Maintenance of Wakefulness Test, obstructive sleep apnea syndrome, and driving risk.
OBJECTIVE
Sleepiness at the wheel is a major risk factor for traffic accidents. Because of the potential medical and legal implications, in this study, we evaluated the correlation between subjective and objective measures of sleepiness and driving performances in patients suffering from excessive daytime sleepiness.


METHODS
Thirty-eight untreated sleep apnea patients (mean age +/- standard deviation, 51 +/- 9 years; mean apnea-hypopnea index +/- standard deviation, 41 +/- 25), and 14 healthy control subjects (mean age +/- standard deviation, 46 +/- 9 years) were included in the study. Nocturnal polysomnography, mean sleep latency as measured by four 40-minute Maintenance of Wakefulness Test (MWT) trials, Epworth Sleepiness Scale, Karolinska Sleepiness Scale, and the number of inappropriate line crossings during a 90-minute real-life driving session were analyzed.


RESULTS
The number of inappropriate line crossings correlated with MWT scores (Spearman's Rho: r = -0.339; p < 0.05), Karolinska Sleepiness Scale scores measured at halfway in total driving distance (Rho: r = 0.367; p < 0.01), and Epworth Sleepiness Scale (Rho: r = 0.389; p < 0.01). We found a significant difference in the number of inappropriate line crossings among the four groups defined by MWT scores (very sleepy [0-19 minutes], sleepy [20-33 minutes], alert [34-40 minutes], and controls) (Kruskal-Wallis test: H = 11.319; p < 0.01). Very sleepy and sleepy patients had more inappropriate line crossings than the control drivers (p < 0.05).


CONCLUSIONS
In addition to subjective sleepiness scales, the MWT can be used to assess driving ability in untreated sleep apnea patients.
Philip
Pierre
P
Université Bordeaux 2, Paris, France. pr.philip@free.fr
Sagaspe
Patricia
P
Taillard
Jacques
J
Chaumet
Guillaume
G
Bayon
Virginie
V
Coste
Olivier
O
Bioulac
Bernard
B
Guilleminault
Christian
C
D000063:Accidents, Traffic; D000328:Adult; D001334:Automobile Driving; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011597:Psychomotor Performance; D012306:Risk; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology; D055815:Young Adult