Elsevier

Sleep Medicine

Volume 9, Issue 5, July 2008, Pages 494-499
Sleep Medicine

Original Article
Findings of a Berlin Questionnaire survey: Comparison between patients seen in an asthma clinic versus internal medicine clinic,☆☆

https://doi.org/10.1016/j.sleep.2007.06.010Get rights and content

Abstract

Background

Obstructive sleep apnea (OSA) and asthma are common and share similar nocturnal symptoms. We hypothesized that the prevalence of OSA symptoms would be greater in asthmatics compared to a general internal medicine population.

Methods

Patients in the Asthma Clinics (n = 177) and Internal Medicine Clinics (n = 328) at MetroHealth Medical Center, an urban academic institution, were surveyed for OSA risk. Patients completed the Berlin Questionnaire, a validated questionnaire with a positive predictive value (ppv) of 0.89 for determining the presence of OSA in primary care populations. All asthmatics had spirometry performed.

Results

The asthma group had more females (p = 0.01) and a higher mean body mass index (33.2 vs. 31.2 kg/m2, p = 0.02). However, the percentage with a body mass index >30 kg/m2 was not different between the groups (p = 0.19). The internal medicine group had a much higher rate of hypertension (p = 0.002) and diabetes (p < 0.001). Asthmatics were more likely to report frequent snoring (18.5% vs. 8.0%, p < 0.001) and chronic sleepiness (46.1% vs. 34.3%, p = 0.01). OSA risk, as determined by the Berlin Questionnaire, was higher in the asthma group than in the internal medicine group (39.5% vs. 27.2%, p = 0.004). In the asthma group, risk for OSA did not correlate with asthma severity (p = 0.183).

Conclusions

This study suggests a possible association between asthma and OSA. There is a higher prevalence of OSA symptoms in an asthmatic population when compared to a primary care population, independent of the severity of the asthma.

Introduction

Obstructive sleep apnea (OSA) is increasingly common, with recent estimates suggesting a prevalence of 5% [1]. Asthma prevalence has also risen, and it is estimated that 7.5% of adults in the United States are asthmatics [2]. Asthmatics are known to have disturbed and poor sleep, often attributed to nocturnal worsening of their asthma [3], [4]. A survey study found that 39% of patients with various degrees of asthma had disturbed sleep on a nightly basis [5]. Asthmatics also often report increased daytime sleepiness [3], [6]. In a large community-based survey of respiratory symptoms, asthmatics reported a higher prevalence of snoring as compared to the general population [7]. As snoring and daytime sleepiness are common symptoms in OSA, these data suggest a possible association between these two conditions. Recently, it has been suggested that the sleepiness reported by asthmatics is associated with sleep apnea risk and not asthma severity [8]. Of interest, a study of 788 children who underwent in-home unattended sleep studies found an association between sleep-disordered breathing and a history of wheezing, but not a parent-reported diagnosis of asthma [9].

It has yet to be conclusively determined whether asthma and OSA are simply two common conditions with similar symptoms or whether there is a pathophysiologic or causal association between the two. Recent data suggests that OSA is linked to increased bronchial hyperresponsiveness [10] and is an independent risk factor for asthma exacerbations [11]. Furthermore, continuous positive airway pressure (CPAP) treatment of OSA in asthmatics decreases nocturnal asthma symptoms [12], [13] and may improve daytime peak flows [14]. Given these findings and the recognition that OSA is underdiagnosed [15], it is clinically relevant to determine the prevalence of OSA in the asthma population. We hypothesized that, utilizing a validated OSA screening tool, the prevalence of OSA symptoms and thus risk for OSA would be greater in asthmatics when compared to a general internal medicine population.

Section snippets

General study design

A prospective questionnaire survey study was performed in the Asthma Clinics and Internal Medicine Clinics at MetroHealth Medical Center (MHMC) in Cleveland, Ohio. MHMC is an urban academic hospital that serves as the county hospital for Cuyahoga County. The study was performed between October of 2002 and September of 2003. The study was approved by the Institutional Review Board of MHMC. All subjects provided informed consent to participate.

Subjects

We prospectively studied 505 patients and assessed

Results

Of 585 subjects who were approached, 573 (98%) agreed to participate and 563 subjects met the criteria for inclusion (see Fig. 1). Of these, 379 were returned completed from the Internal Medicine Clinics and 184 were returned completed from the Asthma Clinics. Subjects with self-reported OSA were excluded from both clinics (13 subjects in the Internal Medicine Clinics and 7 subjects in the Asthma Clinics). Overall, the refusal to participate rate and the percentage of subjects with reported OSA

Discussion

The primary finding from this study, that asthmatics are more likely to report symptoms suggestive of OSA than non-asthmatics, provides further support that there is an association between these two conditions. While earlier studies suggested that disturbed sleep in asthmatics was predominantly related to poorly controlled nocturnal asthma [3], [6], [20], more recent studies have found that symptoms of OSA, such as snoring and witnessed apneas [8], [21], [22], are common in this population. The

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    This work was previously presented, in part, at the American Thoracic Society Meeting, Orlando, FL, May 25th, 2004.

    ☆☆

    The authors have no financial or other potential conflicts of interest to report.

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