Obstructive Sleep Apnea in Asthma: Gaining Control by Losing Weight

Obstructive sleep apnea (OSA) affects a significant number of individuals with asthma. However, findings regarding the prevalence of this comorbidity vary considerably across studies. A review published in the Journal of Asthma found rates of OSA ranging from 19.2% to 60.0% in patients with asthma (and 50.0%-95.0% in patients with severe asthma) based on the results from 6 studies that used polysomnography.¹

Co-occurring OSA has been linked to worse clinical outcomes in asthma. In a cross-sectional study published in 2016, for example, patients with asthma with OSA had a higher frequency of severe asthma exacerbations compared with patients without OSA (P <.001) and there was a significant association between the apnea-hypopnea index (AHI) and the occurrence of severe asthma exacerbations (odds ratio [OR], 1.322; 95% CI, 1.148-1.523; P <.001).²

A 2015 study showed that patients with asthma with OSA had significantly worse asthma control (P <.001). In addition, high body mass index (BMI), comorbid gastroesophageal reflux disease (GERD), and asthma severity independently predicted the development of OSA in patients with asthma (P =.03, .034, and <.001, respectively).³ “The pathophysiology of these 2 conditions seems to overlap significantly, as airway obstruction, inflammation, obesity, and several other factors are implicated in the development of both diseases,” wrote the study investigators.^3,4

In research published in 2013, the prevalence of overweight and obesity in patients with asthma was reported to be 64%.⁵ As the top risk factor for OSA (as well as an independent risk factor for asthma), obesity is likely a key contributor to OSA in this population.⁶

However, findings regarding the effects of lifestyle interventions targeting obesity in patients with asthma have been largely inconclusive because of  study design flaws, the variation in asthma outcomes and interventions used, and other factors.⁷ Well-designed studies are needed to further explore the effect of such strategies.

To glean clinician insights on the topic, Pulmonology Advisor interviewed Gaurav Singh, MD, MPH, clinical assistant professor of pulmonary and critical care medicine at Stanford University and clinical assistant professor of psychiatry and behavioral sciences at the Stanford Center for Sleep Sciences and Medicine in California, and Michelle Zeidler, MD, pulmonologist at the University of California, Los Angeles (UCLA), and director of the UCLA Sleep Fellowship Program.

Pulmonology Advisor: What role do lifestyle interventions play in the treatment of patients with comorbid asthma and OSA?

Dr Singh: Lifestyle interventions may be helpful in improving asthma control and severity of OSA, as they share common risk factors. Examples include weight loss and smoking cessation. Obesity is an established risk factor for OSA and asthma, and cigarette smoking can also worsen asthma and OSA symptoms through airway inflammation. Thus, weight loss and smoking cessation can improve both asthma and OSA. Gastroesophageal reflux disease (GERD) may also contribute to poor asthma control and the development of OSA. Lifestyle modification to treat GERD, such as avoiding lying down after a meal and avoiding certain foods, may help. As asthma may worsen OSA, lifestyle modifications for the treatment of asthma, such as reducing exposure to allergens or irritants that trigger asthma, can also be helpful.

Dr Zeidler: Obesity plays a [significant] role in both asthma and OSA, and reducing body weight with a healthy diet and exercise can markedly improve both conditions. In addition, compliance with therapies for both conditions can improve overall health. Poor control of these conditions can feed off each other, leading to overall deterioration. For example, noncompliance with OSA treatment is known to increase asthma exacerbations and noncompliance with asthma therapy can lead to poor sleep, which can exacerbate daytime sleepiness, increase nighttime susceptibility to an unstable airway, and upregulate inflammatory markers.

Pulmonology Advisor: What are clinicians’ biggest challenges in terms of getting patients to begin or continue certain treatments?

Dr Singh: Nonadherence to continuous positive airway pressure (CPAP) and dietary restrictions are common. Although many patients are willing to start these interventions, maintenance is the more challenging aspect. Barriers to treatment adherence include perceived lack of benefit, perceived risk of negative outcomes, discomfort, and inconvenience. One of the main challenges is the lack of frequent follow-up with clinicians early after initiation of these treatments due to limited availability of clinic appointments. Early follow-up has been demonstrated to improve adherence, likely due to early concerns being addressed, but in reality this is often not possible.

Dr Zeidler: Patients can have negative preconceived notions of treatments available for OSA. Many times, patients walk into the office saying, “I will never wear a mask.” They often do not realize how much better they can feel with treatment. Education and communication are the cornerstones of treatment for both OSA and asthma. Unfortunately, many physicians are limited in the amount of time they can spend with each patient and [lack] ancillary staff who [could] also assist. With simple education, encouragement, and an open avenue of communication to ask questions and receive help, most patients can adjust to treatment for OSA and gain benefits from it.

Pulmonology Advisor: Do pulmonologists and sleep specialists generally agree or disagree on the management of patients with these comorbid conditions?

Dr Singh: Since many sleep specialists are pulmonologists, I suspect that they would generally agree on the management of patients with comorbid asthma and OSA, which involves optimal management of asthma and OSA as individual diseases.

However, pulmonologists who do not practice sleep medicine would likely put less emphasis on CPAP, whereas sleep specialists who are not pulmonologists do not typically prescribe inhalers or other therapies for OSA. In my experience, there may also be a misconception among both pulmonologists and sleep specialists that bilevel positive airway pressure (BipAP) is superior to CPAP in the treatment of comorbid asthma and OSA, although there is no evidence of this. I suspect that a specialist in both fields would be [the clinician who would] be most likely to understand this.

Dr Zeidler: Many sleep physicians are pulmonologists and are in tune with the need to treat both disorders. Nonpulmonary sleep specialists are aware of the comorbidity of OSA and asthma.

Pulmonology Advisor: Are there gaps in patient care, particularly regarding sleep studies or nutritional or weight loss counseling in patients with asthma? If so, are these being addressed?

Dr Singh: The optimal PAP treatment modality — CPAP, auto CPAP, BiPAP, auto BiPAP — in patients with asthma-OSA overlap syndrome is not known. The impact of PAP therapy in patients with asthma alone (without OSA) has been studied, but results are uncertain, and further studies are needed. There is more of a defined role and benefit of PAP therapy for patients with COPD. In general, there have been more studies of PAP therapy in patients with COPD and COPD-OSA overlap syndrome compared [with] asthma and asthma-OSA overlap syndrome. Regarding sleep studies, it is recommended that patients with moderate to severe COPD have an in-lab sleep study. A similar recommendation for patients with asthma does not exist, and the appropriateness of a home sleep study vs an in-lab sleep study in patients with severe asthma is not clear.

Dr Zeidler: One of the largest obstacles we face in the treatment of sleep disorders is the lack of training medical students and physicians receive about sleep medicine. The majority of primary care and specialty physicians do not take a sleep history due to either lack of time or lack of awareness about the condition. Continued sleep education endeavors across the country will hopefully change this trend, and we are starting to see the tide shift. Another glaring gap is the current nationwide shortage of sleep physicians, resulting in long wait times to see a sleep physician.

Reference

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2. Wang Y, Liu K, Hu K, et al. Impact of obstructive sleep apnea on severe asthma exacerbations. Sleep Med. 2016;26:1-5.
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7. Nyenhuis SM, Dixon AE, Ma J. Impact of lifestyle interventions targeting healthy diet, physical activity, and weight loss on asthma in adults: what is the evidence?  J Allergy Clin Immunol Pract. 2018;6(3):751-763.