Predictive factors warrant screening for obstructive sleep apnea in COPD: a Taiwan National Survey

Figures & data

Figure 1 Subject flow for the pooled COPD population with risk of obstructive sleep apnea symptoms.

Abbreviation: OSA, obstructive sleep apnea.

Table 1 Demographics of COPD cohort and comparison by risk of OSA symptoms status

Categories	Subject data values and proportions (%)			P-value (with risk of OSA symptoms vs without)
	COPD cohorta	OSA symptoms risk status
		With	Without
	292 (100)	86 (29.5)	206 (70.5)
Median age (years)	52.9	53.0	52.9	0.976b
1st–3rd quartile (IQR)	44.9–66.2 (17.3)	44.8–62.0 (17.2)	45.0–62.3 (17.3)
Age group (years)				0.842c
40–45	79 (27.1)	27 (31.4)	52 (25.2)
46–50	50 (17.1)	12 (14.0)	38 (18.4)
51–55	37 (12.7)	10 (11.6)	27 (13.1)
56–60	45 (15.4)	13 (15.1)	32 (15.5)
61–65	19 (6.5)	7 (8.1)	12 (5.8)
66–70	18 (6.2)	6 (7.0)	12 (5.8)
≥71	44 (15.1)	11 (12.8)	33 (16.0)
Sex				0.728c
Male	234 (80.1)	70 (81.1)	164 (79.6)
Female	58 (19.9)	16 (18.6)	42 (20.4)
Ever-smoker	251 (86.0)	76 (88.4)	175 (85.0)	0.443c
Specified occupationsd	106 (36.3)	32 (37.2)	74 (35.9)	0.835c
Body mass index (kg/m^2)e	24.3±4.19	26.1±5.82	23.5±2.99	<0.001c
Comorbid diseases
Hypertensive or cardiovascular	119 (40.8)	64 (74.4)	55 (26.7)	<0.001c
Stroke	3 (1.0)	2 (2.3)	1 (0.5)	0.208c
Diabetes mellitus	37 (12.7)	20 (23.3)	17 (8.3)	<0.001c
Cancer	10 (3.4)	4 (4.7)	6 (2.9)	0.457c
Tuberculosis	10 (3.4)	1 (1.2)	9 (4.4)	0.290c
None of the above	154 (52.7)	19 (22.1)	135 (65.5)	<0.001c

Notes:

a Excluding 112 for whom data to assess risk of OSA symptoms were unavailable.

b Wilcoxon rank-sum test.

c Chi-square test.

d Specified occupations/workplaces: brick or ceramic factory, gravel pit, mine; textiles; building and decorating; chemical raw plant or dye factory; truck driver; baker; fire-fighter; cook with wood, coal, or briquettes.

e Calculated from self-reported weight and height.

Abbreviations: OSA, obstructive sleep apnea; IQR, interquartile range.

Table 2 Symptomatic differences between COPD cohorts with or without risk of OSA symptoms

Symptoms/disability quantification indices	OSA symptoms risk status		P-valuea
	With	Without
mMRC Breathlessness score	0.9±1.03	0.7±0.94	0.261
CAT score	16.8±7.74	12.7±7.10	<0.001
Severity of cough	2.5±1.46	2.0±1.33	0.022
Amount of chest sputum	2.1±1.48	1.9±1.40	0.266
Degree of chest tightness	1.8±1.38	1.5±1.45	0.186
Breathing difficulty climbing stairs	2.9±1.39	2.3±1.38	<0.001
Restriction of domestic activities	1.3±1.55	0.8±1.38	0.006
Confidence to go out	1.3±1.66	0.8±1.34	0.013
Quality of sleep	2.3±1.80	1.6±1.70	0.002
Daily vitality	2.6±1.39	1.9±1.39	<0.001

Note:

a Independent-sample t-test.

Abbreviations: OSA, obstructive sleep apnea; mMRC, modified Medical Research Council; CAT, COPD Assessment Test.

Table 3 Life quality differences between COPD cohorts with or without risk of OSA symptoms

Life quality metrics	OSA symptoms risk status		P-valuea
	With	Without
Impaired work performance	1.5±1.52	0.8±1.34	0.002
Work days absent due to respiratory symptoms	1.2±4.45	1.1±8.66	0.955
Impaired leisure activities	1.3±1.60	0.5±1.08	<0.001
Impaired social interaction	1.0±1.52	0.5±1.12	0.004

Note:

a Independent-sample t-test.

Abbreviation: OSA, obstructive sleep apnea.

Table 4 Independent predictors for risk of OSA symptomsa in COPD

Risk predictor	Odds ratio	P-value
	(95% confidence interval)
Age	0.944 (0.905–0.983)	0.006
Body mass index	1.173 (1.057–1.302)	0.003
Hypertension or cardiovascular disease	13.704 (5.466–34.359)	<0.001
CAT score	1.134 (1.068–1.204)	<0.001

Notes:

a Stepwise logistic regression using the forward selection method (dependent variables: 0= patients with COPD without risk of OSA symptoms; 1= patients with COPD with risk of OSA symptoms).

Abbreviations: OSA, obstructive sleep apnea; CAT, COPD Assessment Test.