All subjects | Males | Females | p-value | |
Subjects n | 415 | 201 | 214 | |
Demographics | ||||
Age years | 54.7±6.8 | 54.8±6.9 | 54.6±6.8 | 0.74 |
Males | 48.4 | |||
BMI kg·m−2 | 28.2±5.0 | 28.6±4.4 | 27.8±5.4 | 0.10 |
Smoking | ||||
Current | 16.6 | 15.4 | 17.8 | 0.34 |
Former | 44.6 | 48.3 | 41.1 | |
Never | 38.8 | 36.3 | 44.1 | |
Ever had hypertension | 30.6 | 28.4 | 32.7 | 0.34 |
Sleep study | ||||
Apnoea–hypopnea index# | 7.3±9.3 | 9.5±10.4 | 5.2±7.7 | <0.0001 |
Oxygen desaturation index# | 6.6±8.2 | 8.6±9.0 | 4.7±6.9 | <0.0001 |
Hypoxia time#,¶ % | 4.7±12.9 | 5.3±12.4 | 4.2±13.4 | 0.02 |
Minimum SaO2# % | 85.2±5.4 | 84.7±4.9 | 85.8±5.5 | 0.02 |
Symptoms | ||||
Snoring ≥3 per week | 42.3 | 53.7 | 31.1 | <0.0001 |
Nocturnal sweating ≥3 per week | 10.2 | 5.9 | 14.2 | 0.007 |
Dry mouth when awakening ≥3 per week | 18.9 | 14.4 | 22.8 | 0.046 |
Morning headache ≥1 per week | 14.5 | 10.3 | 18.2 | 0.03 |
Difficulties initiating sleep ≥3 per week | 12.6 | 7.9 | 17.1 | 0.006 |
Difficulties maintaining sleep ≥3 per week | 37.6 | 37.8 | 37.4 | 0.94 |
Early morning awakenings ≥3 per week | 13.5 | 13.2 | 13.7 | 0.87 |
Nocturnal GOR symptoms ≥1 per week | 6.1 | 6.5 | 5.9 | 0.81 |
RLS symptoms | 15.9 | 11.1 | 20.3 | 0.01 |
Data are presented as mean±sd or %, unless otherwise stated. Bold type represents statistical significance. BMI: body mass index; SaO2: arterial oxygen saturation; GOR: gastro-oesophageal reflux; RLS: restless legs syndrome. #: n=15 subjects currently on treatment for obstructive sleep apnoea were excluded from comparison. The data were square-root transformed or cubic transformed for statistical analysis as appropriate to normalise distribution; ¶: SaO2 <90%.