Factors contributing to quality of life in COPD patients in South Korea

Figures & data

Table 1 Basic characteristics of the study population

Characteristics	COPD patients (N=2,254,556)
Sex
Male, %	72.36 (0.12)
Age (yrs), mean	60.37 (0.34)
Age-groups (yrs), %
<40	5.67 (0.61)
40–49	13.08 (0.94)
50–59	25.96 (1.17)
60–69	28.93 (1.02)
70–79	22.78 (0.90)
80+	3.58 (0.41)
Income, %
Low	30.25 (1.14)
Middle	26.69 (1.15)
Upper middle	22.99 (1.12)
High	20.07 (1.09)
Education level, %
< Primary school	41.83 (1.27)
Middle school	17.76 (0.96)
High school	26.47 (1.17)
College +	13.95 (0.84)
Housing, %
Owners	73.54 (1.23)
Insurance type, %
NHI	95.61 (0.52)
Medical aid	4.39 (0.52)
Smoking, %
Current	51.08 (1.23)
Ex-smoker	19.62 (0.92)
Nonsmoker	29.30 (1.15)
Flu vaccination, %	48.92 (1.29)

Note: Standard errors in parentheses.

Abbreviations: NHI, National Health Insurance; yrs, years.

Table 2 Patient characteristics according to COPD severity (N=2,254,556)

Characteristics	GOLD criteria				Total (SE)	P-value
	I	II	III	IV
Sex
Male, %	31.40 (1.09)	36.58 (1.16)	3.97 (0.44)	0.41 (0.13)	72.36 (1.12)	P=0.0388
Female, %	9.88 (0.66)	15.87 (0.90)	1.72 (0.32)	0.17 (0.11)	27.64 (1.12)
Total	41.28 (1.12)	52.45 (1.14)	5.69 (0.54)	0.58 (0.17)
Age (yrs), mean	62.47 (0.47)	58.78 (0.45)	59.65 (1.72)	62.53 (3.08)	60.37 (0.34)	NS
Insurance type, %
NHI	39.87 (1.14)	50.14 (1.16)	5.03 (0.51)	0.56 (0.17)	95.61 (0.52)	P=0.0002
Medical aid	1.52 (0.30)	2.13 (0.34)	0.71 (0.23)	0.03 (0.02)	4.39 (0.52)
Housing, %
Owners	30.91 (1.05)	38.38 (1.14)	3.87 (0.43)	0.39 (0.14)	73.54 (1.23)	P=0.4814
Income level (household), %
Low	13.44 (0.80)	14.29 (0.84)	2.10 (0.34)	0.41 (0.13)	30.25 (1.14)
Middle	10.02 (0.73)	14.81 (0.86)	1.78 (0.30)	0.07 (0.06)	26.69 (1.15)
Upper middle	8.73 (0.75)	13.13 (0.85)	1.12 (0.30)	0.01 (0.01)	22.99 (1.12)
High	9.24 (0.72)	10.01 (0.82)	0.72 (0.23)	0.10 (0.10)	20.07 (1.09)
Education level, %
< Primary school	16.88 (0.83)	21.37 (0.98)	3.18 (0.42)	0.40 (0.13)	41.83 (1.27)	P=0.0037
Middle school	7.41 (0.63)	9.34 (0.74)	0.89 (0.20)	0.11 (0.10)	17.76 (0.96)
High school	11.56 (0.82)	13.62 (0.90)	1.26 (0.33)	0.03 (0.03)	26.47 (1.17)
College +	5.55 (0.55)	7.95 (0.66)	0.40 (0.13)	0.05 (0.05)	13.95 (0.84)
Smoking, %
Current	21.35 (0.98)	26.20 (1.05)	3.20 (0.41)	0.33 (0.12)	51.08 (1.23)	P=0.0004
Ex-smoker	9.90 (0.72)	8.84 (0.66)	0.83 (0.22)	0.04 (0.03)	19.62 (0.92)
Nonsmoker	10.16 (0.68)	17.23 (0.90)	1.69 (0.34)	0.22 (0.13)	29.30 (1.15)
Flu vaccination, %	20.82 (0.94)	24.09 (0.98)	3.57 (0.42)	0.44 (0.15)	48.92 (1.29)	P=0.0028
Diagnosed as COPD, %	0.13 (0.05)	1.16 (0.23)	0.97 (0.21)	0.19 (0.09)	2.46 (0.32)	P<0.0001
Comorbidities, %
Hypertension	13.27 (0.76)	16.41 (0.86)	1.78 (0.30)	0.33 (0.14)	31.79 (1.06)	P=0.3565
Diabetes mellitus	4.35 (0.42)	7.16 (0.58)	0.71 (0.22)	0.01 (0.01)	12.23 (0.70)	P=0.0990
Cancer	0.69 (0.15)	0.84 (0.22)	0.02 (0.02)	–	1.55 (0.28)	N/A
CV events	2.02 (0.31)	3.13 (0.41)	0.41 (0.12)	–	5.57 (0.54)	N/A
Osteoporosis	0.77 (0.17)	1.75 (0.27)	0.05 (0.04)	0.02 (0.02)	2.59 (0.32)	P=0.0337
Depressive disorder	1.42 (0.27)	1.38 (0.26)	0.32 (0.15)	0.02 (0.02)	3.15 (0.39)	P=0.2740

Note: Standard errors in parentheses.

Abbreviations: GOLD, Global Initiative for Chronic Obstructive Lung Disease; yrs, years; N/A, not applicable; SE, standard error; NHI, National Health Insurance; CV, cardiovascular; NS, not significant.

Figure 1 EQ-5D index among patients with COPD.

Abbreviations: EQ-5D, EuroQol-5D; GOLD, Global Initiative for Chronic Obstructive Lung Disease; HTN, hypertension; DM, diabetes melitus; CV, cardiovascular.

Table 3 Results of multivariate regression to predict factors associated with HRQOL in patients with COPD

Dependent variables	Estimates	SE	t-value
Intercept	0.910**	0.052	17.650
Sex
Male	0.034**	0.012	2.870
Female (ref)	–	–	–
Age	−0.001**	0.000	−3.280
Education
< Primary school	−0.049**	0.009	−5.350
Middle school	−0.009	0.009	−0.990
High school	−0.002	0.008	−0.250
College + (ref)	–	–	–
Income level
Low	−0.038**	0.009	−4.320
Middle	−0.008	0.008	−1.010
Upper middle	0.003	0.006	0.510
High (ref)	–	–	–
Diagnosed as COPD	−0.039	0.020	−1.940
Severity
II	0.003	0.006	0.560
III	−0.024	0.019	−1.300
IV	−0.100**	−0.049	−2.050
I (ref)	–	–	–
Comorbidities
Hypertension	−0.010	0.007	−1.420
Diabetes	−0.020*	0.010	−2.060
Depression	−0.089**	0.025	−3.630
Osteoporosis	−0.062**	0.022	−2.900
Cardiovascular events	−0.037**	0.014	−2.740
Cancer	0.005	0.015	0.290
Smoking
Current	−0.011	0.011	−0.960
Ex-smoker	0.004	0.012	0.290
Nonsmoker (ref)	–	–	–
R^2	0.1775

Note:

* P<0.05,

** P<0.001.

Abbreviations: HRQOL, health-related quality of life; SE, standard error; ref, reference.