Potential underdiagnosis of obstructive sleep apnoea in the cardiology outpatient setting.

Introduction: Consistent evidence suggests that obstructive sleep apnoea (OSA) is associated with increased cardiovascular risk. However, it is unclear whether OSA is underdiagnosed in the cardiology outpatient setting. In the present study, we prospectively evaluated the potential underdiagnosis of OSA in several subspecialties from a tertiary cardiology university hospital.

Methods: Consecutive outpatients from five subspecialties (hypertension, coronary, arrhythmia, heart failure (HF), valvular heart disease) were studied. We performed anthropometric measurements, assessed the risk of OSA using the Berlin Questionnaire and evaluated the prior diagnosis and treatment for OSA. In a subset of patients randomly selected, we performed portable sleep monitoring to objectively evaluate the presence of OSA (defined by an apnoea-hypopnoea index ≥15 events/h of sleep).

Results: We evaluated 500 patients (100 from each subspecialty). The mean age and body mass index (BMI) were 59±13 years and 28.2±5.3 kg/m(2), respectively. We found that 51.6% (258 patients) had a high risk for OSA (Berlin Questionnaire). However, only 13 (3.1%) of these patients had a previous diagnosis of OSA. Of those, only six patients were receiving specific OSA treatment. Fifty patients (10 from each specialty) participated in sleep studies. No differences were found in patients who underwent sleep monitoring and those who did not. We found a high frequency of OSA (66%), varying from 50% (hypertension group) to 80% (HF group).

Conclusions: Despite significant scientific evidence pointing to OSA as an emerging cardiovascular risk factor, OSA is still underdiagnosed in several cardiology subspecialties.