The effect of CPAP on quality of life in patients with ‘very’ mild Obstructive Sleep Apnoea (OSA): Results from a subset of the MERGE Randomised Trial

Background: The efficacy of CPAP at the mildest end of the OSA spectrum is unclear. The MERGE trial investigated the effect of CPAP on quality of life in patients with mild OSA (Wimms et al. 2019). This subset analysis aimed to determine the effectiveness of CPAP in a subset of patients with ‘very9 mild OSA, defined as having mild OSA according to the sensitive AASM 2012 criteria, but no OSA using the earlier AASM 2007 criteria (i.e. AHI >5 to Methods: The MERGE trial randomised patients with mild OSA (AHI >5 to ≤15 events/hr, AASM 2007 or 2012) in parallel to receive either CPAP plus Standard Care or Standard Care alone for 3 months. A subset of 95 of 301 patients were identified as having ‘very9 mild OSA. Results: The subset of 95 ‘very9 mild OSA patients had a median (IQR) AHI 6.80(5.7, 8.8) events/hr, and were symptomatic (Vitality 41.9(10.9); ESS 10.3(4.7)). 50 of 95 were allocated to CPAP, and 45 to Standard Care. ‘Very9 mild OSA patients had significantly improved Vitality after 3 months of CPAP, compared to Standard Care (+9.2 points, 95% CI +5.6 to +12.7; p Conclusions: This subset analysis has shown the clinical effectiveness of CPAP treatment in patients at the mildest end of the disease spectrum, with 9very9 mild but symptomatic OSA. The results were similar to those observed in the primary analysis of the MERGE trial.