The sleep disorders screening questionnaire used validated, self-report screening tools for OSA (Berlin Questionnaire; sensitivity 0.86, specificity 0.77), moderate to severe insomnia (Athens Insomnia Scale: sensitivity 0.93, specificity 0.85),20 restless legs syndrome (RLS Epidemiology, Symptoms, and Treatment questionnaire: sensitivity 0.82, specificity 0.90),21 and narcolepsy with cataplexy (Cataplexy Questionnaire: sensitivity 0.92, specificity 0.9522 and Epworth Sleepiness Scale [ESS]23). For shift work disorder, we created a screening tool based on the International Classification of Sleep Disorders, Second Edition (ICSD-2) diagnostic criteria. The municipal police department allowed that only the OSA risk could be assessed for its 659 participants. Excessive sleepiness was assessed using the ESS (sensitivity 0.94, specificity 1.00) to examine prevalence of this symptom and to compare across positive and negative sleep disorder groups.
In the baseline survey, participants reported current health status (poor to excellent); previous diagnoses of sleep and other medical disorders (eg, diabetes, cardiovascular disease, gastrointestinal tract disorder, depression, anxiety); likelihood of falling asleep while driving after work; and use of sleeping medications (never or nearly never to nearly every day), caffeine (0-_8 servings/d), and alcohol (0- _14 servings/wk). The Maslach Burnout Inventory was used to assess 2 subscales of burnout: emotional exhaustion and depersonalization. In the monthly surveys, participants were asked about work and sleep hours, likelihood of falling asleep in various situations and outcome measures of work performance, such as administrative errors, injuries, uncontrolled anger toward suspects or citizens, absenteeism, citizen complaints, and safety violations. The workhours instrument was previously validated against daily work diaries (for monthly work hours, r =0.76; for extended shifts, r=0.94; P_.001), which in themselves were validated by direct observation (r=0.98, P_.001).
Polysomnographic Assessment
To compare questionnaire OSA screening outcome with polysomnography, full, attended polysomnography studies were performed for 126 participants from the state police department. Of these, 63 had screened positive on the Berlin questionnaire and were the first from the overall study to agree to have sleep studies performed and agree to provide the investigators with access to relevant medical records; 61 had screened negative on the Berlin questionnaire and were selected randomly from the group of participants who screened negative; and 2 had invalid Berlin screening outcomes. Obstructive sleep apnea severity was classified by a sleep specialist, blind to questionnaire outcome, and was made on the basis of both the respiratory disturbance index and the minimal arterial oxyhemoglobin saturation level associated with respiratory disturbances.