Introduction Excessive daytime sleepiness (EDS) is a contributing factor to road traffic accidents, it is assessed using self-administered questionnaires. These assessments are important information when discussing with the Driver and Vehicle Licensing Agency (DVLA) about fitness-to-drive. We hypothesised that patients may be confounded in their assessments after being informed about these potential implications.

Patients and Methods This was a prospective study carried out at a tertiary hospital between June 2017 and July 2017 (registration number: 2017–7478). Patients attending clinics for sleep-disordered breathing were asked to fill in the Epworth Sleepiness Scale (ESS) and the Stanford Sleepiness Scale (SSS) prior to their clinic appointment. Following the consultation, patients were informed about the risk of EDS and driving and they were informed that the DVLA might request information based on their self-assessed sleepiness. They were then asked to fill in the questionnaires a 2nd time. Parameters recorded included age, gender, BMI and driving licence. Results of the ESS and SSS before and after clinic were compared using the student’s t-test for paired observations. Subgroups of patients were analysed based on EDS (ESS≥10) and SSS. Data are presented as mean (SD).

Results 66 subjects were included (41 males, 25 females; age 59.0 (15.7) years, BMI 32.9 (9.11), driving licence held for 27.8 (20.9) years (n=50), smoking 26.9 (28.2) pack years). A total of 25 sleepy and 41 non-sleepy patients were identified. There was no difference in the ESS between the occasions [8.6 (6.2) vs 8.6 (6.2) points; p=0.738] or the SSS [2.5 (1.3) vs 2.4 (1.3) points; p=0.255]. Subgroup analyses based on sleepiness ESS (p=0.108) and SSS (p=0.233) showed no significant differences either. A total of four patients (6.1%) changed their assessment from “sleepy“ to “non-sleepy” and three patients (4.5%) changed from “non-sleepy” to “sleepy” after receiving information about the DVLA.

Discussion Providing patients with information about the risk of driving in the context of sleepiness does not significantly change how they score the extent of their sleepiness using self-administered questionnaires, despite high intra-individual variability in about 1/10 of the patients depending on the information provided.