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/m(2), p=0.02). However, the percentage with a body mass index >30 kg/m(2) 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.