Obstructive sleep apnea, COPD, the overlap syndrome, and mortality: results from the 2005–2008 National Health and Nutrition Examination Survey

Figures & data

Table 1 Subject characteristics (unweighted n=10,388, weighted n=210,916,313)

Characteristics	Total (n=10,388)	Neither COPD nor OSA (n=9,237)	OSA alone (n=366)	COPD alone (n=695)	OSA/COPD overlap (n=90)	P-value
Demographic and socioeconomic status
Age (year)	46.6±0.4	45.8±0.4	52.7±0.8	53.9±0.7	55.8±1.5	<0.001*
20–39	3,664 (37.8)	3,474 (40.3)	119 (20.3)	63 (16.1)	8 (9.9)
40–59	3,235 (38.9)	2,827 (38.1)	225 (41.0)	149 (53.2)	34 (46.4)
60–79	2,755 (18.9)	2,305 (17.4)	271 (31.6)	136 (27.6)	43 (40.6)
80+	734 (4.4)	631 (4.3)	80 (7.0)	18 (3.0)	5 (3.1)
Gender						<0.001*
Female	5,354 (51.9)	4,788 (51.9)	121 (31.4)	405 (63.1)	40 (50.6)
Male	5,034 (48.1)	4,449 (48.1)	245 (68.6)	290 (36.9)	50 (49.4)
Race						<0.001*
Non-Hispanic White	5,007 (70.6)	4,278 (69.5)	224 (80.9)	455 (80.6)	50 (71.2)
Non-Hispanic Black	2,247 (11.3)	2,029 (11.6)	80 (9.4)	112 (7.9)	26 (15.5)
Mexican American	1,936 (8.2)	1,841 (8.8)	35 (3.9)	54 (2.9)	6 (2.5)
Other Hispanic	777 (4.1)	707 (4.3)	18 (3.3)	48 (3.0)	4 (1.5)
Other race	421 (5.7)	382 (5.8)	9 (2.6)	26 (5.5)	4 (9.3)
Poverty income ratio						<0.001*
>2	5,228 (63.0)	4,688 (63.5)	217 (70.6)	280 (52.2)	43 (55.9)
1–2	2,579 (19.5)	2,261 (19.2)	78 (15.4)	220 (25.9)	20 (20.1)
<1	1,843 (11.8)	1,624 (11.6)	47 (8.6)	150 (15.6)	22 (18.1)
Education						<0.001*
Ever attend college	4,780 (55.6)	4,246 (55.8)	200 (61.4)	287 (48.5)	47 (61.7)
Never attend college	5,595 (44.3)	4,980 (44.1)	166 (38.6)	406 (51.3)	43 (38.3)
Lifestyles and behaviors
Smoking						<0.001*
Nonsmoker	5,488 (52.2)	5,078 (53.9)	182 (51.7)	205 (31.9)	23 (30.1)
Former	2,605 (24.4)	2,195 (23.5)	121 (30.1)	242 (30.9)	47 (48.6)
Current	2,286 (23.3)	1,955 (22.5)	63 (18.1)	248 (37.3)	20 (21.4)
Alcohol consuming						<0.001*
Lifetime abstainer	1,381 (10.6)	1,252 (10.7)	39 (9.9)	80 (9.8)	10 (12.2)
Moderate drinker	5,715 (54.0)	4,956 (52.6)	235 (62.8)	460 (65.9)	64 (69.6)
Heavy drinker	2,399 (27.4)	2,201 (28.3)	70 (21.2)	119 (19.6)	9 (14.2)
Physical activity (MET min/week)						<0.001*
≥600	4,987 (53.4)	4,513 (54.5)	167 (49.9)	279 (42.9)	28 (33.5)
<600	3,522 (30.2)	3,071 (29.6)	129 (30.7)	280 (35.9)	42 (37.6)
Serum vitamin D						0.105
Normal	1,833 (22.6)	1,624 (22.9)	55 (18.3)	143 (22.5)	11 (10.3)
Insufficiency	3,638 (38.3)	3,237 (38.2)	140 (42.8)	233 (36.0)	28 (42.8)
Deficiency	3,542 (26.9)	3,126 (26.2)	140 (33.1)	241 (31.0)	35 (33.9)
Comorbidities
Obesity						<0.001*
Underweight/normal	3,029 (32.0)	2,788 (33.5)	27 (8.6)	210 (29.4)	4 (3.8)
Overweight	3,509 (33.1)	3,210 (33.8)	72 (22.4)	207 (31.1)	20 (22.8)
Obese	3,664 (33.4)	3,086 (31.4)	253 (66.5)	263 (38.0)	62 (69.7)
Cancer history						<0.001*
No	9,441 (91.3)	8,471 (92.2)	318 (85.8)	584 (83.9)	68 (74.0)
Yes	934 (8.6)	753 (7.6)	48 (14.2)	111 (16.1)	22 (26.0)
Cardiovascular disease						<0.001*
No	9,200 (91.4)	8,378 (93.2)	272 (80.9)	507 (78.2)	43 (53.5)
Yes	1,188 (8.6)	859 (6.8)	94 (19.1)	188 (21.8)	47 (46.5)
Diabetes mellitus						<0.001*
No/borderline	9,187 (91.8)	8,275 (92.7)	277 (79.5)	583 (89.7)	52 (65.7)
Yes	1,193 (8.1)	954 (7.2)	89 (20.5)	112 (10.3)	38 (34.3)
Hypertension						<0.001*
No	6,859 (69.8)	6,313 (71.9)	150 (46.6)	370 (58.8)	26 (38.3)
Yes	3,513 (30.0)	2,911 (28.0)	215 (53.2)	324 (41.1)	63 (60.6)
Dyslipidemia						0.001*
No	5,345 (53.9)	4,830 (54.7)	163 (46.5)	314 (47.7)	38 (42.0)
Yes	4,800 (44.0)	4,172 (42.9)	201 (53.3)	375 (51.6)	52 (58.0)
eGFR (mL/min/1.73 m^2)						<0.001*
≥60	8,600 (85.3)	7,705 (85.7)	299 (86.4)	531 (80.1)	65 (73.7)
<60	1,089 (8.8)	894 (8.1)	51 (10.9)	128 (15.7)	16 (18.0)
Overall mortality						<0.001*
Assumed alive	9,698 (95.5)	8,704 (96.1)	340 (94.6)	585 (88.7)	69 (79.7)
Assumed deceased	690 (4.5)	533 (3.9)	26 (5.4)	110 (11.3)	21 (20.3)

