Commercial truck drivers could be incorrectly reporting symptoms of sleep apnea due to their fears of endangering their employment, according to a new study released at the European Respiratory Society’s (ERS) Annual Congress in Vienna.

“Our study suggests that commercial drivers are playing down their levels of sleepiness for fear of losing their jobs,” said Dr. Werner Strobel, University Hospital, Switzerland and lead author of the study.

Strobel said that although this is very difficult to prove, that data recovered from a study of commercial drivers versus a control group of patients indicates commercial drivers downplayed their sleepiness compared to other patients.

Researchers examined 37 commercial vehicle drivers with sleep apnea and compared them with a control group of 74 patients. Both groups had similar characteristics of age, body mass index (BMI) and similar numbers of disturbances suffered on average during the night.

“You would therefore expect their reports of sleepiness to be similar to begin with, however the (commercial) drivers estimated their levels of sleepiness as lower than the non-drivers,” Strobel said. “This pattern continued throughout the course of the study, with drivers reporting lower symptoms, yet receiving less treatment and making more unscheduled visits to the clinic.”

Both groups also underwent treatment using Continuous Positive Airway Pressure (CPAP) — the regular treatment for sleep apnea which uses a mask and other equipment to generate a stream of air to keep the upper airway open during sleep.

Levels of sleepiness were then analyzed using the Epworth Sleepiness Score; a well-established short questionnaire used to give levels of sleepiness during the day. The survey provides a score, which is the sum of eight items and can range between 0 and 24 - the higher the score, the higher the person’s level of daytime sleepiness.

At the start of the study, commercial drivers reported an average score of 8.1 on the sleepiness scale, compared with an average of 11.0 reported by non-commercial drivers, despite a similar number of disturbances at night between the two groups. The difference was also seen after six months of treatment using CPAP therapy with the drivers reporting an average sleepiness score of 4.8 and non-drivers reporting an average of 7.7.

The results also showed that drivers received less treatment (only receiving CPAP for an average of 75% of days, compared with 83%) and also had more unscheduled visits to the clinic, which suggests they were struggling with their symptoms. As commercial drivers regularly do shift work, they don’t follow regular patterns of sleep and also do not always sleep in one place; this makes adherence to CPAP treatment more difficult, researchers said.

The authors speculate that the lower scores reported by the commercial drivers could be due to drivers under-scoring their sleepiness levels for fear of losing their license.

“We can assume from these results that commercial drivers with sleep apnea symptoms could be under-reporting their sleepiness in order to protect their job,” Strobel added. “These results should be taken into account by healthcare professionals who are treating this group of people.”