Plasma Cathepsin S and Cathepsin S/Cystatin C Ratios Are Potential Biomarkers for COPD

Table 2

Simple regression analysis.

	Cathepsin S		Cystatin C		Cat S/Cys C (/10^3)
Age	0.033	0.72	0.226			0.16
Pack-Year	0.099	0.27	0.096	0.29		0.99
BMI	0.175	0.052		0.65	0.132	0.14
Serum Cr	0.164	0.07	0.266			0.30
% VC		0.997		0.55	0.076	0.40
FEV1/FVC	0.261			0.88	0.242
% FEV1 predicted	0.179			0.83	0.188
PEF	0.083	0.36		0.07	0.199
	0.131	0.15		0.23	0.187
%   predicted	0.089	0.37			0.277
%	0.197			0.23	0.244
LAA			0.033	0.71
mPA	0.112	0.24	0.139	0.14		0.58
abAo	0.181	0.06	0.267		0.045	0.64
Current/Ex (51/74)	24.8/22.8	0.17	2.78/2.65	0.44	9.77/9.42	0.65
HT () (22/103)	24.5/23.4	0.57	2.74/2.70	0.57	9.68/9.54	0.85
ICS () (17/108)	20.1/24.2	0.06	2.59/2.72	0.59	8.36/9.75	0.21
(116/9)	23.7/23.4	0.93	2.66/3.32		9.69/7.90	0.22

; . Cat: cathepsin; Cys: cystatin; BMI: body mass index; Cr: creatinine; VC: vital capacity; FEV₁/FVC: ratio of forced expiratory volume in 1 second to forced vital capacity; FEV₁: forced expiratory volume in 1 second; PEF: peak expiratory flow rate; : the air flow rate at 50% vital capacity; : diffusing capacity of the lung for carbon monoxide; : diffusing capacity of the lung for carbon monoxide divided by the alveolar volume; LAA: low attenuation area; mPA: main pulmonary artery; abAo: abdominal aorta; Ex: ex-smoker; HT: hypertension; ICS: inhaled corticosteroid; : male; : female.