Positional obstructive sleep apnoea – an individualized phenotype

Introduction: In some obstructive sleep apnoea (OSA) patients, the number of events depends on the sleeping position, which may be significantly reduced in non-supine position. We aimed to assess the positional OSA prevalence and understand how these patients differ from the remainder. Methods: Retrospective analysis of OSA patients diagnosed in 2019, with level 3 sleep study and a total test time g 240 minutes. Positional OSA was defined as supine AHI ≥2x non-supine AHI, with at least 20 minutes of sleep in each position. Results: A total of 122 patients were evaluated. Mean AHI was 25.2±22.7, with 49% classified as mild, 21% as moderate and 30% as severe. Positional OSA was identified in 51% of the patients, and 29% also had a non-supine AHIl5. Positional OSA patients were mostly male (71% vs 53%, p=0.045), younger (53±13 vs 58±14, p=0.030), showed lower BMI (32±5 vs 35±8, p=0.005) and were less often obese (63% vs 79%, p=0.048) than non-positional OSA patients. The prevalence of comorbidities such as arterial hypertension (47% vs 75%, p=0.001), diabetes (15% vs 35%, p=0.009) and arrhythmias (11% vs 30%, p=0.010) was also significantly lower than non-positional OSA patients. They also showed lower AHI in the sleep study and most of mild and moderate OSA patients had positional OSA. Conclusion: Positional OSA was observed in more than half of the patients, and a significant percentage showed a non-supine AHIl5. They were younger, had milder OSA and less comorbidities than non-positional OSA patients. The identification of positional OSA has clinical impact, as positional therapy may be offered as an alternative to positive pressure, or as an add-on in order to lower pressures and increase compliance.