Driving risk in obstructive sleep apnoea: Do new European regulations contribute to safer roads?

Obstructive sleep apnea syndrome (OSAS) is a highly prevalent disorder that affects at least 10% of adult males and 5% of adult females [1]. While the disorder is fundamentally based on recurring episodes of partial or complete upper airway occlusion during sleep with associated sleep fragmentation [2], the most prominent daytime symptom of the disorder is excessive sleepiness, which may vary in severity from a tendency to nod off in a comfortable chair to a risk of falling asleep in dangerous situations such as when driving a motor vehicle [3]. Not surprisingly, there is strong evidence that untreated OSAS is associated with a substantial increase in the rate of motor vehicle accidents (MVA), which varies between 2 and 7 times the general population risk in different reports [4,5], and the driving impairment in OSAS patients has been reported as equivalent to driving while drunk [6]. A recent meta-analysis of published reports indicated that the overall increased risk of MVA is 2.4 times that of the general population [7], which exceeds the increased risk of MVA in many other clinical disorders already identified as associated with increased accident risk [8,9]. The role of excessive daytime sleepiness (EDS) in the increased accident risk among patients with OSAS is not fully established [10–12], but the balance of evidence favors EDS as a key factor in this relationship [11,13–15]. This uncertainty likely reflects the fact that other factors may influence EDS in OSAS patients such as inadequate sleep time, poor sleep hygiene, alcohol and other drug usage, and co-morbidities such as cardiac disease [16,17], which are particularly relevant in longdistance truck drivers [18]. Nonetheless, regardless of the association with OSAS, sleepiness itself is recognized as a major risk factor for MVA and has been reported to account for 5–7% of all MVA [19], with a substantially higher risk in fatal accidents and those occurring on motorways. There are many potential warning signs of accident risk in sleepy drivers including yawning and head nodding, lane drift, and inability to remember the most recent distances traveled, in addition to missing planned exits [20]. In these circumstances, many drivers employ countermeasures such as high caffeine drinks and opening the vehicle window. Pulling into a rest area on the highway for a brief nap can also help reduce the impact of sleepiness. Features of MVA that suggest the likelihood of an accident being the result of driver sleepiness include single-vehicle crash of a lone driver, absence of brake marks on the highway, and accidents that occur at night or during the early afternoon [21]. Although OSAS is associated with a substantially increased risk of MVA, there is strong evidence that effective therapy, particularly with continuous positive airway pressure (CPAP), reverses that increase and restores the accident risk to that of an equivalent general population [22]. This improvement is particularly well demonstrated in the Canadian report of George and co-authors that compared a cohort of OSAS patients in the Province of Ontario with the general population of drivers in that province for the two 3-year periods before and after initiation of treatment [23]. They found a 3-fold higher MVA rate in OSAS patients before treatment which fell to the same rate as the general population after treatment commenced. However, despite the reduction in MVA risk consequent to effective therapy, there is evidence that driving simulator performance remains impaired in OSAS patients treated with CPAP [24]. The growing recognition of increased MVA risk in untreated patients with OSAS together with the evidence that effective therapy substantially alleviates that risk has prompted many countries to implement regulations that limit certain categories of OSAS patients to hold a driving license [25]. These regulations vary in the degree of restriction imposed but usually permit OSAS patients complying with effective therapy to continue driving. However, some countries do not have specific regulations regarding OSAS and driving. In the European context, the European Commission has recognized the importance of basic common regulations to be applied throughout the European Union, particularly in the context of open borders between member states where drivers may travel between member states without restriction [26]. In 2012, the Transport and Mobility Directorate of the European Commission established a working group to formally examine the relationship between OSAS and MVA risk and to propose a revision to the Medical Guidelines (Annex III) regarding driver licensing in this disorder. Membership of the group was by nomination from EU member states, thus ensuring a broad European National perspective in the delibera-