.36	266	0.92 (0.68 to 1.24)	0.60
Ineligible	0			0			0			0
		p Trend	(0.004)		p Trend	0.16		p Trend	0.19		p Trend	0.35
Times held patient for X-ray
None	656	Reference	–	193	Reference	–	122	Reference	–	49	Reference	–
1–9	937	0.95 (0.86 to 1.05)	0.33	239	0.92 (0.76 to 1.12)	0.41	162	1.00 (0.79 to 1.27)	0.97	56	0.86 (0.59 to 1.27)	0.45
10–24	1166	0.89 (0.81 to 0.98)	0.01	281	0.83 (0.69 to 1.00)	0.05	184	0.86 (0.69 to 1.09)	0.21	68	0.83 (0.58 to 1.21)	0.33
25–50	1246	0.88 (0.80 to 0.97)	0.01	253	0.72 (0.60 to 0.87)	0.0008	173	0.78 (0.62 to 0.99)	0.04	55	0.66 (0.45 to 0.97)	0.04
50+	5201	0.96 (0.88 to 1.04)	0.31	1251	0.86 (0.74 to 1.01)	0.06	855	0.90 (0.74 to 1.09)	0.30	270	0.88 (0.64 to 1.20)	0.41
		p Trend	0.85		p Trend	0.12		p Trend	0.24		p Trend	0.64

	Digestive disease (non-malignant)			Respiratory disease (non-malignant)			Infectious disease
	N	HR (95% CI)	p Value	N	HR (95% CI)	p Value	N	HR (95% CI)	p Value
Year began working
1970+	41	Reference	–	61	Reference	–	25	Reference	–
1960–1969	80	1.53 (0.91 to 2.56)	0.11	126	0.91 (0.63 to 1.31)	0.60	14	0.38 (0.17 to 0.85)	0.02
1950–1959	82	1.43 (0.76 to 2.68)	0.26	239	0.73 (0.50 to 1.05)	0.09	20	0.49 (0.18 to 1.28)	0.14
1940–1949	56	1.25 (0.62 to 2.53)	0.53	243	0.64 (0.43 to 0.93)	0.02	18	0.56 (0.18 to 1.69)	0.30
<1940	28	1.78 (0.81 to 3.89)	0.15	103	0.67 (0.44 to 1.02)	0.06	7	0.91 (0.24 to 3.45)	0.89
		p Trend	0.76		p Trend	0.07		p Trend	0.86
Age began working
30+	39	Reference	–	188	Reference	–	18	Reference	–
25–29	42	1.22 (0.78 to 1.90)	0.38	151	1.10 (0.89 to 1.37)	0.38	15	0.79 (0.39 to 1.59)	0.51
20–24	129	1.37 (0.93 to 2.01)	0.11	266	0.88 (0.72 to 1.07)	0.21	32	0.65 (0.35 to 1.23)	0.19
<20	77	1.08 (0.70 to 1.67)	0.73	167	0.89 (0.70 to 1.12)	0.31	19	0.59 (0.28 to 1.23)	0.16
		p Trend	0.32		p Trend	0.37		p Trend	0.54
Total years worked
<10	89	Reference	–	216	Reference	–	22	Reference	–
10–19	101	1.20 (0.89 to 1.63)	0.23	225	1.22 (1.00 to 1.49)	0.05	33	1.84 (1.03 to 3.28)	0.04
20–29	65	1.28 (0.90 to 1.83)	0.17	172	1.07 (0.86 to 1.33)	0.52	15	1.57 (0.73 to 3.33)	0.25
30+	44	1.06 (0.69 to 1.62)	0.79	191	1.23 (0.98 to 1.54)	0.07	16	1.66 (0.75 to 3.71)	0.21
		p Trend	0.22		p Trend	0.42		p Trend	0.62
Years worked before 1950
None	90	Reference	–	313	Reference	–	24	Reference	–
1–4	44	0.83 (0.53 to 1.29)	0.40	192	0.94 (0.76 to 1.16)	0.55	14	1.28 (0.59 to 2.78)	0.53
5+	55	0.96 (0.62 to 1.50)	0.87	194	0.75 (0.60 to 0.94)	0.01	14	1.19 (0.50 to 2.82)	0.70
Ineligible	180			220			46
		p Trend	0.82		p Trend	0.24		p Trend	0.78
Years worked 1950–1959
None	89	Reference	–	228	Reference	–	1102	Reference	–
1–4	72	1.12 (0.68 to 1.84)	0.65	197	0.86 (0.67 to 1.12)	0.26	892	1.30 (0.54 to 3.15)	0.56
5+	119	1.05 (0.65 to 1.71)	0.84	439	1.06 (0.83 to 1.35)	0.63	1785	0.85 (0.34 to 2.12)	0.72
Ineligible	87			72			102
		p Trend	0.95		p Trend	0.45		p Trend	0.27
Years worked 1960–1969
None	95	Reference	–	246	Reference	–	31	Reference	–
1–4	78	0.99 (0.54 to 1.80)	0.97	138	0.90 (0.66 to 1.21)	0.47	18	1.22 (0.43 to 3.47)	0.71
5+	190	1.55 (0.91 to 2.64)	0.11	545	1.32 (1.01 to 1.73)	0.04	43	1.15 (0.42 to 3.20)	0.78
Ineligible	8			2			5
		p Trend	0.03		p Trend	0.14		p Trend	0.20
Years worked 1970 or later
None	70	Reference	–	266	Reference	–	14	Reference	–
1–4	48	1.30 (0.77 to 2.19)	0.33	111	0.93 (0.71 to 1.23)	0.62	13	2.66 (0.99 to 7.16)	0.05
5+	181	0.90 (0.57 to 1.42)	0.65	427	0.80 (0.63 to 1.00)	0.05	59	1.69 (0.68 to 4.21)	0.26
Ineligible	0			0			0
		p Trend	0.22		p Trend	0.13		p Trend	0.96
Times held patient for X-ray
None	15	Reference	–	54	Reference	–	6	Reference	–
1–9	26	1.15 (0.61 to 2.17)	0.68	81	1.16 (0.82 to 1.63)	0.41	10	1.02 (0.37 to 2.80)	0.98
10–24	40	1.28 (0.71 to 2.33)	0.41	78	0.85 (0.60 to 1.21)	0.37	8	0.65 (0.23 to 1.89)	0.43
25–50	43	1.24 (0.69 to 2.24)	0.48	107	1.10 (0.79 to 1.52)	0.59	11	0.88 (0.32 to 2.40)	0.80
50+	163	1.24 (0.73 to 2.13)	0.42	438	1.06 (0.80 to 1.42)	0.67	45	0.98 (0.42 to 2.33)	0.97
		p Trend	0.52		p Trend	0.64		p Trend	0.81

p Trends < 0.05 are in bold type.
All analyses used age as the timescale, were stratified by birth year and were adjusted for pack-years of cigarette smoking, BMI, race and gender. Analyses of year began working adjusted for total years worked, and vice versa. Analyses of number of years worked in a specific time period adjusted for numbers of years worked in all other time periods. Parenthesis around p trend value indicates significantly negative slope estimate.
BMI, body mass index.