Ventilatory burden and blood pressure response to CPAP: A secondary analysis of the APPLES trial.

Background

Continuous Positive Airway Pressure (CPAP) is the standard treatment of obstructive sleep apnea (OSA), but has a heterogeneous blood pressure (BP) lowering effect. We hypothesized that Ventilatory Burden (VB), a metric better reflecting the entire burden of pathological airflow, may predict CPAP-induced BP reduction.

Methods

We conducted a secondary analysis of the Apnea Positive Pressure Long-term Efficacy Study (APPLES) cohort. Participants were stratified by baseline VB (>20% breaths with < 50% amplitude) and OSA severity (AHI ≥ 30). Linear regression models were used to assess the relationship between these subgroups, CPAP adherence, and morning/evening BP changes at 2 and 6 months. The subgroup analyses were exploratory, and reported p values were nominal.

Results

A total of 962 participants were initially enrolled with complete baseline assessments, of whom 749 completed the 2-month follow-up and 649 completed the 6-month follow-up. At 2 months, active CPAP was associated with a reduction in morning SBP relative to sham CPAP among participants with High VB and good adherence (β = 1.73 mmHg, p = 0.037). This association was not observed at 6 months. In the OSA severity-stratified analysis, active CPAP was associated with morning SBP reduction in the non-severe OSA subgroup with good adherence at both follow-ups.

Conclusion

Among participants with High VB and good CPAP adherence, active CPAP was associated with an early reduction in morning SBP relative to sham CPAP. This association was observed at 2 months but not at 6 months. Prospective studies incorporating prespecified treatment-interaction analyses are required to determine whether VB can identify blood pressure responders to CPAP.