Excessive Daytime Sleepiness and Cardiovascular Mortality in US Adults: A NHANES 2005–2008 Follow-Up Study

Figures & data

Table 1 Baseline Characteristics by Baseline Daytime Sleepiness Category Among 10,330 Adults in the NHANES 2005–2008^a

Characteristics	Degree of Daytime Sleepiness ^e			P-value
	No Daytime Sleepiness	Mild Daytime Sleepiness	EDS
Participants	3878	4663	1789
Age, years ^b	49.6 (48.0, 51.2)	46.0 (45.0,47.0)	45.6 (44.0, 47.2)	<0.0001
Age group ^b				<0.0001
≤65 years	2691 (77.8)	3669 (87.0)	1390 (84.3)
>65 years	1187 (22.2)	994 (13.0)	399 (15.7)
Sex ^b				0.001
Female	1692 (47.1)	2349 (51.0)	1009 (57.2)
Male	2186 (52.9)	2314 (49.0)	780 (42.8)
Race ^b				<0.0001
Hispanic	1249 (18.1)	1038 (10.0)	360 (8.6)
Non-Hispanic Black	921 (12.3)	982 (10.4)	354 (10.6)
Non-Hispanic White	1562 (64.0)	2454 (73.9)	996 (75.0)
Other	146 (5.6)	189 (5.8)	79 (5.6)
BMI, kg/m^2	28.2 (27.8, 28.5)	28.5 (28.1, 29.0)	29.2 (28.6, 29.8)	0.005
Annual family income ^b				<0.0001
<20,000	980 (18.5)	1010 (13.8)	530 (22.2)
≥20,000	2708 (81.5)	3521 (86.2)	1188 (77.8)
Education ^b				0.002
Less than college	2357 (47.9)	2263 (39.7)	987 (48.5)
College or above	1516 (52.1)	2,96 (60.3)	799 (51.5)
Smoking status ^b				<0.0001
Current	783 (17.8)	1066 (24.0)	482 (31.4)
Former	1017 (27.6)	1158 (23.8)	453 (23.8)
Never	2078 (54.6)	2430 (52.2)	853 (44.8)
Alcohol consumption ^b				0.0001
Yes	2291 (71.5)	3052 (78.3)	1074 (70.6)
No	1051 (28.5)	1166 (21.7)	508 (29.4)
Hypertension ^c	1652 (35.0)	1938 (35.8)	807 (40.1)	0.16
Diabetes ^c	691 (12.7)	655 (10.9)	349 (14.5)	0.06
Hypercholesterolemia ^c	1394 (36.5)	1779 (36.9)	739 (37.6)	0.91
Cardiovascular disease ^b	435 (8.9)	522 (8.4)	311 (12.3)	0.01
Chronic obstructive pulmonary disease ^b	209 (5.2)	358 (6.5)	246 (13.7)	<0.0001
Cancer ^b	373 (9.5)	406 (8.0)	200 (9.8)	0.49
Chronic kidney disease ^c	432 (7.9)	433 (6.3)	231 (8.8)	0.09
Depression ^d	110 (2.1)	269 (4.3)	360 (18.4)	<0.0001
Sleep disorders ^b	162 (4.0)	318 (6.9)	312 (15.4)	<0.0001
Sleep apnea	41 (2.6)	83 (4.5)	65 (8.8)
Insomnia	3 (0.2)	13 (0.6)	11 (1.5)
Restless legs	2 (0.1)	4 (0.2)	5 (0.6)
Other	116 (1.1)	218 (1.6)	231 (4.5)
Sleep duration, ^b hours	7.1 (7.0, 7.2)	6.9 (6.8, 7.0)	6.3 (6.1, 6.4)	<0.0001
Sleep duration ^b				<0.0001
≤6	1166 (29.0)	1864 (36.9)	1055 (55.2)
7–8	2335 (62.3)	2498 (56.8)	617 (39.3)
≥9	373 (8.6)	299 (6.3)	114 (5.5)

Notes: ^aAll estimates accounted for complex survey design. Data were presented as number (%) or means (95% CI). ^b Variables were acquired through corresponding questionnaires. Sleep disorders included self-reported sleep apnea, insomnia, restless legs and other sleep disorders. ^c Variables were ascertained by both questionnaires and lab tests /examination. ^d Depression was assessed using the Patient Health Questionnaire 9-item survey with a score ≥10 indicative of major depression. ^e No daytime sleepiness was defined as never feeling overly sleepy during the day for last month; Mild daytime sleepiness was defined as rarely or sometimes (1 to 4 times a month) feeling overly sleepy during the day; Excessive daytime sleepiness was defined as often or almost always (5 to 30 times a month) feeling overly sleepy during the day.

