The effect of high-risk alcohol consumption measured by Audit-C tool, on continuous positive airway pressure (CPAP) compliance in obstructive sleep apnoea syndrome (OSAS)

<bold>Background:</bold> Alcohol use may increase OSAS severity. The Audit-C (AC) tool can identify people at high-risk of alcohol misuse. We hypothesised that raised AC score was associated with increased apnoea/hypopnoea index (AHI), Epworth Sleep Scale (ESS) score, and reduced CPAP compliance. <bold>Methods:</bold> New CPAP prescriptions over a calendar year with recorded baseline ESS, AHI and AC score were identified. Patients with raised AC scores were advised to reduce alcohol intake. Patients received auto-titrating CPAP and were classified retrospectively according to high AC risk (≥3 women, ≥4 men). Compliance was assessed after 3-months according to AC risk and change in AC score following CPAP. <bold>Results:</bold> 172 patients (76% male, mean(SD) age 57(13) years) were identified. 56% had a raised AC score, and these were more likely to be male with lower BMI for a similar level of AHI or ESS score. 158 patients attended follow-up. Baseline AC score was not significantly associated with CPAP %compliance or post-treatment ESS. Increased %compliance and lower ESS were observed in patients whose baseline AC score fell after CPAP. Post-treatment AC score predicted %compliance independent of age, sex, baseline AHI and ESS: compliance fell by 2.7% (95% CI 1.1% to 4.3%, P=0.001) per point increase in AC score. <bold>Discussion:</bold> High-risk alcohol consumption was prevalent in our OSAS population. High-risk AC drinkers had a similar CPAP response; however, improved compliance was seen in patients whose AC score fell. At-risk drinkers with poor CPAP compliance can be identified and may benefit from additional interventions to reduce alcohol consumption.