TABLE 1

Studies examining sleepy and non-sleepy obstructive sleep apnoea patients with respect to demographic, sleep and comorbidity variables

First author [ref.]Demographic and medical dataPolysomnographic data
VariablePatients with EDSPatients without EDSp-valueVariablePatients with EDSPatients without EDSp-value
Kapur [23]Subjects n510615Subjects n510615
Age years63.7±62.065.7±66.0<0.001AHI events·h–131.6±25.628.6±23<0.01
BMI kg·m−232.0±31.130.8±29.9<0.01AHI during REM events·h–139.0±3836.6±34.9<0.05
Respiratory disease %16.89.3<0.001AHI during NREM events·h–129.5±24.326.5±21.4<0.05
Asthma %10.35.5<0.01CT90 %13.0±5.99.5±4.4<0.01
COPD %10.55.1<0.01Mean O2 during REM %91.6±92.592.4±92.9<0.01
Sedative use %11.17.0<0.05Mean O2 during NREM %93.1±93.493.4±93.6<0.05
Habitual snoring %77.162.0<0.001Minimum O2 during REM %78.9±8079.9±81.0NS
Awakening with leg cramps %17.78.1<0.001Minimum O2 during NREM %80.5±8381.5±83.0NS
Not getting enough sleep %35.68.8<0.001TST min341.7±344.5341.9±349.0NS
Trouble falling asleep %17.110.2<0.01Arousal index28.2±25.427.4±25.4NS
Waking up too early %24.011.8<0.001Sleep efficiency %79.5±8279.2±82.7NS
Sleep stage %
Stage 16.5±5.66.5±5.5NS
Stage 260.2±60.960.3±60.6
Stage 3/415.1±12.714.7±13.2NS
REM18.1±18.518.5±18.6NS
Mediano [24]Subjects n2317Subjects n2317
Age years49±650±9NSAHI events·h–162.0±18.060.0±20.0NS
BMI kg·m−233±531±6NSApnoea duration s29±822±70.008
Awake SpO2 %96±196±1NSMinimum O2 saturation87±690±50.01
ESS score17±35±2<0.001Mean O2 saturation69±1279±80.002
MSLT score min4±116±3<0.001Arousal index65±2060±24NS
Sleep latency min11±1618±180.05
Sleep efficiency90±781±130.04
Sleep stage %
Stage 1/281±1271±11NS
Stage 3/46±88±5NS
REM13±614±8NS
Roure [25]Subjects n16491233Subjects n16491233
Age years51±1254±13<0.0001AHI events·h–136±2733±250.005
BMI kg·m−231±631±6NSMinimum O2 saturation78±1279±110.013
Current smoker %28240.03Mean O2 saturation92±592±40.1
Male %8585NSTST min338±67325±650.007
Awake SaO296±196±1NSArousal index37±3133±23<0.0001
ESS score15±37±3<0.0001Sleep latency min21±2728±31<0.0001
Sleep efficiency %79±2272±31<0.0001
Sleep stage %
Stage 1/283±1486±110.007
Stage 3/411±138±100.018
REM5±45±40.9
Oksenberg [26]Subjects n327242Subjects n327242
Age years54.4±10.757.0±10.70.008AHI events·h–167.2±21.657.1±18.30.0001
BMI kg·m−234.3±5.533.0±5.20.009Arousal index35.0±23.024.2±17.60.0001
Male %85.383.5NSMinimum SaO2 during REM %67.5±16.174.3±13.40.0001
Hypertension %46510.033Minimum SaO2 NREM %77.1±10.180.5±7.60.0001
Arousal index65.5±21.358.0±20.50.0001
Sleep latency min8.6±10.112.3±18.90.014
Sleep efficiency83.2±10.082.2±10.5NS
Sleep stage %
Stage 3/410.9±9.014.5±8.40.0001
REM17.2±5.817.1±6.0NS
Montemurro [27]Subjects n3160Subjects n3160
Age years54.7±12.057.5±130.328AHI events·h–146.9±15.256.7±19.90.018
