Table 1.
Demographic and clinical characteristics of the study population.
| Variable | Total Cohort (n = 443) | Obese Asthma (n = 289) | Healthy-Weight Asthma (n = 154) | P |
|---|---|---|---|---|
| Demographics | ||||
| Age | 10.2 ± 4.1 | 10.8 ± 4.1 | 9.1 ± 4 | < 0.0001 |
| Ethnicity (% Hispanic) | 266 (64.4) | 175 (60.6) | 99 (64.3) | 0.7 |
| Sex (% male) | 256 (57.1) | 163 (56.4) | 93 (60.4) | 0.4 |
| BMI (kg/m2) | 27.3 ± 10.4 | 31.7 ± 9.8 | 19 ± 5.2 | < 0.0001 |
| BMI z-score | 1.7 ± 1.1 | 2.4 ± 0.4 | 0.4 ± 0.8 | < 0.0001 |
| Sleep architecture | ||||
| SE (%) | 82.6 ± 13.5 | 81.4 ± 14.5 | 84.8 ± 11.1 | 0.02 |
| AAIa | 12.8 ± 8.2 | 13.3 ± 9 | 11.8 ± 6.5 | 0.08 |
| Percent time in N1 | 7.1 ± 5.9 | 7.7 ± 6.8 | 5.8 ± 3.4 | 0.005 |
| Percent time in N2 | 46.5 ± 11.1 | 47.6 ± 11.6 | 44.6 ± 9.6 | 0.006 |
| Percent time in N3 | 29.1 ± 11.4 | 28.1 ± 12.2 | 31 ± 9.6 | 0.009 |
| Percent time in REM sleep | 17.7 ± 6.4 | 17.1 ± 6.4 | 18.7 ± 6.1 | 0.01 |
| PLMIa | 22.3 ± 39.7 | 18.7 ± 35.2 | 28.9 ± 46.4 | 0.009 |
| Sleep respiratory parameters | ||||
| AHIa | 4.9 ± 10.3 | 5.9 ± 12.1 | 3.1 ± 5.7 | 0.009 |
| OSA (obstructive AHI > 1.5 events/h) | 190 (42.9) | 129 (44.6) | 61 (39.6) | 0.22 |
| Baseline O2 saturation (%) | 98.2 ± 2.6 | 97.9 ± 3 | 98.6 ± 1.4 | 0.007 |
| O2 saturation nadir (%) | 89.8 ± 8.6 | 89.3 ± 9 | 90.6 ± 7.8 | 0.11 |
| Baseline ETCO2 (mm Hg)b | 40.8 ± 5.5 | 41.3 ± 5.3 | 40.1 ± 5.8 | 0.05 |
| Peak ETCO2b | 48.9 ± 6 | 48.9 ± 6 | 48.8 ± 6.1 | 0.9 |
| Pulmonary function indices | ||||
| FVCc | 93.8 ± 16.6 | 93.9 ± 16.5 | 93.6 ± 16.8 | 0.9 |
| FEV1c | 84.2 ± 17.4 | 83.1 ± 16.5 | 86.4 ± 18.7 | 0.05 |
| FEV1/FVC ratioc | 82.3 ± 8.5 | 81.6 ± 8 | 83.5 ± 9.4 | 0.03 |
| FEF25%–75%c | 75.5 ± 27.1 | 74.8 ± 26.5 | 76.8 ± 28.2 | 0.4 |
| Medication use | ||||
| Inhaled steroids | 339 (76.5) | 214 (74.1) | 125 (81.2) | 0.09 |
| Montelukast | 266 (60.1) | 174 (60.2) | 92 (59.7) | 0.92 |
| Antihistamines | 119 (26.9) | 69 (23.9) | 50 (32.5) | 0.05 |
| Nasal steroids | 133 (30) | 89 (30.8) | 44 (28.6) | 0.63 |
Continuous variables are reported as mean ± SD and categorial variables are reported as proportions, n (%). aReported in events/h. bETCO2 measured in 378 sleep studies. cFVC, FEV1, and FEF25%–75% are reported as percent predicted values while FEV1/FVC ratio is reported as a percentage. AAI = arousal awakening index, AHI = apnea-hypopnea index, BMI = body-mass index, ETCO2 = end-tidal carbon dioxide, FEF25%–75% = forced mid-expiratory flow, FEV1 = forced expiratory volume, FVC = forced vital capacity, OSA = obstructive sleep apnea, PLMI = periodic limb movement index, REM = rapid eye movement, SE = sleep efficiency.