Objectives
The relationship between anxiety and obstructive sleep apnea (OSA) has not been well studied. We evaluated the factors associated with anxiety and whether anxiety is related to quality of life (QoL) independently of depression in OSA patients.
Methods
Data were collected from adults with newly diagnosed, untreated OSA. The State-Trait Anxiety Inventory–State Scale (STAI-S), the Beck Depression Inventory (BDI), the Epworth Sleepiness Scale (ESS), and the Short Form 36 Health survey (SF-36) were used. Anxiety and depression were defined as high levels of anxiety symptoms (STAI-S score ≥ 40) and depressive symptoms (BDI ≥ 10), respectively. Associations between anxiety and OSA were analyzed using multiple linear regression analysis.
Results
Of 655 OSA subjects included, the prevalence of anxiety and depression was 48.4% and 46.4%, respectively. The scores of STAI-S had strong correlations with BDI (r = 0.676, p < 0.001). Female sex (p < 0.05), excessive daytime sleepiness (ESS ≥ 10) (p < 0.05), and a lower educational level (p < 0.05) were identified as independent factors for predicting the presence of anxiety in OSA patients. The severity of OSA measured by the apnea–hypopnea index or respiratory distress index was not related to comorbid anxiety. In linear regression analysis, both anxiety (ß = − 10.196, p < 0.001) and depression (ß = − 16.317, p < 0.001) were independently associated with lower SF-36 scores in OSA patients.
Conclusions
The presence of anxiety can be predicted by female sex, daytime sleepiness, and a lower educational level. Both anxiety and depression were independently associated with a lower QoL in OSA patients.
Obstructive sleep apnea (OSA) is the most common type of sleep apnea [1]. The characteristic feature of OSA is a transient and repetitive obstruction of the upper airway during sleep. These episodes of airway obstruction cause intermittent periods of oxygen desaturation and arousal from sleep, resulting in fragmented sleep. The prevalence of OSA was estimated from large population studies, such as the Sleep Heart Health study, to be up to 18% [2]. Untreated OSA is often associated with cardiovascular disease [3] and [4]. Symptoms reported by OSA patients include fatigue, daytime sleepiness, poor sleep quality, impaired concentration, memory loss, headache, and mood and affect disturbance [5]. OSA has a significant impact on individuals' daytime functioning, increasing traffic accidents and decreasing work productivity [6].
The physical effects of OSA and its treatment have been extensively investigated, but the psychological aspects of OSA, especially anxiety, have not drawn as much attention [7]. In fact, the relationship between anxiety and OSA is not addressed in the clinical guidelines for the management of OSA [8]. The prevalence of anxiety ranges from 11% to 70% [7] in OSA patients and individuals with a diagnosis of sleep apnea have increased odds of receiving anxiety disorder diagnosis [9], whereas the relationship between anxiety and OSA is unclear [7]. For example, the severity of OSA was not found in previous investigations to be related to accompanying anxiety [5], [7] and [10]. In addition, the effectiveness of continuous positive airway pressure (CPAP) treatment on anxiety is not consistent in the literature [7]. For example, Kingshott et al. [11] reported that anxiety significantly declined after 6 months of CPAP treatment. In contrast, Munoz et al. [12] failed to find a significant decline in anxiety after 3 and 12 months of CPAP treatment.
Although the role of OSA as a cause of anxiety is still unknown, it is clear that the presence of comorbid anxiety significantly impacts the health-related quality of life (QoL) of OSA patients [13]. In other diseases, depression is considered to be an extremely important determinant of QoL. For example, depression has a greater negative impact on QoL in patients with epilepsy than other clinical indicators such as seizure frequency [14]. In light of the strong association of depression and anxiety with OSA [10] and [13], it is possible that they strongly affect the QoL of OSA patients. However, the relationship between these mood disturbances and QoL in patients with OSA has not been well studied [13]. Therefore, in our current study, we investigated the relationship between OSA and comorbid anxiety in newly diagnosed, untreated OSA patients. The aims of our present analyses were threefold: (1) to determine the prevalence of anxiety in OSA patients; (2) to identify the factors associated with anxiety in OSA patients; and (3) to determine whether anxiety is related to QoL independently of the status of depression in OSA patients.
Of 863 consecutive patients who underwent overnight PSG for suspected OSA, 774 were diagnosed with OSA (AHI ≥ 5/h). Of these, 119 patients were excluded, due to medical problems (cardiac disease, n = 13; pulmonary disease, n = 9; cancer, n = 6; thyroid problems, n = 5; gastrointestinal disorder, n = 4; and other problems, n = 3), neurologic disease (n = 15), psychiatric disease (major depression, n = 5; panic disorder, n = 2; bipolar disorder, n = 1; and schizophrenia, n = 1), sleep disorder (n = 4), previous diagnosis with and treatment for OSA (n = 6), a periodic limb movement arousal index ≥ 5/h (n = 30), and incomplete data (n = 15). The remaining 655 OSA subjects (569 men and 86 women) participated in the study ( Table 1). The average age was 49.8 years (SD = 11.7 years). The mean AHI was 28.5/h (SD = 20.1/h). Of these patients, 205 (31.3%) were classified as having mild OSA (5/h ≤ AHI < 15/h), 199 (30.4%) as having moderate OSA (15/h ≤ AHI < 30/h), and 251 (38.3%) as having severe OSA (AHI ≥ 30/h).
