Table 2.

Unadjusted and Adjusted Hazard Ratio for Death by Geographic Region

Geographic region	Model 1a			Model 2b			Model 3c
	Hazard ratio	CI	P value	Hazard ratio	CI	P value	Hazard ratio	CI	P value
Large fringe metro (suburban)	Reference	Reference	Reference	Reference	Reference	Reference	Reference	Reference	Reference
Large central metro (inner city)
0-1 years	0.84	0.52-1.34	.5	0.92	0.57-1.49	.7	0.84	0.50-1.43	.5
≥1 years	0.99	0.74-1.32	> .9	1.02	0.76-1.37	.9	0.84	0.61-1.17	.3
Medium/small metro
0-1 years	1.05	0.69-1.61	.8	1.19	0.77-1.82	.4	0.88	0.55-1.40	.6
≥1 years	1.03	0.79-1.36	.8	1.14	0.86-1.51	.4	0.74	0.54-1.01	.06
Rural
0-1 years	1.67	0.93-3.01	.09	1.80	0.98-3.31	.06	0.87	0.39-1.91	.7
≥ 1 years	1.0	0.62-1.60	> .9	1.18	0.73-1.92	.5	0.79	0.47-1.35	.4

^aUnadjusted analysis.

^bAdjusted for individual-level covariates: age, gender, race/ethnicity, COPD diagnosis, smoking history, antifibrotic use.

^cAdjusted for individual-level characteristics and pulmonary function at time of referral: age, gender, race/ethnicity, COPD diagnosis, smoking history, antifibrotic use, FVC % predicted with the use of the Global Lung Initiative “Other” reference equation, diffusion capacity for carbon monoxide percent predicted with the use of the Global Lung Initiative reference equation.