Study population characteristics.
A total of 1974 individuals (i.e. 1289 hypertensive and 685 normotensives) were enrolled in this study. Table 1 displays the sociodemographic and clinical characteristics of study participants. The mean age was 53.4 years and 63.8% of participants were aged 60 years or less. Females constituted the large majority (60.4%) of participants. 54.0% of participants had attained primary school as their highest level of education and 67.9% were in marriage. Over 80% of participants dwelled in urban areas, 63.3% had a regular income generating activity and 26.4% worked at least 8 hours a day. Over one-sixth (15.9%) had a positive smoking history and 10% were current alcohol consumers. Nearly three quarters (74.1%) of participants had excess body weight, 11.6% had diabetes, 8.0% had asthma and 18.6% had history of recurrent nasal congestion. Positive family history of snoring was reported by 43.1% of participants and 36.9% had a personal history of snoring. Surprisingly, none of the participants in this study was aware of OSA and its potential in causing or worsening CVDs and other chronic conditions.
Table 1
Sociodemographic characteristics of study participants by hypertension status.
Characteristic
|
ALL
N = 1974
|
Hypertensive
n = 1289
|
Normotensive
n = 685
|
p-value
|
Age (Mean, SD)
Range
Age group
>60
≤60
|
53.4 (15.0)
18–98
714 (36.2%)
1260 (63.8%)
|
59.8 (11.8)
18–98
653 (50.7%)
636 (49.3%)
|
41.3 (13.0)
18–83
61 (08.9%)
624 (91.1%)
|
< 0.001
< 0.001
|
Sex
Male
Female
|
782 (39.6%)
1192 (60.4%)
|
483 (37.5%)
806 (62.5%)
|
299 (43.7%)
386 (56.4%)
|
< 0.01
|
Education
No Formal
Primary
Secondary
University
|
117 (05.9%)
950 (48.1%)
513 (26.0%)
394 (20.0%)
|
100 (07.8%)
643 (49.9%)
318 (24.6%)
228 (17.7%)
|
17 (02.5%)
307 (44.8%)
195 (28.5%)
166 (24.2%)
|
< 0.001
0.03
0.06
< 0.001
|
Marital status
Single
Married
Divorced
Widowed
|
192 (09.7%)
1341 (67.9%)
128 (06.5%)
313 (15.9%)
|
48 (03.7%)
873 (67.7%)
82 (06.4%)
286 (22.2%)
|
144 (21.0%)
468 (68.3%)
46 (06.7%)
27 (04.0%)
|
< 0.001
0.79
0.80
< 0.001
|
Occupation
Jobless
Self-employed
Employed
Retired
Work duration (hours)
Mean (SD)
>8 hours/day
|
371 (18.8%)
888 (45.0%)
362 (18.3%)
353 (17.9%)
6.2 (3.8)
521 (26.4%)
|
253 (19.6%)
487 (37.8%)
219 (17.0%)
330 (25.6%)
5.4 (3.5)
256 (19.9%)
|
118 (17.2%)
401 (58.5%)
143 (20.9%)
23 (03.4%)
7.7 (3.9)
265 (38.7%)
|
0.19
< 0.001
0.03
< 0.001
< 0.001
< 0.001
|
Residence
Urban
Rural
|
1618 (82.0%)
356 (18.0%)
|
1030 (79.9%)
259 (20.1%)
|
588 (85.8%)
97 (14.2%)
|
< 0.01
|
Personal Disease History (% Yes)
Diabetes
Asthma
Stroke
Recurrent nocturnal nasal congestion
|
228 (11.6%)
158 (08.0%)
113 (05.7%)
367 (18.6%)
|
211 (16.4%)
107 (08.3%)
103 (08.0%)
270 (21.0%)
|
17 (02.5%)
51 (07.5%)
10 (01.5%)
97 (14.2%)
|
< 0.001
0.53
< 0.001
< 0.001
|
Smoking status
Ever smoker
Never
|
313 (15.9%)
1661 (84.1%)
|
284 (14.3%)
1105 (85.7%)
|
