Table 1

Summary of demographic and outcome variables

DomainVariableOSAS Obese controls p Value*pNP
NMeasureNMeasure
DemographicsAge, years4214.5±1.53714.2±1.50.2880.294
Male, N (%)4231 (73.8)3723 (62.2)0.2670.335
African American, N (%)4231 (73.8)3732 (86.5)0.1620.262
BMI, Z-score422.36±0.36372.24±0.340.1430.216
AHI, N/hour 42 17.2±18.4 37 0.52±0.40 <0.0001 <0.0001
Lymphoid tissue size Tonsil volume, mm3 42 9665±4944 37 7084±2517 0.004 0.017
Adenoid volume, mm3 42 11 442±4747 37 8588±3889 0.005 0.008
ATV, mm3 42 21 107±7749 37 15 672±5712 0.001 0.002
Nasopharyngeal airway size NPAV, mm3 42 2269±1399 37 3233±1275 0.002 0.001
Nasopharyngeal cross-sectional area, mm2 42 478±297 37 723±383 0.002 0.003
Nasopharyngeal minimum area, mm2 42 75±52 37 104±54 0.017 0.009
Upper airway closing pressures Slope of the pressure–flow response (activated) mL/s/cm H2O 42 21.3±20.4 37 11.9±21.1 0.049 0.002
Pcrit (activated), cm H2O§ 42 −11.6±9.4 37 −18.0±9.0 0.003 0.005
Slope of the pressure–flow response (hypotonic), mL/s/cm H2O4223.7±15.03719.6±15.50.2290.068
Pcrit (hypotonic), cm H2 42 −7.4±7.6 37 −14.2±7.7 <0.001 <0.001
Genioglossal electromyogram (EMGgg) EMGgg slope (activated), %/cm H2O 32 −1.67±5.60 23 −10.34±18.15 0.036 0.004
EMGgg slope (hypotonic), %/cm H2O30−1.43±3.3422−1.81±3.500.6910.424
CO2 responseHCVR slope, L/min/mm Hg PETCO2 311.83±0.98242.11±1.150.3320.511
HCVR correlation coefficient310.84±0.10240.84±0.110.9390.820
CO2 response during sleep, %ΔVE 16 28.0±22.8 17 73.1±26.0 <0.0001 <0.001
  • *p Value from χ2 test or t-test comparing values between OSAS and controls.

  • †p Value from non-parametric Wilcoxon or Fisher's exact test. Significant values are shown in bold.

  • ‡Median (IQR) for AHI was 7.9 (6.7,19.2) for OSAS and 0.4 (0.3,0.7) for controls.

  • §The −25 cm H2O limit was used for 10 (23.8%) OSAS and 20 (54.1%) controls.

  • ¶The −25 cm H2O limit was used for four (9.5%) OSAS and seven (18.9%) controls.

  • AHI, apnoea hypopnoea index; ATV, adenotonsillar volume; BMI, body mass index; HCVR, hypercapnic ventilatory response; NPAV, nasopharyngeal airway volume; OSAS, obstructive sleep apnoea syndrome; Pcrit, critical closing pressure; VE, minute ventilation.