BMI kg·m−231.0±5.833.1±6.10.117Minimum SaO2 %78.5±9.175.5±11.50.208
Male %83750.427Mean SaO2 %94.6±2.193.4±2.50.021
ESS score13±2.25.8±(2.6<0.001TST min295.0±67.5304.2±76.70.578
Arousal index41.4±15.250.6±19.10.022
Sleep latency min12.1±14.115.4±15.60.326
Sleep efficiency %72.7±14.573.5±16.60.827
Sleep stage %
Stage 115.7±10.012.7±7.50.112
Stage 261.2±14.065.1±11.60.161
Stage 311.1±9.99.4±7.80.365
REM12.9±5.712.7±7.30.878
Bravo [28]Subjects n2250Subjects n2250
Age years51.3±1.452.3±2.4NSAHI events·h–153.1±3.948.9±3.3NS
BMI kg·m−233.3±1.030.9±1.4NSMean SaO2 %86.4±1.289.4±1.7NS
Current smoker %42.8%40.9%NS
Hypertension %57.1%68.2%NS
ESS score16.8±0.55.3±0.8<0.001
Serum level of
P-selectin ng·mL−1129.1±7.6114.1±4.8NS
ICAM-1 ng·mL−1312.7±24.8263.0±11.00.075
TNF-α pg·mL−10.82±0.110.89±0.37NS
IL-6 pg·mL−13.02±0.32.44±0.37NS
8-iso-PGF2α pg·mL−1730.5±74.3584.0±66.10.051
Koutsourelakis[29]Subjects n354561Subjects n354561
Age years53.6±12.849.6±14.0<0.001RDI events·h–144.9±33.820.9±22.7<0.001
BMI kg·m−234.0±7.830.2±7.0<0.001Minimum SaO2%75.6±11.182.7±8.6<0.001
Male %75.770.1NSMean SaO2%91.3±4.793.6±4.8<0.001
Current smoker %39.841.2NSTST min261.3±76.6282.3± 73.0<0.001
Alcohol use %20.312.5<0.001Sleep latency min21.2±24.324.4±32.4NS
COPD %17.42.0<0.001Sleep efficiency %88.2±12.989.4±34.5NS
Asthma %4.12.6NSSleep stage %
Stroke %8.20<0.001Stage 15.2±5.84.2±4.7<0.01
Diabetes %21.23.9<0.001Stage 280.3±12.578.5±12.6NS
Depression %15.82.0<0.001Stage 32.4±7.64.0±8.4<0.01
Ischaemic heart disease %26.03.9<0.001REM11.8±8.012.7±7.7NS
Hypertension %47.525.7<0.001
Sun [30]Subjects n3248Subjects n3248
Age years42.97±10.3345.17±12.560.414AHI events·h–160.92±19.2433.68±22.710.001
BMI kg·m−227.94±3.6225.92±4.130.027Minimum SaO2%54.06±21.2273.10±14.970.001
Awake SO2 %93.38±4.3595.92±1.900.001Mean SaO2%90.06±5.5794.56±4.150.001
ESS score16.53±3.795.29±3.150.001TST min474.48±57.60406.23±75.750.001
MSLT score min3.56±1.0414.67±3.020.001Arousal index56.25±23.6428.93±16.950.001
Sleep latency min8.75±9.5021.05±19.800.001
Sleep efficiency %90.40±7.2383.61±12.270.003
Sleep stage %
Stage 133.66±23.2522.70±26.800.026
Stage 244.58±19.0850.78±19.170.160
Stage 310.06±10.1913.68±8.050.081
REM11.69±7.3312.83±5.930.447
Seneviratne [31]Subjects n17025Subjects n17025
Age years44.4±1152.7±8.8<0.005RDI events·h–137.1±24.925.9±18.70.038
Minimum SaO2%71.8±14.977.7±12.60.053
Arousal index34.9±23.532.3±49.70.032
PLM index4.4±16.31.7±5.60.587
Arousals with PLM8.3±23.61.5±5.20.398
Degree of snoring2.4±0.71.9±0.6<0.005
Sleep efficiency %76.0±14.686.7±10.3<0.005
Sleep stage %
Stage 38.7±7.48.9±7.80.950
REM13.0±5.913.1±7.700.802
Wang [32]Subjects n229109Subjects n229109
Age years48.80±12.7053.00±12.300.002AHI events·h–142.00 (5.00–117.4032.40 (5.00–94.80)0.072
