Table 3

Adjusted HRRs and 95% CIs for cardiovascular disease among 3499 welders according to accumulated exposure to particles

Cardiovascular disease	Cumulative particulate exposure (mg/m³×years)	N^*	No. of cases	HRR^†	95% CI
Acute myocardial infarct	0–10 (reference)	37991	17	1	–
	10–50	163075	67	1.11	0.65 to 1.89
	50–100	184292	96	1.43	0.85 to 2.41
	>100	150199	80	1.03	0.61 to 1.74
		Log-rank test, χ²=5.95, p=0.114 Test for trend, χ²=0.00, p=0.969
Angina pectoris	0–10 (reference)	44954	17	1	–
	10–50	194825	80	1.23	0.73 to 2.08
	50–100	226162	107	1.41	0.84 to 2.36
	>100	181557	95	1.21	0.72 to 2.03
		Log-rank test, χ²=2.26, p=0.521 Test for trend, χ²=0.22, p=0.637
Chronic ischaemic heart disease	0–10 (reference)	31613	7	1	–
	10–50	131588	61	2.51	1.15 to 5.49
	50–100	162675	83	2.79	1.29 to 6.04
	>100	143045	60	1.70	0.78 to 3.72
		Log–rank test, χ²=13.56, p=0.004 Test for trend, χ²=0.27, p=0.606
Cerebral infarct	0–10 (reference)	15477	7	1	–
	10–50	63815	32	1.32	0.58 to 3.01
	50–100	76279	32	1.17	0.52 to 2.67
	>100	66747	52	1.54	0.70 to 3.39
		Log-rank test, χ²=2.44, p=0.486 Test for trend, χ²=1.12, p=0.290

Results for welders who answered all the questions necessary for calculation of their cumulative exposure across all years and who answered questions about smoking, alcohol consumption and use of medicines.
↵* Numbers correspond to data split on every incidence of each disease for all welders, in order to include the time-dependent variable, duration of welding after baseline. As each man contributed a different number of years for each incidence, each was included more than once in the analysis.
↵† Adjusted for calendar year, tobacco smoking, alcohol consumption and use of hypertension or ‘heart’ medicine.