Obstructive sleep apnoea,motor vehicle accidents,and work performance

Abstract

The obstructive sleep apnoea (OSA) shows a very high prevalence in the middle-age work force population and, between all diseases and medical conditions, is the major risk factor for motor vehicle accidents (MVAs). OSA can be diagnosed and treated, with resultant reduction in MVAs to those seen in the healthy population. It is increasing evidence that it is a major risk factor for occupational accidents also in fields different from the professional transport and for work disability. It is likely that the treatment of OSA results in the reduction of occupational accidents and work performance improvement with expected benefits in work processes and business in general. It is therefore advisable to develop strategies for screening and treatment of OSA in workers. The risk assessment of OSA in workers may also help to reduce the burden on national health care systems.

Obstructive sleep apnoea

Obstructive sleep apnoea (OSA) is characterised by recurrent apnoea and/or hypopnoea during sleep where obesity is the primary risk factor. Daytime sleepiness, habitual snoring, and breathing cessation are the key symptoms of OSA. ¹ Its prevalence in the general population of 30 to 60 years of age is 9% in females and 24% in males. ² OSA may result in respiratory failure, ³ and it has been identified as an independent risk factor for increased mortality in cardiac and cerebrovascular diseases. ⁴ It is also a risk factor for motor vehicle accidents (MVAs). ⁵ It has been shown that OSA treatment with continuous positive airway pressure (CPAP) reduces the number of MVAs, ^{6 –10} as compared to the number observed in the general population, ⁹ with a saving of lives and reduction in direct and indirect medical costs. ¹¹ There is also increasing evidence that CPAP treatment prevents or improves respiratory failure as well as cardiovascular and cerebrovascular disease. ^{4,12 –14} In view of the increasing impact that OSA and OSA-related disorders has on the health and social systems of economically advanced countries, the European Union (EU) has approved and funded the European Cooperation in Science and Technology Action B-26 on the cardiovascular consequences of OSAS. One of its working groups (WGs), the WG2 on medical–legal implications of sleep apnoea syndrome, evaluated the correlation between OSA and MVA. ¹⁵

OSA and MVAs

Subjects with OSA have a two- to sevenfold increased risk of being involved in MVAs. ^{5,16 –21} The excessive daytime sleepiness (EDS), responsible for 21.9% of highway accidents, ²² the severity of OSA, ^16,20 changes in brain morphology, ²³ and changes in neural activation associated with cognitive impairment ^{24 –26} are the main contributors to this increased risk. ²³

The incidence of OSA seems to be greater in commercial vehicle drivers than in the general population, ¹⁶ and road accidents due to commercial vehicle drivers (particularly trucks) are often worse than those due to car drivers. According to the EU, ²⁷ the number of car drivers (236,000,000) is huge compared with the number of commercial and professional drivers (823,000 buses and coaches and 33,840,000 goods vehicles). These figures explain why more than 90% of traffic fatalities are due to accidents unrelated to commercial transport. ²⁷

In Europe, more than 1.3 million MVAs each year cause 31,000 deaths and 1.7 million citizens are seriously injured, with a social cost estimated at €53 billion. ²⁸ In Australia, more than 1500 people are killed on roads each year and around 22,000 are seriously injured. The total economic cost exceeds $15 billion annually, and the accompanying social costs greatly impact on communities. ²⁹ In the United States, it has been calculated that OSA treatment with CPAP would save 980 lives each year. In addition, each dollar spent on CPAP treatment saves $3.49 in health and social costs incurred by MVAs. ¹¹

The clinical management of drivers with OSA is hampered by the difficulty in identifying who, among all of them, will cause a MVA. Although a recent study showed a high degree of accuracy in identifying a subgroup of subjects with OSA who failed a simulated driving test, ³⁰ the use of driving simulators does not improve the reliability of a clinician’s decision-making. Indeed, in drivers with severe OSA, it was shown that driving simulator performance remained impaired after 3 months of optimal CPAP treatment. ³¹

Nevertheless, different regulatory approaches have been suggested to reduce and prevent OSA-related road accidents. An approach focused on commercial drivers has been proposed in the United States, instituting a protocol for clinical and therapeutic monitoring of OSA. ³² In Australia, the National Transport Commission and Austroads have indicated medical standards, including subjects with OSA and/or EDS, which commercial and private vehicle drivers must meet to ensure that their health status does not increase their risk of MVA. ²⁹

The WG2 funded by the EU showed that only 10 European countries (Belgium, Finland, France, Germany, the Netherlands, Poland, the United Kingdom, Spain, Sweden, and Hungary) have driving license regulations, which include OSA as a disease to be evaluated when assessing fitness to drive. Even in European countries whose driving license regulations do not take OSA into account, it is still common practice to issue “fitness to drive” status to patients with OSA whether their chronic treatment is effective both in normalising breathing patterns during sleep and obtaining optimal control of symptoms. ¹⁷