BMI kg·m−228.00 (19.40–43.90)27.10 (15.60–40.10)0.090CT90 %14.20 (0–84.12)8.66 (0–97.55)0.047
Male %80720.104Minimum O2 %74.00 (60.00–95.00)79.00 (60.00–95.00)0.095
ESS score13±9–246±0–8<0.001Mean O2 %92.00 (74.00–98.00)93.00 (62.00–97.00)0.019
Bedtime SBP mmHg125.64±14.96125.18±12.870.784ODI38.40 (0.9–161.40)35.10 (4.00–99.20)0.405
Bedtime DBP mmHg82.73±10.5380.07±9.040.019
Morning SBP mmHg131.52±17.12130.22±14.730.505
Morning DBP mmHg88.45±12.3084.59±9.520.002
Bedtime MAP mmHg97.04±10.9495.30±8.820.124
Morning MAP mmHg102.81±12.6199.80±9.480.018
Waking up with dry mouth %66.556.70.060
Barcelò [33]Subjects n2222Subjects n2222
Age years49±650±50.142AHI events·h–152±1948±160.396
BMI kg·m−232±331±40.230Minimum O2 %69±1281±80.010
Current smoker %4840NSMean O2 %86±690±50.040
ESS score16±34±3<0.001Arousal index65±1962±250.732
MSLT score min5±315±3NS
Glucose mg·dL−1115±19103±200.032
HDLc mg·dL−146±1056±110.002
HOMA index4.3±2.42.3±1.8<0.001
Insulin mU·mL−115.2±7.68.6±4.8<0.001
Nena [34]Subjects n2525Subjects n2525
Age years43.2±9.546.3±10.50.269AHI events·h–153.1±16.350.1± 18.30.550
BMI kg·m−237.1±6.334.8±6.50.218CT90 %35±25.123.3±160.055
Male %88841.000Minimum O2 %77.4±6.177.8±8.10.845
ESS score16.4±3.76.2±2.9<0.001Mean O2 %88.8±4.390.4±1.60.079
Glucose mg·dL−1102.9±16.994.1±13.10.045ODI56.4±18.748.7±20.50.170
HOMA index5.1±4.33±1.60.027
Insulin μIU·mL−119.7±14.311.5±5.60.012
Huang [35]Subjects n11956Subjects n11956
Age years44.2±10.442.8±12.20.438AHI events·h–157.9 (43.8–73.0)56.1 (44.9–65.2)0.336
BMI kg·m−227.95±4.126.4±4.90.032Min O2 %71.0 (60.0–82.0)80.0 (65.00–86.0)0.019
Current smoker %39.537.50.869Mean O2 %92.0 (88.0–95.0)95.0 (92.75–96.0)<0.001
ESS score15.4±3.86.6±2.2<0.001ODI27.6 (12.1–50.0)42.9 (16.1–61.9)0.071
Central obesity89.969.6<0.001
Hypertriglyceridemia %77.314.3<0.001
Metabolic syndrome %78.228.6<0.001
Metabolic score3.2±0.91.9±1.1<0.001

Data are presented as mean±sd or median (interquartile range), unless otherwise stated. EDS: excessive daytime sleepiness; BMI: body mass index; ESS: Epworth sleepiness scale; MSLT: multiple sleep latency test; SaO2: arterial oxygen saturation; SpO2; arterial oxygen saturation measured by pulse oximetry; RDI: respiratory disturbance index; ICAM: intercellular adhesion molecule; TNF: tumour necrosis factor; IGF-1: insulin-like growth factor I; IL: interleukin; PGF2α: prostaglandin F2α; SBP: systolic blood pressure; DBP: diastolic blood pressure; MAP: mean arterial pressure; HDLc: high-density lipoprotein cholesterol; HOMA: homeostasis model assessment; AHI: apnoea–hypoapnoea index; REM : rapid eye movement; NREM : non-rapid eye movement; CT90: percentage of sleep time spent <90% oxygen saturation; TST: total sleep time; PLM: periodic leg movement; ODI: oxygen desaturation index; ns: nonsignificant.