129 (18.8%)
556 (81.2%)
|
< 0.01
|
Alcohol intake (current)
Yes
No
|
197 (10.0%)
1777 (90.0%)
|
70 (05.4%)
1219 (94.6%)
|
127 (18.5%)
558 (81.5%)
|
< 0.001
|
Body Mass Index (mean, SD)
BMI categories
Underweight
Normal
Overweight
Obese
Waist circumference (mean[cm], SD)
Men > 90cm
Women > 80cm
Neck circumference (mean[cm], SD)
Men > 37cm
Women > 31cm
|
29.1 (6.2)
34 (01.7%)
478 (24.2%)
680 (34.5%)
782 (39.6%)
98.1 (14.0)
486 (62.1%)
1089 (91.4%)
36.8 (3.5)
434 (55.5%)
1095 (91.9%)
|
30.3 (6.3)
11 (0.9%)
225 (17.4%)
447 (34.7%)
606 (47.0%)
101.0 (13.4)
357 (73.9%)
766 (95.0%)
37.2 (3.4)
314 (65.0%)
767 (95.2%)
|
26.9 (5.5)
23 (03.4%)
253 (36.9%)
233 (34.0%)
176 (25.7%)
92.8 (13.4)
129 (43.1%)
323 (83.7%)
35.9 (3.6)
120 (40.1%)
328 (85.0%)
|
< 0.001
< 0.001
< 0.001
0.76
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
< 0.001
|
Family history of snoring
Positive
Negative
Don’t Know
Personal history of snoring
Positive
Negative
Don’t Know
|
851 (43.1%)
982 (49.8%)
141 (07.1%)
729 (36.9%)
1156 (58.6%)
89 (04.5%)
|
566 (43.9%)
617 (47.9%)
106 (08.2%)
564 (43.8%)
659 (51.1%)
66 (05.1%)
|
285 (41.6%)
365 (53.3%)
35 (05.1%)
165 (24.0%)
497 (72.6%)
23 (03.4%)
|
0.33
0.02
0.01
< 0.001
< 0.001
0.08
|
OSA awareness
Yes
No
|
0 (0%)
1974 (100%)
|
0 (0%)
1289 (100%)
|
0 (0%)
685 (100%)
|
1.0
1.0
|
Prevalence and correlates of OSA.
Overall, 624 (31.6%) of all participants were categorized as having high-risk for OSA. Persons with hypertension displayed a higher frequency (42.1%) of OSA compared to their normotensive counterparts (11.8%), p < 0.001. Furthermore, the prevalence of OSA was similar among hypertensives regardless of their BP range i.e. 41.1% in SBP < 140, 43.2% in SBP140-159 and 42.4% in SBP ≥ 160. Moreover, individuals with hypertension had a 6.8% prevalence of EDS compared to 5.6% among controls, p = 0.3, Table 2. During bivariate analyses, participants with high-risk OSA were older (57.9 vs 51.3, p < 0.001) and a positive linear correlation between age and OSA until the age group 60–70 years was observed i.e. <40 years, 13.4%; 41–50 years, 29.0%; 51–60 years, 36.7%; 61–70 years, 42.9%; and > 70 years, 36.3%. Moreover, participants with high-risk for OSA had a higher comorbidity history [hypertension (87.0% vs 55.3%, p < 0.001), diabetes (18.3% vs 8.4%, p < 0.001), stroke (7.2% vs 5.0%, p = 0.05) and recurrent nasal congestion (25.8% vs 15.3%, p < 0.001)], and a higher frequency of known risk factors i.e. positive smoking history (18.3% vs 14.7%, p = 0.04), increased body weight (88.9% vs 67.2%, p < 0.001), increased neck circumference (88.6% vs 72.3%, p < 0.001), post-menopause (83.5% vs 59.8%, p < 0.001), positive family (70.2% vs 30.6%, p < 0.001) and personal history of snoring (99.7% vs 7.9%, p < 0.001), and a higher ESS score (42.8% vs 27.6%, p < 0.001); Table 3. Males and females displayed similar odds of OSA (i.e. 31.7% vs 31.5%, p = 0.9).
