Table 4.

Predictive factors for archiving MCID in the LCQ assessed using the Logistic Regression Model.

Variable	Univariate analysis		Multivariate analysis*
	OR (95% CI)	P value	OR (95% CI)	P value
Age, yr	1.081 (0.922–1.269)	.337
Male	1.588 (0.144–17.561)	.706
Weight	1.096 (0.991–1.212)	.073
Height	1.158 (1.006–1.332)	.041	1.158 (1.006–1.332)	.041
Body mass index	1.106 (0.820–1.493)	.508
Never smoker	Ref.	.
Ever-smokers	N/E	N/E
Pack-yr	1.037 (0.993–1.083)	.098
GAP point	2.313 (0.838–6.385)	.105
Antifibrotic agent	N/E	.N/E
Duration of PFD	1.001 (0.997–1.005)	.543
Dyspnea, mMRC	1.717 (0.656–4.491)	.271
Pulmonary function test
FVC, % predicted	0.987 (0.945–1.031)	.555
FEV1, % predicted	0.990 (0.946–1.035)	.648
DLco, % predicted	0.966 (0.904–1.032)	.308
Six-minute walk test
Distance (m)	0.998 (0.992–1.004)	.421
Initial SpO2 (%)	1.303 (0.843–2.015)	.233
Nadir SpO2 (%)	1.034 (0.912–1.174)	.601
Arterial oxygen pressure	0.997 (0.968–1.026)	.821
PaCO2 (mm Hg)	0.973 (0.800–1.183)	.784
WBC	0.774 (0.495–1.212)	.263
IL-6	0.888 (0.731–1.080)	.235
CRP	0.203 (0.014–2.961)	.244

CI = confidence interval, CRP = C-reactive protein, DLco = diffusing capacity of the lungs for carbon monoxide, FEV₁ = forced expiratory volume in one second, FVC = forced vital capacity, GAP = gender-age-pulmonary function, IL-6 = interleukin-6, LCQ = Leicester cough questionnaire, MCID = minimal clinically important differences, mMRC = modified medical research council, N/E = not estimable since none was observed in a certain subgroup, OR = odds ratio, PaCO₂ = partial pressure of carbon dioxide, PFD = Pirfenidone, Ref = reference group, SpO₂ = saturation of percutaneous oxygen, WBC = white blood cell.

^*In a multivariate logistic regression, the statistically significant variables were selected in a backward elimination method with 0.05 alpha level.