Risk/benefit tradeoff of habitual physical activity and air pollution on chronic pulmonary obstructive disease: findings from a large prospective cohort study

Table 2 Associations of habitual physical activity (PA) and long-term PM_2.5 exposure and COPD incidence (n = 6381) in UK Biobank Cohort

Levels ^a		Model l ^b	Model 2 ^b	Model 3 ^b	Model 4 ^b
Levels ^a		HR (95% CI)	HR (95% CI)	HR (95% CI)	HR (95% CI)
Self-reported PA	Case
Low	1495	1.000	1.000	1.000	1.000
Moderate	2530	0.758 (0.711, 0.809)	0.761 (0.713, 0.812)	0.769 (0.721, 0.820)	0.769 (0.720, 0.820)
High	2409	0.752 (0.705, 0.803)	0.713 (0.668, 0.761)	0.725 (0.678, 0.775)	0.726 (0.679, 0.776)
P for trend	–	<0.0001	<0.0001	<0.0001	<0.0001
Per 600 MET-min/week increment	6434	0.990 (0.985, 0.996)	0.986 (0.980, 0.991)	0.987 (0.981, 0.993)	0.987 (0.982, 0.993)
Objectively measured PA
Low	253	1.000	1.000	1.000	1.000
Moderate	434	0.676 (0.589, 0.777)	0.754 (0.655, 0.867)	0.757 (0.657, 0.871)	0.757 (0.658, 0.872)
High	403	0.542 (0.462, 0.636)	0.637 (0.540, 0.752)	0.635 (0.538, 0.750)	0.635 (0.538, 0.750)
P for trend	–	<0.0001	<0.0001	<0.0001	<0.0001
Per IQR increment	1090	0.658 (0.602, 0.72)	0.741 (0.677, 0.812)	0.743 (0.678, 0.814)	0.743 (0.679, 0.814)
PM_2.5 levels
Low	1959	1.000	1.000	1.000	1.000
Moderate	2164	1.215 (1.143, 1.292)	1.059 (0.995, 1.127)	1.052 (0.989, 1.119)	1.050 (0.987, 1.117)
High	2311	1.448 (1.363, 1.538)	1.094 (1.025, 1.167)	1.072 (1.005, 1.144)	1.068 (1.001, 1.140)
P for trend	–	<0.0001	0.007	0.036	0.046
Per IQR increment (1.27 μg/m³)	6434	1.243 (1.209, 1.278)	1.080 (1.046, 1.115)	1.067 (1.034, 1.101)	1.065 (1.032, 1.099)

The bold type represents the statistically significant differences (p < 0.05)
Abbreviations: PM_2.5 particulate matter with aerodynamic diameter < 2.5 μm, HR hazard ratio, CI confidence interval, PA physical activity, COPD chronic obstructive pulmonary disease
^a: PM_2.5 exposure levels (low, moderate, and high) were defined by PM_2.5 tertiles (< 9.48 μg/m³, 9.48 to 10.27 μg/m³, and ≥ 10.27 μg/m³), self-reported PA levels were defined according to a standard scoring criteria of International Physical Activity Questionnaire (IPAQ): low (< 600 MET-min/week), moderate (600 to 3000 MET-min/week), and high (≥ 3000 MET-min/week), and objectively measured PA levels were defined by objectively measured PA tertiles [< 24.32 milli-gravity (mg), 24.32 to 30.70 mg, and ≥ 30.70 mg]
^b Model 1 was adjusted for age at enrolment, sex, and ethnicity. Model 2 was further adjusted for household income, employment status, education, and Townsend deprivation index. Model 3 was further adjusted for lifestyle factors (smoking status, alcohol intake frequency, fruit and vegetable intake), body mass index (BMI), and secondhand smoke exposure. And Model 4 was further mutually adjusted by PA (effect estimation of PM_2.5) or PM_2.5 (effect estimation of PA)

ISSN: 1741-7015