TABLE 2.

UNIVARIATE MORTALITY MODEL IN 609 PATIENTS WITH SEVERE EMPHYSEMA

Variable	n	Hazard Ratio (95% CI)	p Value
Demographic/Clinical
Age, yr
70–83	194	1.56 (1.23–2.32)	< 0.0001
40–69	415	Reference
Sex
Male	391	0.94 (0.63–1.19)	0.60
Female	218	Reference
Race
Non-white	35	1.06 (0.66–1.68)	0.82
White	574	Reference
Annual income
< $15,000	112	1.04 (0.77–1.39)	0.82
⩾ $15,000	496	Reference
BMI, kg/m2
High (⩾ 28.1)	123	0.77 (0.56–1.06)	0.11
Medium (reference)	362	Reference
Low (⩽ 21.4)	123	1.48 (1.13–1.95)	0.005
Oxygen use (rest, exercise, or sleeping)
Yes	495	1.80 (1.30–2.49)	< 0.001
No	114	Reference
Hemoglobin, g/dl
9.1–13.3	129	1.63 (1.26–2.12)	< 0.001
13.4–19.1	479	Reference
Health status
Quality of Well-Being (QWB)
0.16–0.49	122	1.47 (1.13–1.93)	0.005
0.50–0.89	487	Reference
SGRQ
65.3–88.8	122	1.62 (1.24–2.10)	< 0.001
18.7–65.2	487	Reference
UCSD SOBQ
79–109	131	1.89 (1.46–2.45)	< 0.001
9–78	478	Reference
Physiology
FEV1% predicted
11–21	150	1.44 (1.11–1.85)	0.005
22–54	459	Reference
TLC % predicted
140–203	131	1.07 (0.81–1.41)	0.65
95–139	478	Reference
Residual volume % predicted
262–412	124	1.41 (1.07–1.85)	0.01
97–261	485	Reference
IC/TLC
0.04–0.17	122	1.80 (1.39–2.34)	< 0.001
0.18–0.45	487	Reference
DlCO, % predicted
6–21	148	1.89 (1.48–2.41)	< 0.001
22–68	457	Reference
Pimax % predicted
3–17	138	1.12 (0.86–1.47)	0.39
18–57	462	Reference
Pemax % predicted
4–14	140	1.02 (0.78–1.34)	0.88
15–50	462	Reference
Arterial blood gas
PaO2, mm Hg
36–55	133	1.65 (1.28–2.13)	< 0.001
56–95	475	Reference
PaCO2, mm Hg
47–66	131	1.35 (1.04–1.77)	0.03
29–46	477	Reference
Exercise testing
Maximal 6MWT distance, m
144–288	123	2.02 (1.56–2.61)	< 0.001
289–652	486	Reference
Maximal CPET workload, W
Low*	271	2.20 (1.74–2.78)	< 0.001
High*	338	Reference
Computed tomography
Percent emphysema in whole lung†
25.7–48.5	111	1.14 (0.85–1.52)	0.38
0.4–25.6	441	Reference
Missing	57	0.96 (0.65–1.41)	0.82
Difference in % emphysema (upper lung:lower lung)†
−40.4 to −0.9	111	1.39 (1.04–1.85)	0.02
−0.8 to 63.6	441	Reference
Missing	57	0.99 (0.68–1.46)	0.98
Alpha for whole lung†
0.4–0.9	111	0.99 (0.73–1.34)	0.94
1.0–1.8	441	Reference
Missing	57	0.93 (0.63–1.36)	0.71
Difference in alpha (upper lung–lower lung)†
0.4 to 1.6	111	1.22 (0.91–1.64)	0.18
−1.6 to 0.3	441	Reference
Missing	57	0.97 (0.66–1.42)	0.87
Distribution of emphysema (radiologist)
Homogeneous	274	1.14 (0.90–1.43)	0.28
Heterogeneous	335	Reference
Nuclear perfusion scan
Perfusion ratio (upper lung:lower lung)
0.04–0.14	136	1.28 (0.98–1. 68)	0.07
0.15–3.13	472	Reference
Modified BODE index
7–10	139	2.38 (1.86–3.04)	< 0.001
1–6	469	Reference
Cigarette smoking, pack-years
90–280	126	1.15 (0.87–1. 51)	0.34
0.15–3.13	481	Reference
Nuclear perfusion scan
Duration since stopped smoking, yr
⩽ 2	127	1.14 (0.86–1. 51)	0.36
3–42	480	Reference

Definition of abbreviations: BMI = body mass index; CI = confidence interval; CPET = cardiopulmonary exercise testing; Dl_CO = diffusing capacity for carbon monoxide; IC/TLC = ratio of inspiratory capacity to total lung capacity; Pe_max = maximum expiratory pressure; Pi_max = maximum inspiratory pressure; QWB = Quality of Well-Being scale; 6MWT = 6-min-walk test; SGRQ = St. George's Respiratory Questionnaire; UCSD SOBQ = University of California, San Diego Shortness of Breath Questionnaire.

^*Low exercise is defined as a maximal workload at or below the sex-specific 40th percentile (25 W for females and 40 W for males); high exercise is defined as a workload above this threshold.

^†At the −950 Hounsfield unit cutoff.