Prevalence of OSA in USA Railway Workers

by | Jun 6, 2016 | american sleep apnea society, obstructive sleep apnea, train

Prevalence of OSA in the general population

What is the prevalence of moderate-to-severe obstructive sleep apnea (OSA) among the general adult U.S. population? 

The best available data suggests that sleep apnea is present in 9% of women and 24% of men ages 30 to 60 in the United States. This comes from the Wisconsin Cohort, a large epidemiological study, which found that self-reported sleepiness was also present in 2% of women and 4% of men leading to a diagnosis of sleep apnea syndrome.1 Wide ranges of OSA prevalence exists in population studies of sleep apnea and sleep apnea syndrome. Much of this variation can be attributed to the different ways sleep apnea and sleep can be measured.

How does this prevalence vary by age? 

In the United States, a program for monitoring OSA over time isn’t available to provide us with a good estimate of prevalence by age. A model developed using data from the United Kingdom to estimate the prevalence of mild, moderate and severe OSA by age groups in the US2 shows that age and body mass index (BMI) influence the prevalence of all types of OSA. Evidence in railway workers suggests individuals who have a BMI ≥ 25 and are over 37 years old have a higher incidence of OSA.3

Prevalence of OSA in USA railway workers

What is prevalence of moderate-to-severe OSA among individuals occupying safety sensitive transportation positions? If it differs from that among the general population, why does it appear to do so?

The prevalence of sleep apnea in train operators has been shown to be higher than the general population. The reason is likely related to the number of train operators who are male, overweight, smoke, operate in shifts and have other risk factors for OSA.3

Prevalence and risk factors for obstructive sleep apnea syndrome in railway operators was examined in 2 studies3, 4 totaling 1,163 employees. The first study, which examined railway drivers* in Brazil who had an average age of 35.63 years and a mean BMI of 26.74, found that 35% of workers were diagnosed with Obstructive Sleep Apnea Syndrome. This included individuals who had mild apnea (Apnea Hypopnea Index, AHI of 5-14) and also had daytime sleepiness that could impair the operation of a train. The majority of workers of workers over 37 years old (51%) had sleep apnea. Since approximately 54.4% of the workers in the study were diagnosed with mild OSA, 25.3% with moderate OSA, and 20.3% with severe OSA, approximately 23% of those over 37 years of age had moderate to severe OSA (assuming an equal distribution across age and BMI in the study).

The second study examined railway drivers in Greece and found OSA in 62% of workers whose average age and BMI was 47 years and 28.7, respectively. Similar to the Brazil railway drivers, where 23% were found to have moderate to severe apnea, 22% of the Greek railway drivers had moderate to severe apnea.4

Data on transportation workers in the US show similar descriptive statistics to the railway workers in Greece. For example, US transportation workers have an average BMI of 28.5 5 and an average age of 44.6,6 demographics that are strikingly similar to the cohort of Greek railway drivers (BMI of 28.7 and average age of 47). Generalization of these studies might be made to a US group of railroad workers, in lieu of actual OSA prevalence data from railway workers in the United States.

*The term train “conductors” utilized in the study “Prevalence of and risk factors for obstructive sleep apnea syndrome in Brazilian railroad workers” refers to “drivers.” This is implied in the article and was confirmed by email correspondence with the author, Renata Koyama, on 5/17/16.

References:

  1. Lee W, Nagubadi S, Kryger MH, Mokhlesi B. Epidemiology of Obstructive Sleep Apnea: a Population-based Perspective. Expert review of respiratory medicine. 2008;2(3):349-364. doi:10.1586/17476348.2.3.349. (Link)
  2. Peppard, Paul E., et al. “Increased prevalence of sleep-disordered breathing in adults.” American journal of epidemiology(2013): kws342. (Link)
  3. Koyama, Renata G., et al. “Prevalence of and risk factors for obstructive sleep apnea syndrome in Brazilian railroad workers.” Sleep medicine8 (2012): 1028-1032. (Link)
  4. Nena, Evangelia, et al. “Sleep-disordered breathing and quality of life of railway drivers in Greece.” CHEST Journal1 (2008): 79-86. (Link)
  5. Luckhaupt, Sara E., et al. “Prevalence of obesity among US workers and associations with occupational factors.” American journal of preventive medicine3 (2014): 237-248. (Link)
  6. The U.S. Bureau of labor Statistics. (2013).Employed persons by detailed industry and age. Retrieved from http://www.bls.gov/cps/industry_age.htm (Link)