Objectives/hypothesis: To determine if a relationship exists between depression, disease severity, and sleepiness in patients with obstructive sleep apnea (OSA).
Study design: Case control study.
Methods: Fifty-three consecutive patients with suspected OSA were evaluated before treatment and compared with controls by using the Beck Depression Inventory (BDI), Epworth Sleepiness Scale (ESS), and polysomnography.
Results: OSA was associated with an increased risk of depression in the study group compared to the control group (odds ratio = 6.3, 95% confidence interval: 1.9-20.6, P = .002); depression was seen in 35% of OSA patients and 8% of controls (P < .001). There was a significant correlation between BDI and ESS scores (r = 0.342, P = .012). In addition, ESS was significantly associated (P = .039) with depression in a linear regression model that controlled for race, sex, age, and respiratory disturbance index (RDI). RDI and depression were weakly associated (P = .056) in this model, and there was no correlation found between BDI scores and OSA disease severity (RDI)(r = 0.446).
Conclusions: Patients with OSA and daytime sleepiness are more likely to have depressive symptoms as compared with controls. OSA disease severity, as measured with the RDI score, is a weak predictor of BDI score, and no correlation was seen between the severity of OSA and BDI scores after controlling for other factors. However, there was a strong correlation between sleepiness (ESS) and disease severity (BDI). These data suggest that OSA patients with symptoms of excessive sleepiness have the highest risk of associated depressive symptoms and may benefit most from depression screening.