Introduction Obstructive Sleep Apnoea (OSA) is a common condition, highly prevalent but under-recognized in patients with a Mental Health Diagnosis (MHD). Patients with MHD have a higher prevalence of risk factors such as obesity, diabetes, hypertension, hyperlipidaemia, tobacco smoking, alcohol consumption and sedative medication use. Continuous Positive Airway Pressure (CPAP) therapy is effective in reducing sleepiness and improving quality of life. However, treatment adherence may be low, which can compromise its effectiveness.

Method We performed a Service Audit by reviewing clinical data regarding all patients in the Sleep Unit at Lister Hospital who have been prescribed CPAP therapy between June 2011 and July 2018 (n=2642), with the aim of determining the prevalence of MHD and characterizing the population and adherence to treatment.

Results Out of the 2642 patients who were included in the audit:

• 2018 (76.4%) were using CPAP

• 624 (23.6%) stopped CPAP treatment for various reasons

• 442 (16.7%) had a MHD

Within the MHD group, there was similar age, gender distribution and BMI. [Table 1].

Discussion The CPAP treatment adherence rate in our service is 76.4%, which is higher than reported in literature. The percentage of patients with MHD is lower than expected (16.7%), as it is estimated that 39% of the adults in the UK suffer with common mental health disorders. There is a higher percentage of MHD in the dropout group (21.29%) than in the CPAP group (15.71%), despite similar age, BMI and gender distribution, suggesting this may be a factor in achieving compliance with CPAP treatment.