Table 2
Prevalence and pattern of EDS by hypertension status.
EDS
|
Frequency (%)
|
p - value
|
Hypertensive
|
Normotensive
|
Unlikely
|
635 (49.3%)
|
373 (54.5%)
|
0.03
|
Average
|
210 (16.3%)
|
116 (16.9%)
|
0.7
|
Excessive situational
|
356 (27.6%)
|
158 (23.1%)
|
0.03
|
Excessively sleepy
|
88 (06.8%)
|
38 (05.6%)
|
0.3
|
Table 3
Sociodemographic and Clinical characteristics comparison by OSA status.
Characteristic
|
High-risk OSA
n = 624
|
Low-risk OSA
n = 1350
|
p - value
|
Age (Mean, SD)
n
<40 yearsβ 442
41–50 338
51–60 480
61–70 480
>70 years 234
|
57.9 (12.3)
59 (13.4%)
98 (29.0%)
176 (36.7%)
206 (42.9%)
85 (36.3%)
|
51.3 (15.7)
|
<0.001
-
< 0.001
< 0.001
< 0.001
< 0.001
|
Female sex
|
376 (60.3%)
|
816 (60.4%)
|
1.0
|
≤ Primary education
|
346 (55.5%)
|
721 (53.4%)
|
0.38
|
Married
|
439 (70.4%)
|
902 (66.8%)
|
0.11
|
Work duration > 8hrs/day
|
135 (21.6%)
|
386 (28.6%)
|
0.001
|
Urban residency
|
505 (80.9%)
|
1113 (82.4%)
|
0.42
|
Comorbidities history
Hypertension
Diabetes
Asthma
Stroke
Recurrent nocturnal nasal congestion
Menopause#
|
543 (87.0%)
114 (18.3%)
48 (07.7%)
45 (07.2%)
161 (25.8%)
314 (83.5%)
|
746 (55.3%)
114 (08.4%)
110 (08.2%)
68 (05.0%)
206 (15.3%)
488 (59.8%)
|
<0.001
<0.001
0.70
0.05
<0.001
<0.001
|
Ever smoker
|
114 (18.3%)
|
199 (14.7%)
|
0.04
|
Current drinker
|
43 (06.9%)
|
154 (11.4%)
|
0.002
|
Measures of obesity
BMI ≥ 25
Neck > 37cm M/31cm F
Waist > 90cm M/80cm F
|
555 (88.9%)
553 (88.6%)
572 (91.7%)
|
907 (67.2%)
976 (72.3%)
1003 (74.3%)
|
<0.001
<0.001
<0.001
|
Snoring history
Positive family
Positive personal
|
438 (70.2%)
622 (99.7%)
|
413 (30.6%)
107 (07.9%)
|
<0.001
<0.001
|
SBP ≥ 140 and/or DBP ≥ 90*
SBP < 140*β 504
SBP 140–159* 424
SBP ≥ 160* 361
|
365 (67.2%)
207 (41.1%)
183 (43.2%)
153 (42.4%)
|
482 (64.6%)
|
0.26
-
0.51
0.70
|
ESS score ≥ 10
|
267 (42.8%)
|
373 (27.6%)
|
<0.001
|
#: assessed in women, n = 1192 ; *: assessed in hypertensives, n = 1289. ; β: reference group |
In a logistic regression model of 16 characteristics, 7 factors i.e. hypertension (OR 5.1, 95% CI 3.2–8.2, p < 0.001), diabetes mellitus (OR 2.2, 95% CI 1.3–3.5, p < 0.01), chronic nasal congestion (OR 1.6, 95% CI 1.1–2.5, p = 0.01), obesity (OR 2.4, 95% CI 1.8–3.3, p < 0.001), increased neck circumference (OR 2.7, 95% CI 1.2–6.4, p = 0.02), family history of snoring (OR 5.5, 95% CI 4.0-7.5, p < 0.001), and working > 8hrs/24hr (OR 0.6, 95% CI 0.4-1.0, p = 0.03) were found to have an independent association for OSA, Table 4. Furthermore, as displayed in Fig. 1, participants with hypertension had superior odds for OSA compared to their normotensive counterparts across all subgroup analyses. For instance, among individuals with BMI ≥ 25 those with hypertension displayed a 4-fold chance of having OSA compared to normotensive persons, OR 4.0, 95% CI 3.0-5.5, p < 0.001. Similarly, among participants with a positive family history of snoring, those with hypertension had a 7-fold likelihood of having OSA compared to their counterparts with negative history of hypertension, OR 7.1, 95%CI 5.1–10.1, p < 0.001. Nevertheless, participants with diabetes displayed similar odds of OSA regardless of their hypertension status, OR 1.9, 95%CI 0.6–6.6, p = 0.21.
