Comorbidity and health-related quality of life in patients with severe chronic obstructive pulmonary disease attending Swedish secondary care units

Figures & data

Figure 1 Comorbidity score and health-related quality of life. Unadjusted mean EQ-5D index, EQ-5D VAS score, and CAT total score in relation to the number of treated comorbid conditions.

Abbreviations: CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; VAS, visual analog scale.

Figure 2 Correlations between EQ-5D and CAT. scatter plots of the correlations between CAT total score and, respectively, EQ-5D index and EQ-5D VAS score.

Abbreviations: CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; VAS, visual analog scale.

Table 1 Patient characteristics

Patient characteristics	Male (n=165)	Female (n=208)	P-value
Age	72.2 (±8.11)	70.5 (±7.58)	0.047
Smoking habits
Never smoker	4 (2.4%)	6 (2.9%)	0.841
Ex-smoker	130 (78.8%)	171 (82.2%)	Ref
Smoker	31 (18.8%)	30 (14.4%)	0.275
Pack years	38.3 (±20.7)	30.9 (±16.1)	<0.0001
FEV1% pred	35.1 (±8.59)	34.5 (±8.78)	0.566
COPD stage
III	121 (73.3%)	138 (66.3%)	Ref
IV	44 (26.7%)	70 (33.7%)	0.146
BMI
<22.0	38 (23.0%)	76 (36.5%)	0.005
≥22, <30	105 (63.6%)	106 (51.0%)	Ref
≥30.0	22 (13.3%)	26 (12.5%)	0.623
Exacerbations in the past year
0	72 (43.6%)	69 (33.3%)	Ref
1	34 (20.6%)	47 (22.7%)	0.193
≥2	59 (35.8%)	91 (44.0%)	0.045
Chronic bronchitis	60 (36.4%)	78 (37.5%)	0.821
Cardiovascular disease	108 (65.5%)	115 (55.3%)	0.047
Diabetes	23 (13.9%)	17 (8.2%)	0.074
Renal impairment	8 (4.8%)	6 (2.9%)	0.322
Musculoskeletal symptoms	27 (16.4%)	63 (30.3%)	0.002
Osteoporosis	25 (15.2%)	78 (37.5%)	<0.0001
Depression	16 (9.7%)	46 (22.1%)	0.001
EQ-5D index	0.71 (±0.23)	0.60 (±0.30)	<0.0001
EQ-5D VAS	58.8 (±18.7)	54.7 (±22.5)	0.066
CAT total score	17.0 (±6.81)	19.7 (±7.43)	<0.0001

Notes: Patient characteristics distributed by sex. Data presented as mean ± standard deviations or numbers (%) of characteristics compared with remaining study population.

Abbreviations: BMI, body mass index; CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; FEV₁% pred, FEV₁ as a percentage of predicted value; VAS, visual analog scale.

Table 2 Associations between HRQL response variables and explanatory variables

Explanation variables	HRQL response variables
	EQ-5D index	P-value	EQ-5D VAS	P-value	CAT	P-value
Sex (female)	−0.07 (−0.12 to −0.02)	0.007			2.35 (0.98 to 3.72)	0.001
Age	−0.003 (−0.007 to 0.000)	0.027
FEV1% pred	0.008 (0.005 to 0.010)	<0.0001	0.61 (0.38 to 0.85)	<0.0001	−0.13 (−0.21 to −0.05)	0.001
Exacerbations in the past year
0	Ref				Ref
1	−0.02 (−0.08 to 0.05)	0.611			0.32 (−1.51 to 2.15)	0.730
≥2	−0.14 (−0.20 to −0.08)	<0.0001			2.74 (1.16 to 4.32)	0.001
Chronic bronchitis	−0.07 (−0.13 to −0.02)	0.005	−5.17 (−9.42 to −0.92)	0.017	3.78 (2.35 to 5.20)	<0.0001
Musculoskeletal symptoms	−0.08 (−0.14 to −0.02)	0.006
Osteoporosis			−4.65 (−9.27 to −0.03)	0.049
Depression	−0.10 (−0.17 to −0.04)	0.002

Notes: Adjusted regression coefficients (95% confidence interval) for explanatory variables included in the three final models. Empty spaces denote variables not included in the final model of the respective HRQL instrument.

Abbreviations: CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; FEV₁% pred, FEV₁ as a percentage of predicted value; HRQL, health-related quality of life; VAS, visual analog scale.

Figure 3 Chronic bronchitis and health-related quality of life. Unadjusted mean EQ-5D index, EQ-5D VAS score, and CAT total score (with 95% confidence intervals) in patients with and without chronic bronchitis.

Abbreviations: CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; VAS, visual analog scale.

Table 3 Associations between comorbid conditions and HRQL by patient sex

	Male	P-value	Female	P-value	P-value interaction
Chronic bronchitis
EQ-5D index	−0.03 (−0.10 to 0.04)	0.342	−0.10 (−0.18 to −0.03)	0.009	0.104
EQ-5D VAS	−4.60 (−10.0 to 1.24)	0.122	−5.19 (−11.3 to 0.96)	0.098	0.809
CAT	2.65 (0.60 to 4.70)	0.012	4.40 (2.43 to 6.37)	<0.0001	0.212
Musculoskeletal symptoms
EQ-5D index	−0.03 (−0.12 to 0.06)	0.498	−0.10 (−0.18 to −0.02)	0.010	0.162
Osteoporosis
EQ-5D VAS	2.09 (−5.72 to 9.91)	0.598	−6.39 (−12.6 to -0.18)	0.044	0.090
Depression
EQ-5D index	−0.05 (−0.17 to 0.06)	0.363	−0.12 (−0.21 to −0.04)	0.004	0.205

Note: Adjusted regression coefficients (95% confidence interval) from stratified final models.

