Oxidative stress and lung function profiles of male smokers free from COPD compared to those with COPD: a case-control study

Figures & data

Table 1 Clinical characteristics of the two groups: smokers’ Non-COPD and COPD

		Non-COPD (n=29)	COPD (n=16)
Anthropometric, physical activity, and tobacco use data (Data are mean±SD [95%CI])
Age (years)		47.93±5.66 [45.77–50.8]	48.99±5.33 [46.15–51.83]
Height (m)		1.73±0.07 [1.70–1.75]	1.67±0.06 [1.63–1.70]^a
Weight (kg)		83±17 [77–90]	68±14 [60–78]^a
Body mass index (kg/m2)		27.93±4.95 [26.04–29.82]	24.57±5.24 [21.77–27.36]^a
Household activity score		1.36±0.53 [1.16–1.56]	0.88±0.31 [0.71–1.05]^a
Sporting activity score		4.42±4.84 [2.57–6.26]	0.33±0.54 [0.04–0.62]^a
Leisure activity score		2.53±1.63 [1.92–3.15]	1.64±0.58 [1.34–1.95]^a
Physical activity score		8.31±4.86 [6.46–10.16]	2.86±0.78 [2.44–3.27]^a
Cigarettes use (PY)		27±14 [22–33]	30±19 [20–41]
Obesity, socioeconomic status, clinical, and pathological data (data are number (percentage))
Obesity status	Obese	10 (34.5)	2 (12.5)
	Non-obese	19 (65.5)	14 (87.5)
Schooling level	High	20 (68.9)	6 (37.5)^b
	Low	9 (31.0)	10 (62.5)^b
Socioeconomic level	Favorable	13 (44.8)	5 (31.2)
	Unfavorable	16 (55.2)	11 (68.7)
Cough	Yes	11 (37.9)	45 (25.0)
	No	18 (62.1)	12 (75.0)
Sputum	Yes	10 (34.5)	6 (37.5)
	No	19 (19.5)	10 (62.5)^b
Dyspnea	Yes	12 (12.4)	8 (50.0)^b
	No	17 (58.6)	8 (50.0)
Chest pain	Yes	6 (20.7)	2 (12.5)
	No	23 (79.3)	14 (87.5)
Whistling	Yes	3 (10.3)	1 (06.2)
	No	26 (89.7)	15 (93.7)
Recent respiratory infection	Yes	0 (0.0)	2 (12.5)
	No	29 (100)	14 (87.5)
Emphysema	Yes	0 (0.0)	0 (0.0)
	No	29 (100)	16 (100)
Diabetes	Yes	0 (0.0)	0 (0.0)
	No	29 (100)	16 (100)
High blood pressure	Yes	2 (6.90)	3 (18.5)
	No	27 (93.1)	13 (81.2)
Cardiovascular diseases	Yes	0 (0.0)	0 (0.0)
	No	29 (100)	16 (100)
Surgical history	Yes	3 (10.3)	0 (0.0)
	No	26 (89.7)	16 (100)

^a p<0.05 (t-test): Non-COPD versus COPD. ^b p<0.05 (chi-square test): Non-COPD versus COPD.

Table 2 Fractional exhaled nitric oxide (Fe_NO) and plethysmographic data of the two groups: smokers’ Non-COPD and COPD

		Non-COPD (n=29)	COPD (n=16)
First-second-forced-expiratory-volume (FEV1)	L	3.11±0.47 [2.93–3.29]	2.05±0.67 [1.69–2.41]^a
	%	88±10 [84–92]	62±18 [53–72]^a
Forced vital capacity (FVC)	L	4.14±0.62 [3.90–4.37]	3.47±0.90 [3.00–3.95]^a
	%	95±11 [91–99]	87±18 [77–96]
FEV1/FVC	(absolute value)	0.75±0.043.91 [0.74–0.77]	0.58±0.08 [0.54–0.63]^a
Mid maximal expiratory flow	L	2.56±0.65 [2.31–2.80]	1.02±0.46 [0.78–1.26]^a
	%	64±15 [58–70]	26±11 [21–32]^a
Slow vital capacity	L	4.09±0.63 [3.85–4.33]	3.46±0.86 [3.01–3.92]^a
	%	90±12 [86–95]	83±16 [75–92]
Total lung capacity	L	5.86±1.25 [5.38–6.33]	5.71±0.96 [5.20–6.22]
	%	87±16 [81–93]	92±14 [84–99]
Residual volume	L	1.94±1.23 [1.47–2.41]	2.14±0.73 [1.75–2.53]
	%	92±56 [71–113]	106±38 [86–126]
Thoracic gas volume	L	3.71±1.52 [3.13–4.28]	3.78±0.91 [3.30–4.26]
	%	109±43 [93–125]	117±29 [101–132]
FeNO	ppb	13.83±7.11 [11.12–16.53]	14.88±6.95 [11.17–18.58]

Plethysmographic data are measured before use of bronchodilator and expressed in absolute values and as percentage of predicted values. Data are mean±SD [95% confidence interval]. ^a p<0.05 (t-test): Non-COPD versus COPD.

