Anxiety Disorders in Patients With COPD

To the editor:

We read the interesting review by Willgoss and Yohannes “Anxiety Disorders in Patients With COPD: A Systemic Review.”¹ Willgoss et al found similarly high levels of anxiety in both in-patient and out-patient samples, and suggested that such a high incidence cannot be explained solely by the presence of an exacerbation-related hospitalization. Rather, anxiety in patients with COPD is most likely to be a chronic and disease-related phenomenon.¹ Their findings also revealed the high prevalence of specific anxiety disorders, including panic disorder and phobic anxiety disorders, with panic disorder being particularly common in patients with COPD.¹

However, one of the common, yet under-diagnosed, comorbidities that complicates the clinical picture of patients with COPD is the overlap syndrome: the coexistence of obstructive sleep apnea (OSA) and COPD.^2,3 Lacedonia et al studied 720 patients with suspected OSA, of whom 168 had overlap syndrome, and 86 had COPD.⁴ They found that the overlap syndrome group had lower daytime P_aO2 than the OSA group, and the diurnal P_aO2 in the overlap syndrome group correlated with age and with FEV₁.⁴ Overlap syndrome causes more severe nocturnal hypoxemia than either OSA or COPD alone.^2,4 Therefore, overlap syndrome contributes to daytime hypoxemia and the embarrassing breathlessness, resulting in worsening anxiety and social phobia.

Furthermore, patients with overlap syndrome experience nocturnal hypoxemia, especially during rapid eye movement sleep,² resulting in nighttime awakening, which may be associated with “sensation of suffocation or choking” and fear of death. Those episodes may carry nighttime anxiety to daytime, making anxiety a 24 hour ongoing disorder.

Clinical screening for overlap syndrome should be part of the evaluation of anxiety in patients with COPD, and that should be followed by polysomnography if warranted.³ Appropriate therapy for overlap syndrome, which may include CPAP and nocturnal oxygen, should be applied. Lack of this therapy may make other treatment modalities, such as antidepressants and psychotherapy, not as effective in reducing anxiety, panic attacks, and number of hospital admissions in patients with COPD.

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