Fatigue Affects Health Status and Predicts Mortality Among Subjects with COPD: Report from the Population-Based OLIN COPD Study

Figures & data

Table 1.  Study population characteristics (n = 1089)

Characteristic	Non-COPD n = 655	COPD n = 434	p Value	Grade I n = 225	Grade II n = 189	Grade III-IV n = 20
Female, n (%)	280 (42.7)	196 (45.2)	0.432	101 (44.9)	86 (45.5)	9 (45.0)
Age (years), mean (SD)	65.0 (10.4)	65.4 (9.3)	0.505	66.2 (9.6)	64.2 (8.9)	68.8 (6.3)
Age (years), range	35–88	35–88		38–88	35–82	57–82
BMI (kg/m^2), mean (SD)	27.5 (4.3)	26.7 (4.2)	0.002	26.1 (3.4)	27.3 (4.6)	27.8 (7.1)
FEV1% predicted, mean (SD)	97.6 (14.0)	80.5 (16.8)	<0.001	92.7 (10.8)	70.2 (7.0)	40.1 (8.5)
FEV1/FVC, mean (SD)	0.76 (0.04)	0.61 (0.08)	<0.001	0.65 (0.04)	0.66 (0.07)	0.44 (0.12)
Non-smokers, n (%)	330 (50.4)	103 (23.7)		67 (29.8)	34 (18.0)	2 (10.0)
Ex-smokers, n (%)	266 (40.6)	214 (49.3)		102 (45.3)	99 (52.4)	13 (65.0)
Current smokers, n (%)	59 (9.0)	117 (27.0)	<0.001	56 (24.9)	56 (29.6)	5 (25.0)
Respiratory symptoms, n (%)	312 (47.6)	320 (73.3)	<0.001	149 (66.2)	152 (80.4)	19 (95.0)
Clinically significant fatigue, n (%)	241 (36.8)	176 (40.8)	0.180	80 (35.6)	82 (43.4)	14 (70.0)
FACIT-Fatigue score, median (IQR)	47.0 (40–50)	46.0 (38–50)	0.189	48.0 (40–50)	45.0 (38–49)	37.0 (24–45)
Heart disease, n (%)	105 (16.0)	69 (15.9)	0.954	30 (13.3)	31 (16.4)	8 (40.0)
Mortality 2007–2012, n (%)	39 (6.0)	31 (7.1)	0.434	10 (4.4)	17 (9.0)	4 (20.0)

p Value for comparing COPD and non-COPD.

Table 2.  SF-36 Physical (PCS) and Mental (MCS) component summary scores in non-COPD, COPD and by severity of COPD (grade I, II and III-IV). COPD subjects are subdivided into; spirometric classified COPD, COPD with reported respiratory symptoms and COPD with reported clinically significant fatigue, respectively

	n	SF-36 PCS Median (IQR)	p Value^1	p Value≤	p Value≥	SF-36 MCS Median (IQR)	p Value^1	p Value
Non-COPD	655	50.1 (42–55)				54.9 (47–58)
Spirometric classified COPD
COPD	434	49.2 (39–54)	0.026			54.4 (48–58)	0.913	0.575≥
Grade I	225	51.6 (44–55)	0.600			54.4 (49–58)
Grade II	189	47.9 (37–52)	<0.001	<0.001		55.2 (47–58)
Grade III-IV	20	33.4 (23–42)	<0.001	<0.001	<0.001	50.8 (39–58)
Respiratory symptoms
COPD	320	46.9 (36–53)	<0.001			53.9 (47–58)	0.491	0.427≥
Grade I	149	48.4 (40–54)	0.238			54.1 (47–58)
Grade II	152	46.9 (36–52)	<0.001	0.018		54.7 (47–58)
Grade III-IV	19	30.3 (23–41)	<0.001	<0.001	<0.001	50.1 (39–58)
Clinically significant fatigue
COPD	176	39.1 (30–47)	<0.001			48.5 (41–54)	<0.001	<0.001≥
Grade I	80	43.5 (32–51)	<0.001			48.2 (42–54)	<0.001
Grade II	82	37.8 (30–47)	<0.001	0.192		48.8 (42–55)	<0.001	0.984≤
Grade III-IV	14	26.4 (21–38)	<0.001	0.008	<0.001	48.0 (36–54)	0.030	0.722≤

¹Mann-Whitney comparing COPD and non-COPD. Mann–Whitney with Bonferroni correction comparing COPD grades and non-COPD.