Notes: Categorical variables were shown unweighted counts (weighted %). Chi-square test was conducted to determine differences in categorical variables.

* Significant difference between groups, P-value <0.05.

Abbreviations: eGFR, estimated glomerular filtration rate; MET, metabolic equivalent of task; OSA, obstructive sleep apnea.

Table 2 Cox regression analyses to determine the factors associated with overall mortality

Variable	Univariate		Multivariate
	HR (95% CI)	P-value	aHR (95% CI)	P-value
Disease entity
OSA alone vs neither COPD nor OSA	1.5 (0.9–2.3)	0.113	1.1 (0.7–1.8)	0.566
COPD alone vs neither COPD nor OSA	3.1 (2.4–4.0)	<0.001*	1.5 (1.2–2.0)	0.001*
OSA/COPD overlap vs neither COPD nor OSA	5.8 (3.2–10.8)	<0.001*	2.4 (1.3–4.3)	0.007*
OSA/COPD overlap vs COPD alone	1.9 (1.1–3.2)	0.018*	1.5 (0.8–2.8)	0.160
Demographic and socioeconomic status
Age (years)
20–39	Reference		Reference
40–59	3.6 (2.1–6.3)	<0.001*	2.9 (1.7–5.1)	<0.001*
60–79	16.6 (10.3–26.9)	<0.001*	9.1 (5.5–14.9)	<0.001*
80+	74.4 (47.2–117.3)	<0.001*	32.0 (18.8–54.3)	<0.001*
Gender
Female	Reference
Male	1.1 (0.9–1.3)	0.407
Race
Non-Hispanic White	Reference		Reference
Non-Hispanic Black	1.0 (0.8–1.2)	0.935	1.0 (0.8–1.3)	0.708
Mexican American	0.5 (0.3–0.6)	<0.001*	0.8 (0.6–1.1)	0.246
Other Hispanic	0.4 (0.2–0.8)	0.016*	0.6 (0.3–1.3)	0.214
Other race	0.4 (0.2–0.9)	0.038*	0.7 (0.3–1.5)	0.338
Poverty income ratio
>2	Reference		Reference
1–2	2.4 (1.9–3.1)	<0.001*	1.3 (1.0–1.7)	0.040*
<1	1.8 (1.3–2.5)	0.002*	1.3 (0.9–1.9)	0.120
Education
Ever attend college	Reference		Reference
Never attend college	2.2 (1.7–2.8)	<0.001*	1.2 (0.9–1.5)	0.172
Lifestyles and behaviors
Smoking
Nonsmoker	Reference		Reference
Former	2.0 (1.6–2.5)	<0.001*	1.3 (1.0–1.8)	0.052
Current	1.2 (0.9–1.7)	0.177	2.0 (1.4–3.0)	0.001*
Alcohol consuming
Lifetime abstainer	Reference		Reference
Moderate drinker	0.7 (0.5–1.0)	0.103	0.9 (0.7–1.3)	0.673
Heavy drinker	0.3 (0.2–0.4)	<0.001*	0.8 (0.6–1.2)	0.291
Physical activity (MET min/week)
≥600	Reference		Reference
<600	2.5 (1.9–3.4)	<0.001*	1.3 (1.0–1.8)	0.097
Serum vitamin D
Normal	Reference		Reference
Insufficiency	1.2 (0.9–1.5)	0.238	1.1 (0.8–1.4)	0.595
Deficiency	1.8 (1.3–2.6)	0.001*	1.5 (1.1–2.1)	0.011*
Comorbidities
Obesity
Underweight/normal	Reference
Overweight	0.9 (0.7–1.1)	0.276
Obese	0.8 (0.5–1.1)	0.120
Cancer history
No	Reference		Reference
Yes	4.2 (3.4–5.1)	<0.001*	1.6 (1.3–1.9)	<0.001*
Cardiovascular disease
No	Reference		Reference
Yes	7.9 (6.3–9.9)	<0.001*	1.9 (1.5–2.4)	<0.001*
Diabetes mellitus
No/borderline	Reference		Reference
Yes	3.9 (3.1–4.8)	<0.001*	1.6 (1.2–2.1)	0.002*
Hypertension
No	Reference		Reference
Yes	3.1 (2.4–4.0)	<0.001*	1.0 (0.8–1.3)	0.744
Dyslipidemia
No	Reference
Yes	1.1 (0.9–1.3)	0.451
eGFR (mL/min/1.73 m^2)
≥60	Reference		Reference
<60	6.6 (5.5–8.0)	<0.001*	1.4 (1.1–1.9)	0.006*

Note:

* Statistically significant, P-value <0.05.

Abbreviations: aHR, adjusted hazard ratio; CI, confidence interval; eGFR, estimated glomerular filtration rate; HR, hazard ratio; MET, metabolic equivalent of task; OSA, obstructive sleep apnea.

Figure 1 The cumulative survival distribution of disease entity.