Anxiety Disorders in Patients With COPD—Reply
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* Abebaw Mengistu Yohannes

*In reply:*

We are most grateful for Dr Alkhuja's intriguing comments on our review published in Respiratory Care.1 He raised 2 important, inter-related questions. First, Dr Alkhuja highlights the importance of under-diagnosed comorbidities and their consequences in patients with COPD. In this context, comorbid obstructive sleep apnea (OSA) in patients with COPD, which is often described as the overlap syndrome, is under-recognized and inadequately managed in COPD patients. A recent elegant study by Mann and co-workers2 found that untreated overlap syndrome in COPD patients was associated with elevated risk of death and hospitalization due to exacerbation, compared to patients who used CPAP. Furthermore, the overlap of COPD with OSA may increase the susceptibility to arterial stiffness, which in turn predisposes to pulmonary hypertension3 and decline in cognitive function.

Second, the association of overlap syndrome with comorbid anxiety has not been fully investigated. This is partly due to the over-lapping clinical symptoms of COPD that may mask the symptoms of OSA. This requires specialized training in sleep medicine for the healthcare professionals (eg, primary care physicians and advanced practice nurses) and comprehensive assessment to detect OSA in COPD patients.

The focus of our systematic review was primarily to underscore the prevalence and the existence of a wide range of clinical anxiety disorders in patients with COPD, which are often not fully recognized and treated. Therefore, we have not explored the association between overlap syndrome and/or OSA in patients with COPD. However, we concur with Alkhuja that OSA is a disabling comorbid disease that may be a risk factor for anxiety.4 The co-occurrence of OSA in COPD patients increases the frequency of oxygen desaturation,4 defragments the quality or quantity of sleep due to hypoxemia and hypercapnia, and results in depression, somnolence, and daytime dreaming.5 All these factors contribute to COPD patients' increasing burden and worsening prognosis of anxiety symptoms and dependence on their caregivers. Hence, regular screening and monitoring for OSA and anxiety symptoms in patients with COPD is worthy of consideration. Indeed, it will be the first step to detect these disorders and refer patients to sleep centers to receive appropriate treatment.

Finally, there is a lack of robust data on the impact of overlap syndrome and the potential mechanism and its association with cardiovascular disease and COPD. Thus, further studies are required to examine the role of hypoxemia, systemic inflammation, OSA, and clinical anxiety in patients with COPD.

*   Copyright © 2013 by Daedalus Enterprises

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