Clinical significance of self-reported cough intensity and frequency in patients with interstitial lung disease: a cross-sectional study

Table 3 Unadjusted analysis of factors associated with cough frequency in patients with interstitial lung disease

Variable	IIPs (n = 70)		CTD-ILD (n = 49)		CHP (n = 10)		Combined
Variable	ρ	p-value	ρ	p-value	ρ	p-value	ρ	p-value
Age, years	0.017	0.890	0.222	0.125	−0.031	0.933	0.100	0.260
Male sex	–	0.174	–	0.441	–	0.667	–	0.415
Current smoker	–	0.079	–	0.857	–	–	–	0.037
Pack-years of smoking	−0.013	0.916	−0.192	0.186	−0.107	0.769	−0.011	0.898
Body mass index^a	−0.251	0.036	−0.174	0.232	0.326	0.391	−0.166	0.061
FSSG score	0.019	0.878	0.350	0.014	0.342	0.334	0.174	0.049
MRC chronic dyspnoea scale^b	0.071	0.561	0.291	0.042	0.356	0.312	0.173	0.051
Pulmonary function tests, % predicted^c
FEV₁	−0.083	0.508	−0.040	0.786	0.038	0.923	−0.098	0.279
FVC	−0.160	0.201	−0.114	0.439	0.017	0.966	−0.120	0.187
TLC	−0.236	0.056	0.028	0.849	−0.126	0.748	−0.172	0.057
D_LCO	−0.307	0.012	−0.287	0.048	−0.510	0.160	−0.328	< 0.001
Composite Physiologic Index^c	0.334	0.006	0.322	0.026	0.259	0.500	0.319	< 0.001
Medication
Glucocorticoid	–	0.642	–	0.096	–	0.257	–	0.012
Antifibrotic agent	–	0.362	–	–	–	0.066	–	0.049
Proton pump inhibitor	–	0.847	–	0.241	–	0.915	–	0.582

The Spearman rank correlation was used to assess correlations between the data. The p-values for binary variables were determined using the Mann-Whitney U test. CHP, chronic hypersensitivity pneumonia; CTD-ILD, connective tissue disease-associated interstitial lung disease; D_Lco, diffusing capacity of the lung for carbon monoxide; FEV₁, forced expiratory volume in 1 s; FSSG, frequency scale for the symptoms of gastro-oesophageal reflux disease; FVC, forced vital capacity; IIPs, idiopathic interstitial pneumonias; MRC, Medical Research Council; TLC, total lung capacity. ^aIIPs (n = 70), CTD-ILD (n = 49), CHP (n = 9); ^bIIPs (n = 69), CTD-ILD (n = 49), CHP (n = 10); ^cIIPs (n = 66), CTD-ILD (n = 48), CHP (n = 9)

ISSN: 1471-2466