Factors affecting the relationship between psychological status and quality of life in COPD patients

Table 3 Adjusted association between psychological status and health-related quality of life (SGRQ).

	Total		Activity		Impact		Symptoms
	β (95% CI)*	p value	β (95% CI)*	p value	β (95% CI)*	p value	β (95% CI)*	p value
Psychological factors:
Anxiety only	6.02 (2.88, 9.16)	< 0.001	4.23 (-0.07, 8.52)	0.054	8.71 (4.93, 12.49)	< 0.001	4.07 (-0.42, 8.56)	0.076
Depression only	6.29 (0.55, 12.03)	0.032	11.34 (2.92, 19.77)	0.008	5.90 (-1.03, 12.82)	0.095	4.25 (-3.85, 12.34)	0.303
Anxiety and depression	17.06 (12.50, 21.62)	< 0.001	17.73 (11.24, 24.22)	< 0.001	18.35 (12.79, 23.91)	< 0.001	11.49 (5.36, 17.62)	< 0.001
Gender: females	-	-	-7.84 (-14.67, -1.01)	0.025	-	-	-	-
Working status: current workers	-	-	-	-	-	-	8.03 (3.43, 12.64)	0.001
ATS/ERS severity stages:
Mild	reference		reference		reference
Moderate	5.25 (-0.09, 10.58)	0.054	5.72 (-1.58, 13.01)	0.124	7.34 (0.91, 13.77)	0.025	-	-
Severe	11.25 (5.73, 16.76)	< 0.001	14.49 (6.89, 22.09)	< 0.001	12.93 (6.28, 19.57)	< 0.001
Very severe	16.84 (9.78, 23.90)	< 0.001	18.25 (8.35, 28.14)	< 0.001	18.51 (9.92, 27.10)	< 0.001
6MWD (m)	-	-	-0.02 (-0.04, -0.00)	0.033	-	-	-	-
Dyspnea (score from 0 to 5)	6.87 (5.90, 7.85)	< 0.001	9.87 (8.46, 11.28)	< 0.001	5.54 (4.37, 6.72)	< 0.001	4.36 (3.09, 5.64)	< 0.001
BMI: <20 (kg/m ² )	-	-	-	-	9.93 (0.90, 18.96)	0.031	-	-
Barthel Index: dependent ^†	6.67 (2.18, 11.15)	0.003	10.73 (3.14, 18.31)	0.006	5.76 (0.35, 11.17)	0.037	-	-
Charlson Comorbidities: ≥2	3.70 (1.26, 6.15)	0.003	4.94 (1.53, 8.35)	0.005	3.91 (0.96, 6.86)	0.010	-	-
Adjusted R ²	0.61		0.65		0.49		0.20

CI: confidence interval
* Each column is a single multivariate lineal regression model including as covariates the variables that show a coefficient in each column. Beta-coefficients are expressed in points of the SGRQ score per (i) each unit of the continuous covariates in the model, or (ii) a change with respect to reference category in categorical covariates.
† Dependent defined as Barthel Index < 100
Age, socioeconomic status, level of education, marital status, smoking status, DLco, RV/TLC, PaO₂ and PaCO₂, were tested as potential confounders and finally not included because they were not independently related to the outcome, nor modified estimates for the remaining variables.

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