Table 2

Associations between emphysema on CT, per cent emphysema, and mortality due to lung disease in the Multi-Ethnic Study of Atherosclerosis, 2000–2013

Underlying cause of death	Emphysema on CT (dichotomous)			Per cent emphysema (continuous)
Underlying cause of death	Absent (N=6233)	Present (N=538)	p Value	All (N=6784)	p Value
Respiratory diseases
Deaths	57	18		77
Person-years	71 845	6078		77 750
Mortality rate per 10 000 person-years	7.9	29.6		9.9
HR_crude (95% CI)	1.00 (referent)	3.67 (2.16–6.25)	<0.001	1.48 (1.35–1.63)	<0.001
HR_adjusted (95% CI)	1.00 (referent)	2.94 (1.68–5.15)	<0.001	1.51 (1.35–1.69)	<0.001
CLRD
Deaths	20	17		39
Person-years	71 845	6078		77 750
Mortality rate per 10 000 person-years	2.8	28.0		5.0
HR_crude (95% CI)	1.00 (referent)	10.11 (5.25–19.46)	<0.001	1.71 (1.55–1.88)	<0.001
HR_adjusted (95% CI)	1.00 (referent)	9.54 (4.70–19.35)	<0.001	1.78 (1.57–2.03)	<0.001
Lung cancer
Deaths	76	19		95
Person-years	71 845	6078		77 750
Mortality rate per 10 000 person-years	10.6	31.3		12.2
HR_crude (95% CI)	1.00 (referent)	2.81 (1.70–4.65)	<0.001	1.35 (1.20–1.52)	<0.001
HR_adjusted (95% CI)	1.00 (referent)	1.84 (1.09–3.12)	0.023	1.21 (1.06–1.38)	0.006
All lung diseases
Deaths	133	37		172
Person-years	71 845	6078		77 750
Mortality rate per 10 000 person-years	18.5	60.9		22.1
HR_crude (95% CI)	1.00 (referent)	3.16 (2.20–4.56)	<0.001	1.42 (1.32–1.53)	<0.001
HR_adjusted (95% CI)	1.00 (referent)	2.25 (1.54–3.30)	<0.001	1.34 (1.23–1.46)	<0.001

The end points were defined by an underlying cause of death of respiratory disease (J00–J99), lung cancer (C33–C34) and, combining these, all lung disease. We also specifically examined mortality due to CLRD (J40–47), which was defined as deaths with COPD, emphysema, chronic bronchitis or asthma as the underlying cause, or, in the context of pneumonia as the underlying cause (J12–18), with these diseases (J40–47) recorded as a contributing cause.
For per cent emphysema, HRs reported per IQR (4.5%), which is equivalent to the difference between the third quartile (5.7%) and the first quartile (1.2%) of per cent emphysema. Models adjusted for baseline age, sex, race/ethnicity, body mass index, site, smoking status, pack-years of smoking, coronary artery calcium score and educational attainment. Upper limit of normal for per cent emphysema defined by reference equations.
CLRD, chronic lower respiratory disease.