≤Mann–Whitney with Bonferroni correction comparing by disease severity (grade I and grade II, grade II and grade III-IV).

≥Kruskal–Wallis.

Figure 1. Median SF-36 physical (PCS) and mental (MCS) component summary scores, comparing subjects without and with respiratory symptoms in the groups non-COPD, COPD and by GOLD grades I and II. GOLD, the Global Initiative for Chronic Obstructive Lung Disease.

Figure 2. Median SF-36 physical (PCS) and mental (MCS) component summary scores, comparing subjects without and with clinically significant fatigue in the groups non-COPD, COPD and by GOLD grades I, II and III-IV. *p Value for comparing non-COPD and COPD, p = 0.027. GOLD, the Global Initiative for Chronic Obstructive Lung Disease.

Table 3.  Spearmans’ rho correlations between FACIT-Fatigue scores and SF-36 physical (PCS), mental (MCS) component summary scores, and the MCS-domain Vitality (VT), respectively in non-COPD, COPD, and severity of COPD

		SF-36 PCS and FACIT-F			SF-36 MCS and FACIT-F			Vitality and FACIT-F
	n	Spearman’s	R^2	p Value	Spearman’s	R^2	p Value	Spearman’s	R^2	p Value
With Respiratory symptoms
Non-COPD	312	0.56	0.31	<0.001	0.57	0.32	<0.001	0.78	0.61	<0.001
COPD	318	0.61	0.37	<0.001	0.51	0.26	<0.001	0.77	0.59	<0.001
Grade I	148	0.55	0.30	<0.001	0.48	0.23	<0.001	0.68	0.46	<0.001
Grade II	151	0.60	0.36	<0.001	0.53	0.28	<0.001	0.81	0.66	<0.001
Grade III-IV	19	0.65	0.42	0.002	0.72	0.52	0.001	0.93	0.86	<0.001
Without respiratory symptoms
Non-COPD	343	0.48	0.23	<0.001	0.49	0.24	<0.001	0.71	0.50	<0.001
COPD	113	0.45	0.20	<0.001	0.50	0.25	<0.001	0.72	0.52	<0.001

Table 4.   Multiple logistic regression model analysing risk factors for mortality in separate models for FACIT-Fatigue, SF-36 physical (PCS) and mental (MCS) component summary scores (Models A–C, respectively), adjusting for sex, age, BMI and heart disease, expressed as Odds Ratio (OR) with 95% confidence interval (CI)

		Non-COPD		COPD
		OR	95% CI	OR	95% CI
Model A	Male	2.50	1.12–5.59	1.98	0.86–4.56
	↑­Age^1	1.13	1.08–1.18	1.05	1.00–1.10
	↓FACIT-F^1	1.02	0.98–1.02	1.06	1.02–1.10
Model B	Male	2.49	1.11–5.58	1.98	0.86–4.58
	↑Age^1	1.13	1.08–1.18	1.05	1.00–1.10
	↓SF-36 PCS^1	1.00	0.97–1.04	1.04	1.01–1.08
Model C	Male	2.48	1.11–5.55	2.06	0.88–4.82
	↑Age^1	1.13	1.08–1.18	1.05	1.00–1.10
	↓SF-36 MCS^1	1.00	0.96–1.04	1.06	1.02–1.10

¹Entered as continuous variables.

BMI and heart disease was non-significant in all three Models (A–C).