Effect of non-respiratory arousals on residual sleepiness in CPAP-treated OSA patients

<bold>Objective:</bold> To test the impact of the ratio of non-respiratory to total arousals (NRAR) at baseline polysomnography on residual sleepiness (RES) evolution in obstructive sleep apnea (OSA) patients treated with Continuous Positive Airway Pressure (CPAP). <bold>Methods:</bold> We included treated OSA patients from the ESADA cohort with available arousal data who had at least 2 follow-up visits. Primary outcome was RES under CPAP measured with the Epworth Sleepiness Scale (ESS). Based on NRAR values, patients were stratified in tertiles. A linear mixed model tested the effect of NRAR tertiles on RES over time. Baseline variables that differed significantly between groups were added as covariates. <bold>Results:</bold> 800 patients (69.6% male, median age 58y) were evaluated at a median of 152, 470, and 637 days after CPAP initiation. ESS score at visit 3 was higher in the high NRAR tertile compared to other groups (p=0.003; Table). In the multivariate model, compared to overall mean ESS score across visits, the low NRAR tertile had lower ESS score by 1.07 (95% CI=0.66-1.48) and 1.76 (1.23-2.28) units, while the high NRAR tertile had higher ESS score by 1.02 (0.47-1.57) and 1.06 (0.39-1.73) units in visits 2 and 3 respectively. Effects were independent of sex, comorbidities, body mass index, blood pressure, baseline AHI and ESS, visit intervals, and mean CPAP adherence across visits. <bold>Conclusions:</bold> NRAR could be a novel biomarker of arousability and is related with RES in OSA patients treated with CPAP. <table-wrap><object-id>erj;64/suppl_68/PA3541/TB1</object-id><object-id>T1</object-id><object-id>TB1</object-id><table><colgroup><col></col><col></col><col></col><col></col><col></col><col></col><col></col></colgroup><tbody><tr><td></td><td></td><td>Low NRAR</td><td>Intermediate NRAR</td><td>High NRAR</td><td>p-value</td><td>Post-hoc</td></tr><tr><td></td><td>Visit 1</td><td>6(6)</td><td>7(6)</td><td>6(5)</td><td>0.356</td><td>-</td></tr><tr><td>Median ESS score (IQR)</td><td>Visit 2</td><td>5(5)</td><td>6(5)</td><td>6(5)</td><td>0.087</td><td>-</td></tr><tr><td></td><td>Visit 3</td><td>4(5)</td><td>4(6)</td><td>6(5)</td><td>0.003</td><td>3>1,2</td></tr></tbody></table></table-wrap>