Association of Plasma Homocysteine with Self-Reported Sleep Apnea Is Confounded by Age: Results from the National Health and Nutrition Examination Survey 2005-2006

Table 2

Sociodemographic, clinical, and relevant biochemical characteristics of the population included in this study (total 𝑛=4490).

Characteristic	Sleep apnea (𝑛=177)	No sleep apnea (𝑛=4313)	𝑃
Age (yrs); mean(SD)	56.5 (15.2)	48.1 (19.0)	<0.001
Males; n (%)	116 (65.5)	2036 (47.2)	<0.001
Race/ethnicity; n (%)			<0.001
Mexican American	11 (6.2)	899 (20.8)
Other Hispanic	2 (1.1)	136 (3.12)
Non-Hispanic White	120 (67.8)	2144 (49.7)
Non-Hispanic Black	40 (22.6)	962 (22.3)
Others	4 (2.3)	172 (4.0)
Country of birth; n (%)			<0.001
United States	168 (94.9)	3345 (77.6)
Mexico	4 (2.3)	583 (13.5)
Elsewhere	5 (2.8)	385 (8.9)
Education; n (%)			0.039
Less than 9th grade	10 (5.7)	543 (12.6)
9–11th grade	20 (11.3)	670 (15.5)
High school	48 (27.1)	1018 (23.6)
Some college education	53 (29.9)	1228 (28.5)
College graduate	46 (26.0)	849 (19.7)
Refused/do not know	0 (0.0)	5 (0.1)
Marital status; n (%)			0.016
Married	121 (68.4)	2340 (54.3)
Widowed	11 (6.2)	388 (9.0)
Divorced	15 (8.5)	412 (9.6)
Separated	5 (2.8)	130 (3.0)
Never married	14 (7.9)	675 (15.7)
Living with partner	11 (6.2)	365 (8.5)
Refused to answer	0 (0.0)	3 (0.1)
Poverty income ratio; mean (SD)	2.84 (1.64)	2.68 (1.59)	0.194
Body mass index (Kg/m^2); mean (SD)	34.90 (0.62)	28.55 (0.10)	<0.001
Ever smoking; n (%)	101 (57.06)	2026 (46.97)	0.008
Ever alcohol use; n (%)	41 (23.16)	682 (15.81)	0.009
Plasma homocysteine (μmol/L); mean (SD)	9.49 (3.75)	8.44 (4.62)	0.003
RBC folate (ng/mL); mean (SD)	326.7 (180.4)	297.0 (135.4)	0.005
Plasma folate (ng/mL); mean (SD)	14.65 (15.4)	13.8 (9.5)	0.255