A visual analog scale for the assessment of mild sleepiness in patients with obstructive sleep apnea and healthy participants

MOTIVATION: Studies have shown poor clinical effectiveness of the Epworth Sleepiness Scale (ESS) due to its ambiguity of items and cultural applicability. This study aimed to investigate the efficacy of a Visual Analog Scale (VAS) to assess sleepiness, compared to ESS. METHODS: Thirty-two obstructive sleep apnea (OSA) patients and 32 healthy participants completed two visits, 1 month apart, during which they completed both ESS and VAS. Patients diagnosed with OSA were treated with Continuous positive airway pressure (CPAP) between visits. The agreement between the ESS and VAS scores in both patients with OSA and healthy participants was investigated using Pearson correlation and Area Under the receiver operating characteristics. RESULTS: The (mean ± standard deviation) Oxygen Desaturation Index for patients with OSA was 18.5 ± 5.7 events/hour and 1.7 ± 1.0 events/hour in the healthy participants. A reduction in sleepiness, following CPAP treatment occurred in patients with OSA, using the ESS (11.2 ± 5.5-4.7 ± 5.0 points, P < 0.001) and the VAS (50.2 ± 3.0-21.9 ± 26.5 mm, P < 0.001). There was no significant change in sleepiness, in healthy participants using the ESS (3.91 ± 3.14-3.34 ± 3.27 points (P < 0.48) or the VAS (15.58 ± 21.21-12.05 ± 14.75 mm, (P < 0.44). A Likert scale showed that the VAS was easier to use compared to ESS in visit 1 (VAS: 8.7 ± 1.9 points, ESS: 7.7 ± 2.6 points, (P < 0.001), and visit 2 (VAS: 9.5 ± 1.4 points, ESS: 8.6 ± 1.5 points, P < 0.001). CONCLUSION: These preliminary results suggest that the VAS can detect a change in sleepiness after CPAP treatment in patients with OSA and that the VAS was also easier to use compared to ESS.