Am J Respir Crit Care Med Published online July 11, 2022 | www.atsjournals.org/doi/abs/10.1164/rccm.202202-0366OC
Digest author(s): Matteo Siciliano | 26 June, 2023
It is well-known that obstructive sleep apnoea (OSA) is associated with cardiovascular (CV) disease. The impact of positive airway pressure (PAP) therapy on cardiovascular outcomes in OSA patients is still currently debated. Previous observational studies showed potential benefit of PAP treatment on cardiovascular outcome, although recent randomized controlled trials (RCTs) did not find a significant effect. However, patient selection and low PAP therapy preclude the generalization of RCTs data, lacking association between PAP therapy and secondary CV disease.
Gervès-Pinquié et al. aimed to evaluate whether long term PAP therapy has a preventive effect on CV outcomes in terms of major adverse CV events (MACEs, composite outcome of mortality, stroke and cardiac disease). This study was performed using data from the Pays-de-la-Loire Sleep Cohort (PLSC), which included patients with a diagnosis of OSA (Apnoea Hypopnoea Index [AHI] >5/h evaluated by either in lab polysomnography or home sleep apnoea testing ) who had started PAP treatment according to OSA severity and presence of CV comorbidities or severe daytime sleepiness. Adherence to CV active drugs was assessed too. Patients were divided into four groups according to quartiles of the average daily PAP use [0-4h/night; 4-6h/night; 6-7h/night; ≥7h/night]. Cox proportional analyses were used to evaluate the associations between quartiles of average daily use and incident of MACEs.
The final study sample comprised 5138 patients; considering non-adherent patients ([0-4[ h/night) as the reference group, adjusted hazard ratios [95% confidence interval] for MACEs were 0.87 [0.73-1.04] for the [4-6[ h/night group, 0.75 [0.62-0.92] for the [6-7[ h/night group and 0.78 [0.65-0.93] for the ≥7h/night group (p =0.0130).
Authors demonstrated a negative dose-response relationship indicating that higher PAP adherence was associated with a lower incidence of MACEs [reduction of 25% circa in patients using PAP at least 6h/night compared to non-adherent patients]; this association was more pronounced in male patients, patients without overt CV disease at diagnosis and those with excessive daytime sleepiness. Regarding sleep apnoea specific hypoxic burden (SASHB), a novel measure which includes frequency, duration and depth of respiratory event-related desaturations, the present study also showed that patients with higher SASHB values at baseline showed the greatest reduction in MACEs among PAP adherent patients, although formal test for interaction was not significant. Furthermore, the study found a significant association between PAP adherence and all-cause mortality [p=0,0006] but the association did not reach statistical significance for all non-fatal CV events. The study demonstrated a slight but significant association between PAP adherence and adherence to CV active drugs (particularly anti-hypertensive and lipid lowering drugs). No association of PAP adherence with MACEs in the subgroup with preexisting CV disease were shown, suggesting that PAP might be more effective for the primary prevention of CV disease than in reversing an altered vascular structure as a secondary prevention strategy.
Achieving and maintaining adherence to PAP therapy remains challenging, requiring a multidisciplinary approach and the use of novel technologies. Clinical phenotyping might be useful for early identification of OSA patients in whom adherent PAP therapy is most likely to improve CV outcomes.