Table 4.

Association between patient characteristics at enrollment and respiratory-related hospitalization

	Univariable model		Multivariable model		Parsimonious model
	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
Female	1.12 (0.87, 1.44)	0.374	1.24 (0.95, 1.61)	0.124
Age		< 0.001		< 0.001		< 0.001
< 62 years, per 5-year increase	0.62 (0.50, 0.77)	< 0.001	0.73 (0.58, 0.91)	0.005	0.68 (0.55, 0.84)	< 0.001
≥ 62 years, per 5-year increase	0.99 (0.90, 1.09)	0.810	0.91 (0.82, 1.01)	0.068	0.92 (0.83, 1.01)	0.085
Hispanic/Latino ethnicity	2.21 (1.34, 3.66)	0.002	1.43 (0.84, 2.45)	0.189
Body mass index, per 1-point increase	0.98 (0.96, 1.00)	0.070	0.95 (0.93, 0.98)	< 0.001	0.96 (0.93, 0.98)	< 0.001
Current/former smoker	1.01 (0.79, 1.29)	0.927	1.04 (0.80, 1.36)	0.763
Private insurance	1.00 (0.79, 1.27)	0.987	0.95 (0.72, 1.24)	0.689
Diagnostic criteria of definite IPFa	1.06 (0.83, 1.35)	0.645	1.10 (0.86, 1.42)	0.440
FVC % predicted, per absolute 10% increase	0.82 (0.76, 0.89)	< 0.001	0.93 (0.85, 1.01)	0.080	0.90 (0.83, 0.97)	0.005
DLco % predicted, per absolute 10% increase	0.75 (0.69, 0.83)	< 0.001	0.90 (0.80, 1.00)	0.057
Oxygen use at rest	2.88 (2.24, 3.70)	< 0.001	2.32 (1.65, 3.25)	< 0.001	2.85 (2.18, 3.72)	< 0.001
Oxygen use with activity	2.31 (1.84, 2.91)	< 0.001	1.32 (0.96, 1.80)	0.087
History of coronary artery disease or congestive heart failure	0.83 (0.66, 1.06)	0.133	0.87 (0.67, 1.13)	0.300
History of pulmonary hypertension	2.37 (1.63, 3.43)	< 0.001	1.69 (1.10, 2.60)	0.016	2.02 (1.37, 2.96)	< 0.001
History of emphysema	1.11 (0.80, 1.55)	0.530	0.79 (0.54, 1.15)	0.216
History of sleep apnea	1.00 (0.78, 1.28)	0.989	1.19 (0.90, 1.57)	0.221
Hospitalization in 12 months prior to enrollment	1.17 (0.91, 1.50)	0.221	0.91 (0.69, 1.20)	0.501

Multivariable model included all the covariates listed. Parsimonious model included covariates selected after performing backwards selection on the multivariable model

^aAccording to 2011 ATS/ERS/JRS/ALAT diagnostic guidelines [24]