. 2021 Mar 15;7(1):00567-2020. doi: 10.1183/23120541.00567-2020

TABLE 3.

Characteristics of study individuals (n=92) for lung mRNA analysis by real-time PCR

Characteristics	Never smokers (n=18)	Smokers without COPD (n=26)	COPD GOLD II (n=34)	COPD GOLD III–IV (n=14)
Sex male/female	6/12^#	19/7^#	31/3^#	8/6^#
Age years	65 (56–70)	63 (55–70)	66 (58–69)^§	56 (54–60)^¶^,⁺^,^§
Smoking status
Current smoker	na	16	22	0
Ex-smoker	na	10	12	14
Smoking pack-years	na	28 (15–45)^¶	45 (40–60)^¶^,^§	30 (25–30)^¶^,⁺^,^§
D_LCO mmol·min⁻¹·kPa⁻¹	21.58	23.30	17.22^¶	2.9^¶^,⁺^,^§
% predicted D_LCO	90.00	80.00	67.00^¶	35.00^¶^,⁺^,^§
D_LCO/V_A mmol·min⁻¹·kPa⁻¹·V_A⁻¹	4.64	3.89^¶	3.51^¶	0.87^¶^,⁺^,^§
% predicted D_LCO/V_A	102.85	91.00^¶	87.00^¶	58.50^¶^,⁺^,^§
% predicted FEV₁	102.00	95.00	68.00^¶^,^§	25.50^¶^,⁺^,^§
FEV₁/FVC %	78.00	75.00	56.00^¶^,^§	32.00^¶^,⁺^,^§

Data are presented as n, n/n or median (IQR). COPD: chronic obstructive pulmonary disease; GOLD: Global Initiative for Chronic Obstructive Lung Disease; na: not applicable; D_LCO: diffusing capacity of the lung for carbon monoxide; V_A: alveolar volume; FEV₁: forced expiratory volume in 1 s; FVC: forced vital capacity; IQR: interquartile range. ^#: p<0.001 (by Fisher's exact test); ^¶: p<0.05 versus never smokers (by Mann–Whitney U-test); ⁺: p<0.05 versus COPD GOLD II (by Mann–Whitney U-test); ^§: p<0.05 versus smokers without COPD (by Mann–Whitney U-test).