Table 3.

Association between patient characteristics at enrollment and hospitalization

	Univariable model		Multivariable model		Parsimonious model
	HR (95% CI)	p-value	HR (95% CI)	p-value	HR (95% CI)	p-value
Female	1.02 (0.85, 1.24)	0.804	1.08 (0.89, 1.32)	0.424
Age		0.017		0.217
< 62 years, per 5-year increase	0.79 (0.65, 0.95)	0.014	0.84 (0.68, 1.02)	0.079
≥ 62 years, per 5-year increase	1.09 (1.02, 1.17)	0.018	1.02 (0.95, 1.10)	0.568
Hispanic/Latino ethnicity	1.23 (0.78, 1.92)	0.372	1.16 (0.72, 1.86)	0.541
Body mass index, per 1-point increase	0.99 (0.97, 1.01)	0.287	0.99 (0.97, 1.01)	0.180
Current/former smoker	1.27 (1.06, 1.52)	0.010	1.23 (1.02, 1.49)	0.033
Private insurance	0.82 (0.69, 0.98)	0.029	0.84 (0.70, 1.02)	0.072	0.84 (0.70, 1.00)	0.046
Diagnostic criteria of definite IPFa	0.96 (0.80, 1.14)	0.630	0.96 (0.80, 1.14)	0.624
FVC % predicted, per absolute 10% increase	0.89 (0.84, 0.94)	< 0.001	0.95 (0.89, 1.01)	0.101
DLco % predicted, per absolute 10% increase	0.83 (0.77, 0.88)	< 0.001	0.92 (0.85, 1.00)	0.056	0.87 (0.81, 0.93)	< 0.001
Oxygen use at rest	1.99 (1.63, 2.44)	< 0.001	1.46 (1.12, 1.91)	0.005	1.63 (1.31, 2.03)	< 0.001
Oxygen use with activity	1.69 (1.42, 2.01)	< 0.001	1.21 (0.95, 1.53)	0.122
History of coronary artery disease or congestive heart failure	1.19 (1.00, 1.42)	0.046	1.14 (0.95, 1.38)	0.161
History of pulmonary hypertension	1.21 (0.88, 1.66)	0.239	0.87 (0.62, 1.22)	0.429
History of emphysema	1.09 (0.85, 1.40)	0.476	0.95 (0.73, 1.23)	0.686
History of sleep apnea	0.97 (0.81, 1.17)	0.751	0.96 (0.79, 1.18)	0.722
Hospitalization in 12 months prior to enrollment	1.51 (1.25, 1.83)	< 0.001	1.30 (1.06, 1.58)	0.011	1.30 (1.08, 1.58)	0.007

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]