Table 5.

Risk of SCD among young firefighters (age ≥ 45) engaged in emergency and strenuous duties compared with firefighters engaged in non-emergency duties: Analysis stratified on history of cardiovascular condition^a

Duty	Firefighters with a positive history of cardiovascular conditionb					Firefighters without a history of cardiovascular conditionb
	Observed deaths (N = 33)	Statistic				Observed deaths (N = 54)	Statistic
	n (%)	Ec	O/E	IRR	95% CI	n (%)	Ec	O/E	IRR	95% CI
Fire station and other non-emergency duties	3 (9)	16.8	0.2	1.0	Ref.	13 (24)	22.4	0.6	1.0	Ref.
EMS and other non-fire emergencies	1 (3)	7.6	0.1	0.7	0.1–7.1	4 (7)	10.1	0.4	0.7	0.2–2.1
Physical training	12 (36)	2.6	4.6	25.5	7.2–90.4	15 (28)	3.5	4.3	7.4	3.5–15.5
Alarm return	5 (15)	3.3	1.5	8.5	2.0–35.6	4 (7)	4.4	0.9	1.6	0.5–4.8
Alarm response	2 (6)	2.0	1.0	5.7	1.0–33.9	2 (4)	2.6	0.8	1.3	0.3–5.8
Fire suppression	10 (30)	0.7	15.2	85.0	23.4–308	16 (30)	0.9	18.2	31.4	15.1–65.2

E, expected; IRR, incidence rate ratio; O, observed; Ref, reference category.

^aData from NIOSH Fire Fighter Fatality Investigation and Prevention Program (1996–2012).

^bIncludes history of irregular rhythm, CHD or equivalent, valvular disease, abnormal electrocardiogram, chest pain or shortness of breath.

^cExpected deaths based on municipal data from the Cambridge Fire Department, Cambridge, MA [2].