Assessment of Comprehensive Patient-Reported Outcomes Before and After CPAP Therapy in Obstructive Sleep Apnea

<b>Background</b>: Obstructive sleep apnea (OSA) impacts daytime alertness, mood, cognition, and quality of life (QoL). Initial alterations in these patient-reported outcomes (PROs) following CPAP therapy, along with their association with adherence and residual respiratory events, are only partially understood. <b>Materials and methods</b>: We conducted a retrospective, observational study from January 2024 to May 2025 involving adult patients with OSA. Standardized assessments were performed at baseline and at six months following the initiation of CPAP: Epworth Sleepiness Scale (ESS), WHOQOL-BREF, MoCA, DASS-21, GAD-7, and PHQ-9. The primary endpoint was the change in Patient-Reported Outcomes (PROs) and cognitive performance. The second was to identify associations between these improvements and the degree of adherence to CPAP therapy and residual AHI. <b>Results</b>: Seventy-two patients (median age, 57; 65.3% male) with moderate to severe OSA had a baseline median AHI of 34.5/h, ODI of 35.5/h, and a mean nocturnal SpO₂ of 92.4%. The initial burden was high: median ESS was 14, indicating excessive daytime sleepiness (EDS), present in 68.9%; median MoCA was 24, with 98.6% scoring below 26; median PHQ-9 was 7; median GAD-7 was 5; and 56.8% and 47.9% scored below 50 in physical and psychological domains of WHOQOL-BREF, respectively. After 6 months, group averages showed improvement: ESS decreased to 8.6 ± 3.7, with a 27.0% residual EDS; PHQ-9 was 7.1 ± 4.5; GAD-7 was 6.2 ± 4.1; and MoCA increased to 25.3 ± 2.7, although 48.6% still showed impairment. WHOQOL-BREF scores improved across domains: physical 58.7 ± 14.2, psychological 61.5 ± 13.6, social 63.2 ± 15.4, and environmental 59.8 ± 14.7, with fewer scores below 50 (physical 23.0%, psychological 18.9%). CPAP adherence was high, with a mean of 87.7% and a median of 95%, predicting a greater ESS reduction (<i>p</i> = 0.027) and showing a trend toward improvement in PHQ-9 scores (ρ = 0.218; <i>p</i> = 0.066). Residual respiratory indices at 6 months (AHI, ODI, SpO₂) did not correlate with PRO or cognitive scores at the same time point (all <i>p</i> > 0.16), nor with their change scores. <b>Conclusions</b>: Over the course of six months, CPAP therapy led to notable improvements in sleepiness, mood, anxiety, cognition, and overall quality of life. Nonetheless, many patients continued to face residual problems, mainly excessive daytime sleepiness (EDS) and cognitive challenges. The positive effects were more closely associated with how well patients adhered to the treatment than with remaining levels of residual AHI or ODI.