Table 3.
Associations between percent emphysema and mortality due to lung disease in the Multi-Ethnic Study of Atherosclerosis, stratified by airflow limitation, 2000–2013.
| Underlying cause of death | Percent emphysema as continuous exposure in persons with valid spirometry measures | P-interaction for airflow limitation | ||||
|---|---|---|---|---|---|---|
| Airflow limitation (N=863) | P-value | No airflow limitation (N=2,965) | P-value | |||
| Respiratory diseases | ||||||
| Deaths | 8 | 12 | 0.597 | |||
| Person-years | 6,418 | 22,843 | ||||
| Mortality rate per 10,000 person-years | 12.5 | 5.3 | ||||
| Hazard Ratio (95% CI) | ||||||
| Hazard Ratiocrude (95% CI) | 1.38 (0.87–2.19) | 0.171 | 1.41 (0.79–2.50) | 0.244 | ||
| Hazard Ratioadjusted (95% CI) | 1.32 (0.98–1.78) | 0.069 | 1.30 (0.58–2.94) | 0.525 | ||
| Hazard Ratioextended (95% CI) | 1.40 (1.02–1.93) | 0.038 | 2.38 (1.01–5.60) | 0.047 | ||
| Lung cancer | ||||||
| Deaths | 18 | 18 | 0.593 | |||
| Person-years | 6,418 | 22,843 | ||||
| Mortality rate per 10,000 person-years | 28.1 | 7.9 | ||||
| Hazard Ratio (95% CI) | ||||||
| Hazard Ratiocrude (95% CI) | 1.39 (1.03–1.88) | 0.031 | 1.03 (0.58–1.85) | 0.920 | ||
| Hazard Ratioadjusted (95% CI) | 1.31 (0.89–1.93) | 0.170 | 1.14 (0.58–2.24) | 0.709 | ||
| Hazard Ratioextended (95% CI) | 1.52 (1.01–2.28) | 0.046 | 1.56 (0.82–2.96) | 0.172 | ||
| All lung diseases | ||||||
| Deaths | 26 | 30 | 0.930 | |||
| Person-years | 6,418 | 22,843 | ||||
| Mortality rate per 10,000 person-years | 40.5 | 13.1 | ||||
| Hazard Ratio (95% CI) | ||||||
| Hazard Ratiocrude (95% CI) | 1.39 (1.08–1.78) | 0.011 | 1.18 (0.79–1.78) | 0.413 | ||
| Hazard Ratioadjusted (95% CI) | 1.32 (0.98–1.78) | 0.071 | 1.16 (0.71–1.90) | 0.542 | ||
| Hazard Ratioextended (95% CI) | 1.38 (1.01–1.90) | 0.044 | 1.63 (1.02–2.61) | 0.043 | ||
The endpoints were defined by an underlying cause of death of respiratory disease (J00–J99), lung cancer (C33–C34) and, combining these, all lung disease. We do not report mortality due to chronic lower respiratory disease (CLRD; J40–47) due to very low event rates in this group (N=6 and N=2 in persons with and without airflow limitation, respectively).
Hazard ratios reported per interquartile range (4.5%), which is equivalent to the difference between the third quartile (5.7%) and the first quartile (1.2%) of percent 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. Interaction terms are reported for this adjusted model. The extend model is additionally adjusted for the forced expiratory volume in one second (FEV1), absence/presence of restriction on spirometry, and log-transformed volume of high attenuation areas.