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. 2020 May 18;106(19):1495–1502. doi: 10.1136/heartjnl-2019-316118

Table 1.

Demographic, clinical characteristics and sleep study results

Characteristics Sleep apnoea
(n=513)
Non-sleep apnoea
(n=494)
P value
Age, median (IQR), years 62 (56–68) 61 (56–67) 0.23
Male sex, n (%) 442 (86.2) 429 (86.8) 0.75
Ethnicity, n (%) 0.37
 Chinese 338 (65.9) 314 (63.3)
 Malay 93 (19.1) 101 (20.4)
 Indian 50 (9.7) 57 (11.5)
 Others 32 (6.2) 22 (4.5)
Clinical measurements
 Systolic blood pressure, mean (SD), mm Hg 125 (111–138) 125 (110–138) 0.70
 Diastolic blood pressure, mean (SD), mm Hg 70 (63–79) 70 (62–79) 0.35
 Body mass index, mean (SD), kg/m2 25.9 (23.3–28.6) 23.5 (21.8–26.2) <0.0001
 Neck circumference, mean (SD), cm 39 (37–41) 38 (36–40) <0.0001
 Waist circumference, mean (SD), cm 95 (88–102) 90 (84–96) <0.0001
Cardiovascular risk factors, n (%)
 Smoking 139 (27.1) 155 (31.4) 0.23
 Hyperlipidaemia 401 (81.2) 417 (81.3) 0.96
 Hypertension 404 (78.8) 349 (70.6) 0.0030
 Diabetes mellitus 295 (57.5) 278 (56.3) 0.69
 Family history of premature coronary disease 37 (7.2) 43 (8.7) 0.38
Concomitant conditions, n (%)
 Previous myocardial infarction 239 (46.6) 221 (44.7) 0.56
 Previous percutaneous coronary intervention 119 (23.2) 101 (20.4) 0.29
 Previous coronary artery bypass surgery 0 (0.0) 2 (0.4) 0.24*
 Stroke/transient ischaemic attack 61 (11.9) 57 (11.5) 0.86
 Chronic kidney disease† 102 (19.9) 63 (12.8) 0.002
 Chronic kidney disease on dialysis 28 (5.5) 8 (1.6) 0.001*
 Pre-existing atrial fibrillation 24 (4.7) 23 (4.3) 1.00*
 Pacemaker in situ 2 (0.4) 1 (0.2) 1.00*
 Implantable cardioverter defibrillator in situ 3 (0.6) 1 (0.2) 0.63*
Sleep study results
 AHI (events per hour), median (IQR) 30.1 (20.6–44.7) 5.85 (3.0–10.23) <0.0001
 RDI (events per hour), median (IQR) 32.9 (24.3–47.4) 10.4 (6.6–14.4) <0.0001
 ODI (events per hour), median (IQR) 18.1 (11.2–33.6) 2.3 (0.9–4.83) <0.0001
 Sleep duration (hour), median (IQR) 6.40 (5.49–7.30) 6.30 (5.32–7.10) 0.24
 Duration SpO2<90% (min), median (IQR) 4.50 (0.60–19.85) 0.00 (0.00–0.60) <0.0001
 Percentage of sleep SpO2<90% (%), median (IQR) 1.20 (0.20–5.08) 0.00 (0.00–0.10) <0.0001
 Epworth Sleepiness Scale >10, n (%) 69 (13.5) 54 (11.0) 0.23
 High-risk Berlin Questionnaire, n (%) 239 (46.8) 201 (40.9) 0.06

*P values were computed using Fisher’s exact test.

†Serum estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2.

AHI, apnoea-hypopnoea index; ODI, oxygen desaturation index; RDI, respiratory disturbance index; SpO2, arterial oxygen saturation.