Factors that affect simulated driving in patients with obstructive sleep apnoea

TABLE 1

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.