The WG2 proposed strategies to implement rules in all EU countries, and addressed proposals to both private and professional drivers, to improve general knowledge on avoidable traffic accident risk factors, particularly concerning excessive sleepiness at the wheel and OSA. ³³ The goal of the WG2, in agreement with the EU Directorate-General Energy and Transport, is to enter OSA in Annex III (physical and mental standards to obtain a driver’s license) for EU countries. ³⁴

The access to diagnosis and treatment of patients with suspected OSA has been evaluated in Australia, Belgium, Canada, the United Kingdom, and the United States. The study, showing a shortest and longest waiting time of 2 and 60 months, respectively, ³⁵ indicates restricted patient access to diagnostic studies and treatment for OSA. Although not all out-of-centre testing devices are appropriate for diagnosing OSA, ³⁶ unattended portable monitors may be used as an alternative to in-laboratory polysomnography for diagnosis in selected subjects. ³⁷ The use of these devices could help to improve access to diagnosis and treatment. Despite the current economic constraints with lack of resources in health care, it is the right of both private and commercial drivers to be identified by OSA screening programs and to be treated as quickly as possible.

OSA and work performance

Every year, according to Eurostat figures, 5720 people die in EU countries as a consequence of work-related accidents and 3.1% of workers have suffered at least one injury. ³⁸ Driving is considered to be a part of work, especially when travelling on mission in the context of work. The analysis of European Statistics on Accidents at Work data reveals that 29% of fatal accidents and 4% of non-fatal accidents are often due to loss of control of the means of transport. ³⁹ More than one third of police officers deaths in the line of duty are related to MVAs. ⁴⁰ In a more recent study involving 4957 police officers, almost half reported having fallen asleep while driving and about one quarter stated that this occurs one to two times per month. Of the 4957 participants, 2003 screened positive for at least one sleep disorder, most (1666, 33.6% of the total cohort) for OSA. ⁴¹ These data, although provided by different studies, strongly suggest that OSA is the leading cause of death from MVA at work. It is worth mentioning that the link between OSA and MVA at work is documented in police officers, a group of workers that apparently recognises the dangers related to drowsy driving. They regard drowsy driving to be as dangerous as drunk driving. ⁴²

It is known that sleep disorders and EDS are also the risk factors for occupational accidents in non-professional transport fields. ^{43 –47} As mentioned previously, OSA may result in EDS and neurocognitive disorders such as difficulty concentrating, memory loss, and impaired learning ability. ^12,13,48 Despite the fact that OSA may be expected to adversely affect work performance, recent observations showing the impact of OSA on work ability are relatively few.

Studies carried out in workers who screened positive for snoring ^49,50 or OSA ⁵⁰ by means of questionnaires, reported a significantly increased risk of injury in an occupational accident. Occupational accidents are significantly higher in white- and blue-collar workers with OSA, ^49,51 being more common in the latter group. ⁴⁹ A telephone interview of 10,000 participants showed that, relative to a control group, workers at risk of OSA were at increased odds (0.1–4.2) for negative work performance outcomes. These outcomes were grouped into cognitive, mood, presenteeism, and missed work time domains. ⁴³ A more recent study performed in subjects who underwent night-time polysomnograpy ⁵² shows that patients with OSA have a probability of incurring a work disability or work duty modification 2.6 times higher than non-OSA controls. This risk increases up to 13.7 times in OSA with associated EDS. A prospective study, ⁵³ carried out in 7028 subjects aged 40–45 years, showed that self-reported symptoms (snoring, breathing cessation, and daytime sleepiness) are significant predictors of work disability and long-term sick leave. Even after controlling a range of possible adverse confounding factors, OSA symptoms remained an independent risk factor for the evaluated work outcomes. A significant decrease in days absent from work was observed in a group of patients with OSA after 6 months of CPAP treatment. ⁵⁴

These results, although they should be confirmed in larger series of subjects undergoing polysomnography, show evidence that OSA significantly contributes to occupational accidents and impaired work performance. Therefore, it seems mandatory to develop and implement strategies for screening and treatment of workers with OSA as a part of the medical assessment in a working environment. In 2002, a study in Italy showed that the health costs of OSA-related occupational accidents amounted to €101,083,761 euros. ⁵⁵ Therefore, OSA risk assessment in workers may also help to reduce the burden on national health care systems.

Conclusions

OSA has a very high prevalence in the general population, particularly in the middle-aged work force. It is also known that, in addition to increasing risk of diseases and medical conditions, it is the major independent risk factor for MVA. There is increasing evidence that OSA is also a major risk factor for occupational accidents and work disabilities. It is well-recognised that OSA can be diagnosed and treated, with resultant reduction in MVA rates to those seen in the non-OSA population. It is therefore likely that its treatment could likewise significantly reduce the number of occupational accidents and improve work performance, with expected benefits in work processes and business in general. Finally, like the evaluation of fitness to drive, health surveillance in the workplace must take into account OSA as a risk factor for occupational accidents and/or reduction in working capacity.