The objective was to assess the effect of continuous positive airway pressure (CPAP) on symptoms of anxiety and depression in patients with obstructive sleep apnea (OSA). We hypothesized a decrease in symptoms at follow-up, but that improvement relied on CPAP adherence.
The sample comprised 468 patients (mean age 55.5 years (SD = 12.0), 72% men) with OSA who received CPAP at a Norwegian hospital. OSA was diagnosed according to standard respiratory polygraphy. Mean baseline respiratory event index (REI) was 28.4 (SD = 20.6). Symptoms of anxiety and depression were assessed prior to CPAP treatment and at follow-up after a median of 20 weeks, range 6-52 weeks, with the Hospital Anxiety and Depression Scale (HADS). Patients were classified as CPAP adherent (≥ 4 h per night) or non-adherent (< 4 h per night).
There was a significant decrease in anxiety scores from baseline (mean = 5.16, SD = 3.94) to follow-up (mean = 4.76, SD = 3.81), p < 0.001. Similarly, depression scores decreased from baseline (mean = 4.31, SD = 3.66) to follow-up (mean = 3.89, SD = 3.69), p < 0.001. Cohen's d (0.19 and 0.18, respectively) indicated small effect sizes. The reduction in anxiety scores did not depend on CPAP adherence (no interaction effect F(1, 466) = 0.422, p = 0.516), whereas the reduction in depression scores were seen only in the CPAP adherent group (interaction effect F(1, 466) = 7.738, p = 0.006).
We found a decrease in symptoms of anxiety and depression from baseline to follow-up of CPAP treatment. The improvement in symptoms of depression was depending on CPAP adherence. This underlines the importance of adherence for optimal effect of CPAP treatment.