Distribution and outcomes of t-tests and Chi-squared tests
| Parameters | Fail | Not fail | p-value | Chi-squared or Fisher's exact test OR (95% CI) |
| Patients n | 32 | 101 | ||
| Patient parameters | ||||
| Age years | 50±11 | 52±10 | 0.32 | |
| BMI kg·m−2 | 34±6.1 | 35±6.7 | 0.8 | |
| Females | 7 (22) | 8 (8) | 0.04 | 3.2 (1–9.8) |
| Clinical parameters | ||||
| ESS score | 13±6 | 11±5 | 0.04 | |
| AHI events per h | 34±24 | 27±19 | 0.15 | |
| ODI events per h | 38±27 | 29±23 | 0.08 | |
| Driving parameters | ||||
| Duration for which licence held years | 30±10 | 32±11 | 0.3 | |
| Annual distance driven >10 000 miles# | 15 (50) | 49 (54) | 0.6 | 1.2 (0.5–2.7) |
| Predominantly local journeys | 17 (55) | 55 (55) | 0.85 | 0.92 (0.4–2) |
| HGV/PSV drivers | 1 (3) | 11 (11) | 0.18 | 0.26 (0.03–2.1) |
| Driving questionnaire parameters | ||||
| Taking a break at <1 h during long journeys | 7 (22) | 2 (2) | <0.001 | 13 (2.6–68) |
| Likelihood of feeling slightly sleepy while driving | 25 (80) | 65 (65) | 0.09 | 2.3 (0.86–6.1) |
| Likelihood of feeling moderately sleepy while driving | 19 (61) | 40 (40) | 0.033 | 2.4 (1.0–5.5) |
| Likelihood of feeling highly sleepy while driving | 12 (39) | 16 (16) | 0.006 | 3.3 (1.3–8.2) |
| Nodded off while driving in the last year | 14 (48) | 24 (24) | 0.014 | 2.9 (1.1–4.0) |
| Hit the rumble strip on motorway | 12 (40) | 30 (32) | 0.33 | 1.4 (0.6–3.2) |
| Near misses in last 1 year | 8 (27) | 20 (20) | 0.43 | 1.4 (0.56–3.7) |
| Any accidents in last 3 years | 11 (37) | 22 (22) | 0.09 | 2. 0 (0.86–5.0) |
| Simulator parameter | ||||
| Study performed in the afternoon | 16 (50) | 45 (45) | 0.59 | 0.8 (0.3–1.7) |
Data are presented as mean±sd or n (%), unless otherwise stated. BMI: body mass index; ESS: Epworth Sleepiness Scale; AHI: apnoea–hypopnoea index; ODI: oxygen desaturation index; HGV: heavy goods vehicle; PSV: public service vehicle. #: ∼16 000 km.