Anemia Severely Reduces Health-Related Quality of Life in COPD Patients Receiving Long-Term Home Non-Invasive Ventilation

Figures & data

Figure 1 Flow diagram of subject recruitment and data availability.

Abbreviations: N, number; OSAS, obstructive sleep apnea syndrome; OHS, obesity hypoventilation syndrome; NMD, neuromuscular diseases; SRI, Severe Respiratory Insufficiency Questionnaire.

Table 1 Patient Characteristics, Exacerbation History, Hemoglobin Levels, Number of Anemic Patients, and SRI Scores (n=128, if Not Otherwise Stated)

	Mean ± SD
Age [years]	65.6 ± 8.1
Female/male [%]	46.1/53.9
Body mass index [kg/m^2]	27.4 ± 8.3
*Smoking [pack years]	56.0 ± 25.9
Duration of NIV [years]	1.7 ± 1.8
Exacerbation history (preceding 12 months) (N=124)
≤1 exacerbation/≥2 exacerbations [%]	56.5/43.5
Updated Charlson Comorbidity Index (N=127)	2.3 ± 1.9
Hemoglobin level [g/dl]	13.1 ± 1.9
Anemia [%]	32.8
- Male [% of all anemic patients]	64.3
- Female [% of all anemic patients]	35.7
SRI summary scale	50.3 ± 17.5
SRI subscale scores
- Respiratory complaints	48.6 ± 20.7
- Physical functioning	34.3 ± 23.2
- Attendant symptoms and sleep	56.2 ± 23.0
- Social relationships	66.8 ± 21.5
- Anxiety	44.3 ± 25.8
- Psychological well-being	53.8 ± 20.5
- Social functioning	47.8 ± 21.7

Note: *76% former smokers and 24% current smokers.

Abbreviations: SD, standard deviation; NIV, non-invasive ventilation; SRI, Severe Respiratory Insufficiency Questionnaire.

Table 2 Multiple Linear Regression Analysis, with the SRI Summary Scale Score as the Dependent Variable (N=128)

Independent Variables and Confounders	Regression Coefficient 95% CI (Lower/Upper Limit)	P-value
Age (for each additional year)	0.133; −0.235/0.502	0.475
Sex (women vs men)	0.274; −5.756/6.304	0.928
BMI (for each additional index-point)	−0.209; −0.581/0.164	0.270
Duration of NIV (for each additional month)	−0.076; −0.213/0.061	0.273
*Exacerbation history (positive vs negative)	−9.899; −15.455/-4.344	0.001
Updated Charlson Comorbidity Index (for each additional index-point)	0.562; −1.012/2.136	0.481
*Anemia (positive vs negative)	−8.438; −14.901/-1.975	0.011

Note: *Dichotomized categories as defined in the text.

Abbreviations: CI, confidence interval; NIV, non-invasive ventilation; SRI, Severe Respiratory Insufficiency Questionnaire; BMI, body mass index.

Figure 2 Regression coefficients for anemia and exacerbation history in relation to SRI scores.

Notes: Colored bars (grey for anemia, black for exacerbation history) indicate statistical significance (P <0.05); white bars indicate non-significance (P >0.05).

Abbreviations: SRI, Severe Respiratory Insufficiency Questionnaire; SS, Summary Scale; RC, Respiratory Complaints; PF, Physical Functioning; AS, Attendant Symptoms and Sleep; SR, Social Relationships; AX, Anxiety; WB, Psychological Well-Being; SF, Social functioning.

Figure 3 95% confidence intervals for the regression coefficient of SRI scores used in the multiple linear regression analysis for exacerbation history.

Notes: Black bars (exacerbation history) indicate statistical significance (P <0.05); white bars indicate non-significance (P >0.05); vertical line within each bar represents the regression coefficient.

Abbreviations: SRI, Severe Respiratory Insufficiency Questionnaire; SS, Summary Scale; RC, Respiratory Complaints; PF, Physical Functioning; AS, Attendant Symptoms and Sleep; SR, Social Relationships; AX, Anxiety; WB, Psychological Well-Being; SF, Social functioning.

Figure 4 95% confidence intervals for the regression coefficient of SRI scores used in multiple linear regression analysis for anemia.

Notes: Grey bars (anemia) indicate statistical significance (P <0.05); white bars indicate non-significance (P >0.05); vertical line within each bar represents the regression coefficient.

Abbreviations: SRI, Severe Respiratory Insufficiency Questionnaire; SS, Summary Scale; RC, Respiratory Complaints; PF, Physical Functioning; AS, Attendant Symptoms and Sleep; SR, Social Relationships; AX, Anxiety; WB, Psychological Well-Being; SF, Social functioning.