Table 3 Correlation coefficient between fractional exhaled nitric oxide (Fe_NO) and lung function data and physical activity score in the two groups: smokers’ Non-COPD (n=29) and COPD (n=16)

		FeNO (ppb)
First-second-forced-	Non-COPD	−0.04
expiratory-volume (%)	COPD	0.14
Total lung capacity (%)	Non-COPD	−0.06
	COPD	−0.48^a
Residual volume (%)	Non-COPD	0.01
	COPD	−0.44
Physical activity score	Non-COPD	0.12
	COPD	−0.12

Plethysmographic data were measured before bronchodilator use and were expressed as percentages of references values. ^ap<0.05 (Pearson product-moment correlation coefficient).

Fig 1.  Oxidative stress levels of the two groups: smokers Non-COPD (Non-COPD) and smokers COPD patients (COPD). a) Malondialdehyde (MDA) level measured in 26 Non-COPD and 15 COPD smokers. b) Glutathione (GSH) level measured in 24 Non-COPD and 15 COPD smokers. c) Protein sulfhydryl (PSH) level measured in 24 Non-COPD and 16 COPD.

Data are shown as box-and-whisker plots illustrating the mean (), ±standard-error (), and 95% confidence interval (). p (t-test): comparison of levels of oxidative stress markers between the two groups.

Table 4 Oxidative stress markers of the two groups (smokers’ Non-COPD and COPD) divided according to the obesity status

		Non-COPD (n=29)		COPD (n=16)
		Non-obese (n=19)	Obese (n=10)	Non-obese (n=14)	Obese (n=2)
Malondialdehyde	(µmol/l)	15.74±1.22	15.89±1.55	13.50±1.60	7.75±2.42^a
Fractional exhaled nitric oxide	(ppb)	14.21±1.73	13.10±2.08	14.21±1.92	19.50±1.50
Protein sulfhydryl	(µg/g of hemoglobin)	58.77±13.30	44.95±17.46	23.99±5.28^a	37.80±18.18
Glutathione	(µg/mL)	45.50±8.42	33.40±6.07	20.46±3.43^a	52.00±36.00^b

Data are mean±SE. Non-obese (body mass index (BMI) <30 kg/m²). Obese (BMI≥30 kg/m²). ^a p<0.05 (t-test): Non-COPD versus COPD for the same obesity status (Non-obese or Obese). ^b p<0.05 (t-test): Non-obese versus Obese for the same group (Non-COPD or COPD).

Table 5 Correlation coefficient between oxidative stress markers and lung function data and physical activity score in the two groups: smokers’ Non-COPD (n=29) and COPD (n=16)

		MDA	GSH	PSH
First-second-forced-expiratory-volume (%)	Non-COPD	−0.23	0.03	0.15
	COPD	−0.02	−0.21	−0.46
Total lung capacity (%)	Non-COPD	−0.10	−0.17	0.03
	COPD	−0.08	−0.49	−0.50^a
Residual volume (%)	Non-COPD	0.04	0.22	0.41^a
	COPD	−0.12	−0.15	0.08
Fractional exhale nitric oxide (ppb)	Non-COPD	−0.16	0.21	0.14
	COPD	−0.05	0.36	0.10
Physical activity score	Non-COPD	−0.14	0.47^a	0.62^a
	COPD	0.10	0.11	−0.14

Plethysmographic data were measured before bronchodilator use and were expressed as percentages of references values. MDA: Malondialdehyde (µmol/l) was determined in 26 Non-COPD and 15 COPD smokers; GSH: Glutathione (µg/mL) was determined in 24 Non-COPD and 15 COPD smokers; PSH: Protein sulfhydryl (µg/g of hemoglobin) was determined in 25 Non-COPD and 16 COPD smokers. ^a p<0.05 (Pearson product–moment correlation coefficient).