Impact of rail medical standard on obstructive sleep apnoea prevalence.
BACKGROUND
The 2004 edition of the National Standard for Health Assessment of Rail Safety Workers (the standard) used the Epworth Sleepiness Scale (ESS) to screen for excessive daytime sleepiness related to obstructive sleep apnoea (OSA). The 2012 edition of the standard expanded the OSA screening matrix to include body mass index, comorbid hypertension and type 2 diabetes as triggers requiring a sleep study to be undertaken irrespective of the ESS.


OBJECTIVE
To assess the impact of the new standard on the estimated prevalence of OSA in railway workers.


METHODS
An analysis of data on safety critical employees referred for rail safety health assessment during the 2013 calendar year and meeting the criteria for sleep study referral. Sleep study outcomes were used to assess the predictive value of screening under the new standard.


RESULTS
A total of 200/4311 workers were investigated with a sleep study. One hundred and ninety-three met the new risk factor criteria and 182 (91%) were newly diagnosed with OSA. The prevalence of OSA in the study population was 7%, compared with 2% in 2009. No worker reported an elevated ESS. The false positive to true positive ratio was 0.1 (95% CI 0.06-0.16).


CONCLUSIONS
The new medical standard has resulted in an increased estimate of the prevalence of OSA in rail workers. This study supports the use of objective clinical risk factors to select workers for further investigation, aiming to minimize the risk of accidents associated with excessive daytime sleepiness and other comorbid conditions of OSA.
Sonic HealthPlus, Sydney, New South Wales 2000, Australia.
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Colquhoun
Sydney Trains, Haymarket, New South Wales 1238, Australia. armand.casolin@transport.nsw.go.au.
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Casolin
D000056:Accident Prevention; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D005260:Female; D006801:Humans; D006973:Hypertension / Q000150:complications; D008297:Male; D008403:Mass Screening / Q000592:standards*; D008875:Middle Aged; D009790:Occupations; D017063:Outcome Assessment, Health Care; D015995:Prevalence; D011890:Railroads; D012016:Reference Values; D012307:Risk Factors; D012449:Safety; D012890:Sleep; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology; D014851:Wakefulness; D014937:Work; D014938:Work Capacity Evaluation; D055815:Young Adult
Medical standards; obstructive sleep apnoea; rail; safety critical work; screening.