Abbreviations: BMI, body mass index. EDS, excessive daytime sleepiness.

Table 2 Hazard Ratios (95% CIs) of Cardiovascular Mortality with Daytime Sleepiness in NHANES 2005–2008^a

Variables ^b	No. (%) of Events	Model 1	Model 2	Model 3
No DS	111 (1.4)	Reference	Reference	Reference
Mild DS	96 (1.2)	1.23 (0.76, 1.98)	1.50 (0.83, 2.69)	1.37 (0.73, 2.58)
EDS	55 (2.3)	2.53 (1.27, 5.03)	2.85 (1.33, 6.09)	2.55 (1.23, 5.27)

Notes: ^aModel estimates were adjusted for the complex sampling design. Model 1 was adjusted for age, sex, race, education, and income. Model 2 was further adjusted for alcohol, smoking, body mass index, hypertension, hypercholesterolemia, cardiovascular disease, diabetes mellitus, depression, chronic obstructive pulmonary disease, chronic kidney disease and cancer. Model 3 was adjusted for sleep disorders and sleep duration in addition to the variables in model 2. ^bNo daytime sleepiness was defined as never feeling overly sleepy during the day for last month; Mild daytime sleepiness was defined as rarely or sometimes (1 to 4 times a month) feeling overly sleepy during the day; Excessive daytime sleepiness was defined as often or almost always (5 to 30 times a month) feeling overly sleepy during the day.

Abbreviations: DS, daytime sleepiness; EDS, excessive daytime sleepiness.

Figure 1 Cox cumulative hazard function for cardiovascular mortality by degree of daytime sleepiness. The model was fully adjusted for socioeconomic factors, cardiovascular risk factors, comorbidities, sleep duration and sleep disorders. HR, hazard ratio; No daytime sleepiness was defined as never feeling overly sleepy during the day for last month; Mild daytime sleepiness was defined as rarely or sometimes (1 to 4 times a month) feeling overly sleepy during the day; Excessive daytime sleepiness was defined as often or almost always (5 to 30 times a month) feeling overly sleepy during the day.

Abbreviation: CI, confidence interval.

Figure 2 Associations between EDS and risk of cardiovascular mortality stratified by sex, age and body mass index in fully adjusted model.

Abbreviations: BMI, body mass index; CI, confidence interval; CVD, cardiovascular disease; EDS, excessive daytime sleepiness; HR, hazard ratio.

Table 3 Sensitivity Analyses of Association Between Daytime Sleepiness and Cardiovascular Mortality in Weighted and Fully Adjusted Multivariable Analysis (HR [95% CI])

Variables^a	Exclusion of Deaths Within 6-Months	Without CVD at Baseline	With CVD at Baseline
No. of events/total	251/10271	141/9062	121/1268
No DS	Reference	Reference	Reference
Mild DS	1.11 (0.60, 2.04)	1.56 (0.77, 3.15)	1.09 (0.39, 3.05)
EDS	2.45 (1.20, 5.00)	2.34 (0.82, 6.67)	2.57 (0.81, 8.15)

Notes: ^aNo daytime sleepiness was defined as never feeling overly sleepy during the day for last month; Mild daytime sleepiness was defined as rarely or sometimes (1 to 4 times a month) feeling overly sleepy during the day; Excessive daytime sleepiness was defined as often or almost always (5 to 30 times a month) feeling overly sleepy during the day.

Abbreviations: CVD, cardiovascular diseases; DS, daytime sleepiness; EDS, excessive daytime sleepiness.