Table 4
Logistic regression analyses for factors associated with OSA.
Characteristic
|
Comparative
|
OR
|
95% CI
|
p-value
|
Adj.OR
|
95% CI
|
p-value
|
Age > 60
|
Age ≤ 60
|
1.9
|
1.6–2.3
|
< 0.001
|
1.2
|
0.8–1.7
|
0.32
|
Male
|
Female
|
1.0
|
0.8–1.2
|
0.94
|
-
|
-
|
-
|
Diabetes
|
Diabetes-free
|
2.4
|
1.8–3.2
|
< 0.001
|
2.2
|
1.3–3.5
|
< 0.01
|
Asthmatic
|
Asthma-free
|
0.9
|
0.7–1.3
|
0.73
|
-
|
-
|
-
|
History of stroke
|
Stroke-free
|
1.5
|
1.0-2.2
|
0.05
|
0.8
|
0.4–1.6
|
0.57
|
Chronic nasal congestion
|
No congestion
|
1.9
|
1.5–2.4
|
< 0.001
|
1.6
|
1.1–2.5
|
0.01
|
Ever smoker
|
Never smoker
|
1.3
|
1.0-1.7
|
0.05
|
0.8
|
0.4–1.8
|
0.63
|
BMI ≥ 30
|
BMI < 30
|
3.7
|
3.0-4.5
|
< 0.001
|
2.4
|
1.8–3.3
|
< 0.001
|
Neck > 37cm M/31cm F
|
Normal Neck
|
3.0
|
2.3–3.9
|
< 0.001
|
2.7
|
1.2–6.4
|
0.02
|
Family history of snoring
|
Negative history
|
6.1
|
4.9–7.6
|
< 0.001
|
5.5
|
4.0-7.5
|
< 0.001
|
Uncontrolled BP
|
BP < 140/90
|
0.9
|
0.7–1.1
|
0.33
|
-
|
-
|
-
|
ESS score ≥ 10
|
ESS score < 10
|
2.0
|
1.6–2.4
|
< 0.001
|
1.3
|
0.9–1.8
|
0.12
|
Hypertensive
|
Negative history
|
5.4
|
4.2-7.0
|
< 0.001
|
5.1
|
3.2–8.2
|
< 0.001
|
Alcohol intake
|
Non drinker
|
0.6
|
0.4–0.8
|
0.002
|
1.4
|
0.7–3.1
|
0.34
|
Post-menopausal
|
Pre-menopausal
|
3.4
|
2.5–4.6
|
< 0.001
|
1.2
|
0.8–1.9
|
0.36
|
Works > 8hrs/day
|
works ≤ 8hrs/day
|
0.7
|
0.6–0.9
|
0.001
|
0.6
|
0.4-1.0
|
0.03
|