Table 3.

Effect modification of the association between residential ${\mathrm{PM}}_{2.5}$ concentration (modeled as a continuous variable, 3-y mean, per IQR increase) and both overall and fatal incident MI in the Danish Nurse Cohort.

Variables	$n$	Overall incident MI	p-Valueb	$n$	Fatal incident MI	p-Valueb
		Model 3 [HR (95% CI)]a			Model 3 [HR (95% CI)]a
Age at baseline (y)
$<65$	472	1.00 (0.82, 1.20)		61	1.15 (0.68, 1.94)
$\ge 65$	169	1.17 (0.89, 1.53)	0.50	60	1.38 (0.92, 2.08)	0.71
Road traffic noise [dB (${\mathrm{L}}_{\text{den}}$)]c
Low ($<50.4$)	178	1.08 (0.81, 1.42)		36	1.95 (1.11, 3.41)
Medium (50.4–56.2)	211	1.03 (0.78, 1.37)		38	1.25 (0.66, 2.35)
High ($\ge 56.2$)	252	1.07 (0.87, 1.33)	0.70	47	1.28 (0.83, 1.99)	0.80
Obesityd
Not obese	592	1.06 (0.92, 1.23)		112	1.37 (1.01, 1.86)
Obese	49	0.87 (0.49, 1.52)	0.57	9	1.68 (0.42, 6.75)	0.87
Physical activity
Low	64	1.01 (0.68, 1.50)		26	1.46 (0.87, 2.45)
Medium	439	1.05 (0.88, 1.26)		78	1.27 (0.85, 1.89)
High	138	1.10 (0.78, 1.55)	0.71	17	1.61 (0.63, 4.07)	0.73
Smoking status
Never	170	0.92 (0.69, 1.23)		28	1.20 (0.66, 2.16)
Previous	164	1.25 (0.95, 1.66)		27	2.18 (1.19, 4.00)
Current	307	1.02 (0.83, 1.26)	0.63	66	1.16 (0.76, 1.77)	0.21
Hypertensione
No	462	1.01 (0.85, 1.20)		77	1.24 (0.85, 1.81)
Yes	179	1.09 (0.84, 1.43)	0.26	44	1.56 (0.95, 2.55)	1.00
Diabetese
No	620	1.02 (0.88, 1.18)		110	1.25 (0.90, 1.73)
Yes	21	2.15 (1.08, 4.25)	0.04	11	2.63 (0.76, 9.07)	0.27
Level of urbanization
Rural	289	0.92 (0.73, 1.15)		57	1.33 (0.82, 2.14)
Provincial	245	1.16 (0.91, 1.47)		47	1.30 (0.82, 2.08)
Urban	107	1.21 (0.90, 1.62)	0.60	17	1.48 (0.77, 2.77)	0.67
Menopausal status
Premenopausal	140	1.01 (0.69, 1.48)		15	1.63 (0.58, 4.58)
Postmenopausal	501	1.03 (0.88, 1.21)	0.25	106	1.32 (0.97, 1.80)	0.48

Note: Estimates are based on IQR increments of $5.3\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$. CI, confidence interval; HR, hazard ratio; IQR, interquartile range; ${\mathrm{L}}_{\mathrm{den}}$, joint expression of day (${\mathrm{L}}_{\mathrm{d}}$; 0700–1900 hours), evening (${\mathrm{L}}_{\mathrm{e}}$; 1900–2200 hours), and night (${\mathrm{L}}_{\mathrm{n}}$; 2200–0700 hours) road traffic noise levels, with 5 and $10\text{dB}$ penalties added to ${\mathrm{L}}_{\mathrm{e}}$ and ${\mathrm{L}}_{\mathrm{n}}$, respectively; MI, myocardial infarction; ${\mathrm{PM}}_{2.5}$, particulate matter with an aerodynamic diameter of $<2.5\mathrm{\mu }\mathrm{g}/{\mathrm{m}}^3$.

^aModel 3 was adjusted for age (underlying time), year of cohort entry (1993 or 1999), smoking status, pack-years, consumption of fruit, avoidance of fatty meat, alcohol consumption, use of oral contraceptives, use of hormone therapy, physical activity, marital status, employment status, level of urbanization, and ${\mathrm{L}}_{\text{den}}$.

^bFrom likelihood ratio test for interaction.

^cBased on Model 2: (Model 3, unadjusted for ${\mathrm{L}}_{\text{den}}$).

^dBody mass $\text{index}\ge 30$.

^eSelf-reported (diagnosed/medication for).