The association between the effective apnea-hypopnea index and blood pressure reduction efficacy following CPAP/oxygen treatment

Background: The effect of sleep apnea treatment on reducing cardiovascular disease risk remains inconclusive. This study aims to assess if the effective apnea hypopnea index (eAHI), a measure of residual sleep apnea burden post -treatment, is a factor in determining blood pressure (BP) response to continuous positive airway pressure therapy. The eAHI integrates time on therapy, residual apnea, and % of sleep time untreated. Methods: A secondary analysis of the Heart Biomarker Evaluation in Apnea Treatment (HeartBEAT) study, a randomized, controlled, parallel group assessment of continuous positive airway pressure (CPAP), oxygen and sleep hygiene. The Delta-AHI (triangle AHI) was defined as the difference between baseline AHI and effective AHI at 12 weeks. Logistic and linear regression models estimated the predictors for nocturnal systolic BP change following sleep apnea therapy. Results: One hundred and sixty-nine subjects with a mean age of 62.82 +/- 6.99 years were included in the final analysis. Fifty subjects had triangle AHI <= 8/hour of sleep and 119 subjects were higher. After adjustment, baseline mean nighttime systolic blood pressure (OR 1.036, 95% CI 1.015 - 1.058, p: 0.001) and triangle AHI >= 8/hour (OR 2.406 , 95% CI 1.116 - 5.185 , p :0.025) were independent predictors for mean nighttime systolic blood pressure change > 3 mm Hg. The higher effective AHI was negatively related with BNP (beta: - 2.564 , SE: 1.167 , p: 0.029) and positively related with troponin change (8 : 0.703 , SE: 0.256 , p: 0.007). Conclusion: The triangle AHI was an independent predictor of the blood pressure response to sleep apnea treatment. Register number: NCT01086800.