Clinical characteristics of COPD syndrome: A 6-year follow-up study of adult smokers

Figures & data

Figure 1. Changes in chronic obstructive pulmonary disease (COPD) severities during the 6-year follow-up. COPD was classified according to the recommendations of the 2007 Global Initiative for Chronic Lung Disease (GOLD). The second visit (Visit 2) was organized 3 years after the baseline examination, and the last visit (Visit 3) after 6 years of follow-up.

Table I. Basic clinical characteristics of 513 study subjects from Northern Finland subdivided by GOLD 2007 COPD stages at the end of the 6-year follow-up study.

Variables	NLF (n = 328)	GOLD Stage 0 (n = 68)	GOLD Stage I (n = 49)	GOLD Stage II (n = 58)	GOLD Stages III–IV (n = 10)	Overall (n = 513)	P value
Gender							Chi-square test
Males	183 (60.4)	36 (11.9)	20 (9.6)	46 (15.2)	9 (3.0)	303 (100.0)	< 0.001
Females	145 (69.0)	32 (15.2)	20 (9.5)	12 (5.7)	1 (0.5)	210 (100.0)
							ANOVA
Age, years, mean (SD)	55.8 (8.3)	55.8 (8.6)	60.1 (9.1)	62.0 (9.0)	67.6 (5.1)	57.2 (8.8)	< 0.001
BMI, kg/m^2, mean (SD)	27.9 (4.1)	28.2 (4.9)	26.5 (4.3)	28.8 (4.0)	25.5 (5.4)	27.8 (4.3)	0.023
Pack years, mean (SD)	32.0 (15.0)	37.1 (17.7)	37.5 (18.3)	43.5 (14.6)	48.3 (18.9)	34.8 (16.3)	< 0.001
FEV1%, mean (SD)	93.4 (12.2)	90.2 (14.1)	87.9 (6.1)	66.8 (7.6)	40.3 (7.7)	88.4 (15.7)	na^a
FEV1/FVC%, mean (SD)	78.6 (5.0)	77.6 (4.5)	66.3 (3.6)	60.1 (6.9)	46.4 (9.1)	74.6 (9.1)	na
Cough, n (%)	27 (9.2)	68 (100.0)	11 (22.4)	20 (34.5)	4 (40.0)	130 (25.3)	na
Sputum production, n (%)	82 (25.0)	68 (100.0)	25 (51.0)	35 (60.3)	8 (80.0)	218 (42.5)	na

FEV₁% of predicted and FEV₁/FVC refer to the values after bronchodilator use.

NLF = normal lung function in spirometry with bronchodilatation test.

^ana = not applicable due to the inclusion of these variables in the definition of GOLD 2007 COPD stages.

Table II. Distribution of GOLD 2011 grades, symptoms, exacerbations, and hospitalizations subdivided according to GOLD 2007 stages of the 117 participants with chronic obstructive pulmonary disease after 6-year follow-up.

	GOLD Stage I (n = 49)	GOLD Stage II (n = 58)	GOLD Stages III–IV (n = 10)	All (n = 117)
GOLD 2011 grades, n (%)
Grade A	18 (36.7)	12 (20.7)	0	30 (25.6)
Grade B	30 (61.2)	38 (65.5)	0	68 (58.1)
Grade C	1 (2.0)	1 (1.7)	2 (20.0)	4 (3.4)
Grade D	0	7 (12.1)	8 (80.0)	15 (12.8)
mMRC ≥ 2, n (%)	9 (18.4)	32 (55.2)	7 (70.0)	48 (41.0)
CAT ≥ 10, n (%)	28 (57.1)	38 (65.5)	7 (70.0)	73 (62.4)
CAT ≥ 10 and mMRC ≥ 2, n (%)	7 (14.3)	25 (43.1)	6 (60.0)	38 (32.5)
CAT < 10 and mMRC ≥ 2, n (%)	2 (4.1)	7 (12.1)	1 (10.0)	10 (8.5)
CAT ≥ 10 and mMRC < 2, n (%)	21 (42.9)	13 (22.4)	1 (10.0)	35 (29.9)
CAT < 10 and mMRC < 2, n (%)	19 (38.8)	13 (22.4)	2 (20.0)	34 (29.1)
Number of patients experiencing exacerbations during the last follow-up year, n (%)
None	43 (87.8)	41 (70.7)	7 (70.0)	91 (77.8)
One	6 (12.2)	13 (22.4)	1 (10.0)	20 (17.1)
Two	0	1 (1.7)	1 (10.0)	2 (1.7)
Three	0	3 (5.2)	1 (10.0)	4 (3.4)
Hospitalizations, n (%)	1 (2.0)	5 (8.6)	2 (20.0)	8 (6.8)

Figure 2. Distribution of COPD Assessment Test (CAT) score by COPD status at the end of the 6-year follow-up study of 513 participants. P value of one-way ANOVA linear test was < 0.001.

Figure 3. Percentage distribution of the modified British Medical Research Council (mMRC) categories of the 513 participants at the 6-year follow-up visit subdivided by their COPD status. P value of chi-square test for linear trend was < 0.001.

Figure 4. Scatterplot of forced expiratory volume in 1 second (FEV₁) versus FEV₁/FVC in spirometry with bronchodilatation test. COPD is classified by GOLD 2007 recommendations in the study with 513 participants. Stage 0 refers to cases with normal lung function and with chronic bronchitis. Unclassified COPD refers to FEV₁ (%) < 80% predicted and FEV₁/FVC (%) > 70% in BD spirometry.