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Introduction Excessive daytime sleepiness (EDS) in obstructive sleep apnoea (OSA) has important public health implications. The Oxford Sleep Resistance Test (OSLER) is a tool in sleep medicine to assess fitness to drive, by evaluating a subject’s daytime vigilance and ability to maintain wakefulness, and Sheffield Teaching Hospitals provides a tertiary sleep service, including OSLER, for patients with OSA.Aims and Objectives This retrospective cohort study evaluates use of OSLER in assessing fitness to drive and its real-life implications.Methods We analysed data over a 5-year period and recorded sleep diagnostics, clinical information, Epworth Sleepiness Score (ESS), OSLER data, and DVLA outcome. Follow-up phone calls were conducted to assess present-day symptoms and implications of OSLER on driving, lifestyle, and occupation.Results We identified 26 patients with OSA who were referred for OSLER over a 5-year period.Four patients failed OSLER, but one patient disputed their result and passed a repeat test with no errors. One patient had difficulties understanding OSLER principles and had multiple attempts. He subsequently failed, but was recorded as a lack of concentration rather than a microsleep. One patient who failed OSLER was lost to follow up, but later reported severe ongoing symptoms and was unable to work as a lorry driver, leading to financial difficulties and mental health problems.In 13/26 patients, DVLA were notified of sleep investigations. In 6/26 patients, it is unclear whether DVLA were contacted, and one of these failed OSLER. Over half the patients continued to drive with no recorded accidents or near misses. Overall, two patients had their driving license revoked.Abstract S74 Table 1Demographic and sleep diagnostics results in the ‘passed OSLER’ and ‘failed OSLER’ patient groups Passed OSLER (n=22) Failed OSLER (n=4) Demographics Mean age at initial assessment (years) 55.5 61.8 Mean BMI 34.4 33.7 Gender (n=males) 15 (68%) 2 (50%) Number of occupational drivers 9 (40.1%) 2 (50%) Sleep diagnostics Severity of OSA Mild 4 (18.0%) 0 Moderate 6 (27.3%) 1 (25.0%) Severe 12 (54.5%) 3 (75.0%) Mean baseline ESS 12.3 12.0 Feels tired when driving? 3 (13.6%) 1 (25.0%) History of road traffic accident/near miss 0 1 (25.0%) Mean Apnoea-Hypnoea Index (AHI) 28.5 29.5 Median Oxygen desaturation index (ODI ) 37.6 53.5 Conclusion Majority of patients passed OSLER, but interpretation was subjective and open to patient opinion. ESS, EDS whilst driving, and AHI were poorly predictive of OSLER result, but the majority who failed OSLER had severe OSA. Patient self-awareness of sleepiness while driving does not appear to correlate with OSLER outcomes. We need a better way of assessing driving risk (e.g. driver-specific questionnaire and modern driving simulator) and clearer guidance from DVLA, as outcomes have implications on patient occupation and well-being.