Table 1.
Baseline anthropometric characteristics of study population
| Mild OHSa (n = 46) | Moderate OHSb (n = 24) | Severe OHSc (n = 14) | |
|---|---|---|---|
| Age, yrs | 55 ± 9.3 | 52.2 ± 11.1 | 55.7 ± 6.8 |
| Sex, male/female | 33/13 | 19/5 | 10/4 |
| BMI, kg/m2 | 41.5 ± 8.2 | 45.1 ± 7.3 | 48.7 ± 6.5# |
| ESS | 11.7 ± 5 | 13.7 ± 5.8 | 14.5 ± 4.5 |
| pH | 7.40 ± 0.03 | 7.39 ± 0.04 | 7.39 ± 0.02 |
| PaO2, mmHg | 72.6 ± 6.8 | 66.2 ± 6.5* | 58 ± 6.2**§ |
| PaCO2, mmHg | 46.8 ± 1 | 52.3 ± 1.1* | 57.6 ± 1.8**§ |
| HCO3-, mmol/L | 29.4 ± 1.7 | 33.4 ± 2.4* | 36.8 ± 2**§ |
| FEV1, % predicted | 83.7 ± 15.3 | 76.4 ± 16.3 | 71.4 ± 11.5# |
| FVC, % predicted | 85.1 ± 13.9 | 78.8 ± 15.6 | 73.9 ± 10.9# |
| FEV1/FVC ratio, % | 80.4 ± 6.7 | 80 ± 4.1 | 79.4 ± 4 |
| TLC, % predicted | 90 ± 11.6 | 87.2 ± 16.2 | 82.9 ± 12.1 |
| Hypertension, n (%) | 35 (76) | 19 (79) | 11 (78) |
| Diabetes mellitus, n (%) | 16 (34) | 11 (45) | 8 (57) |
| Dyslipidemia, n (%) | 13 (28) | 8 (33) | 6 (42) |
| Current smokers, n (%) | 11 (23) | 10 (41) | 4 (28) |
| Ex smokers, n (%) | 19 (41) | 4 (16) | 5 (35) |
Data are presented as mean values ± SD unless otherwise indicated
OHS Obesity-Hypoventilation Syndrome, BMI body mass index, ESS Epworth Sleepiness Scale, FEV 1 forced expiratory volume in 1 s, FVC forced vital capacity, TLC total lung capacity
# P < 0.05 severe vs mild OHS; *P < 0.01 moderate vs mild OHS; **P < 0.01 severe vs moderate OHS; § P < 0.01 severe vs mild OHS
a46 mmHg ≤ PaCO2 ≤ 50 mmHg
b51 mmHg ≤ PaCO2 ≤ 55 mmHg
cPaCO2 ≥ 56 mmHg