Abbreviations: CAT, COPD assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; HRQL, health-related quality of life; VAS, visual analog scale.

Table S1 Associations between explanatory variables and health-related quality of life response variables

Explanatory variables	EQ-5D index unadjusted	EQ-5D index adjusted	EQ-5D VAS unadjusted	EQ-5D VAS adjusted	CAT unadjusted	CAT adjusted
Sex (female)	−0.11 (−0.16 to−0.05)	−0.07 (−0.12 to−0.02)	−4.04 (−8.34 to 0.26)	−1.87 (−6.44 to 2.70)	2.73(1.26 to 4.20)	1.85 (0.32 to 3.38)
Age	−0.003 (−0.006 to −0.001)	−0.003 (−0.006 to 0.001)	−0.11 (−0.39 to 0.16)	−0.15 (−0.44 to 0.14)	−0.01 (−0.10 to 0.09)	0.05 (−0.05 to 0.14)
Pack years	0.000 (−0.001 to 0.002)	0.000 (−0.001 to 0.002)	0.01 (−0.11 to 0.13)	−0.02 (−0.14 to 0.10)	−0.01 (−0.05 to 0.03)	−0.02 (−0.06 to 0.03)
FEV1% pred	0.007 (0.004 to 0.010)	0.007 (0.004 to 0.010)	0.67(0.43 to 0.91)	0.64 (0.38 to 0.89)	−0.18 (−0.26 to −0.09)	−0.1 2 (−0.20 to −0.03)
BMI
<22	−0.13 (−0.19 to −0.07)	−0.05 (−0.10 to 0.01)	−5.59 (−10.4 to −0.79)	−0.72 (−5.75 to 4.31)	2.52 (0.87 to 4.17)	0.93 (−0.76 to 2.62)
≥22 to <30	Ref	Ref	Ref	Ref	Ref	Ref
≥30	−0.05 (−0.13 to 0.04)	−0.01 (−0.09 to 0.07)	−2.73 (−9.30 to 3.84)	−1.23 (−7.93 to 5.46)	1.66 (−0.61 to 3.93)	1.55 (−0.70 to 3.80)
Exacerbations in the past year
0	Ref	Ref	Ref	Ref	Ref	Ref
1	−0.05 (−0.12 to 0.02)	−0.02 (−0.09 to 0.04)	−2.39 (−8.08 to 3.29)	0.11 (−5.62 to 5.84)	1.13 (−0.80 to 3.06)	0.56 (−1.36 to 2.48)
≥2	−0.20 (−0.26 to −0.14)	0.13 (−0.19 to −0.07)	−7.23 (−12.0 to −2.47)	−2.48 (−7.38 to 2.43)	4.15 (2.53 to 5.78)	2.82(1.16 to 4.47)
Chronic bronchitis	−0.13 (−0.18 to −0.07)	−0.08 (−0.14 to −0.03)	−6.39 (−10.8 to −1.99)	−3.73 (−8.32 to 0.86)	4.42 (2.95 to 5.89)	3.67(2.13 to 5.20)
Cardiovascular disease	−0.07 (−0.13 to −0.02)	−0.03 (−0.09 to 0.02)	−1.27 (−5.64 to 3.10)	1.47 (−3.11 to 6.05)	−0.22 (−1.74 to 1.29)	−0.65 (−2.19 to 0.89)
Diabetes	−0.05 (−0.14 to 0.04)	−0.05 (−0.13 to 0.04)	−6.55 (−13.4 to 0.33)	−5.42 (−12.5 to 1.64)	0.03 (−2.37 to 2.43)	−0.08 (−2.45 to 2.29)
Renal impairment	−0.09 (−0.24 to 0.06)	−0.05 (−0.18 to 0.09)	−9.90 (−21.5 to 1.73)	−5.55 (−17.5 to 6.37)	0.53 (−3.38 to 4.43)	0.69 (−3.16 to 4.53)
Musculoskeletal symptoms	−0.14 (−0.21 to −0.08)	−0.07 (−0.13 to −0.01)	−4.14 (−9.12 to 0.85)	−1.61 (−6.77 to 3.56)	2.34 (0.62 to 4.06)	1.02 (−0.71 to 2.76)
Osteoporosis	−0.11 (−0.1 7 to −0.05)	−0.01 (−0.07 to 0.05)	−6.97 (−11.7 to −2.23)	−3.75 (−8.91 to 1.41)	1.55 (−0.11 to 3.20)	−0.41 (−2.14 to 1.32)
Depression	−0.16 (−0.23 to −0.08)	−0.12 (−0.18 to −0.05)	−4.16 (−9.93 to 1.61)	−1.79 (−7.56 to 3.99)	2.91 (0.94 to 4.88)	1.75 (−0.17 to 3.67)

Notes: Unadjusted and adjusted regression coefficients (95% confidence interval) for all explanatory variables included in the models. Numbers in bold denote statistically significant associations. On the basis of the full models (including all explanatory variables), stepwise regression was performed, creating the final models with remaining statistically significant associations reported in Table 2 in the main manuscript.

Abbreviations: BMI, body mass index; CAT, COPD Assessment Test; COPD, chronic obstructive pulmonary disease; EQ-5D, Euroqol-5 dimension; FEV₁% pred, FEV₁ as a percentage of predicted value; VAS, visual analog scale.