Obstructive Sleep Apnea Treatment Lowers Blood Pressure
How do continuous positive airway pressure (CPAP) and oral appliances compare in lowering blood pressure (BP) in patients with obstructive sleep apnea (OSA)?
Literature searches for randomized clinical trials comparing the effect of CPAP or mandibular advancement devices (MADs) (vs. each other or an inactive control) on BP in patients with OSA were performed. Studies were analyzed using a network meta-analysis to estimate pooled differences between the interventions. Unlike traditional meta-analysis, this strategy has the advantage of comparing CPAP or MADs with other treatment modalities (like placebo) to be used in the analysis. Using this approach, study power is increased, enabling a better analysis between modalities (Caldwell DM. BMJ 2005;331:897). The main outcome was a change in systolic BP (SBP) and diastolic BP (DBP) from baseline to follow-up.
A total of 872 studies were identified and 51 were selected for analysis, totaling 4,888 patients. One study did not report diastolic DBP. Follow-up ranged from 2 to 52 weeks. Two studies with a follow-up of ≥1 year were excluded. Of these studies, 44 compared CPAP to control (4,289 patients), three compared MADs to control (229 patients), one compared MADs to CPAP (126 patients), and three compared MADs, CPAP, and control (244 patients). CPAP was associated with a reduction in SBP of 2.5 mm Hg (95% confidence interval [CI], 1.5-3.5 mm Hg; p < 0.001) and MADs were associated with a reduction in SBP of 2.1 mm Hg (95% CI, 0.8-3.4 mm Hg; p = 0.002). CPAP was associated with a reduction in DBP of 2.0 mm Hg (95% CI, 1.3-2.7 mm Hg; p < 0.001) and MADs were associated with a reduction in DBP of 1.9 mm Hg (95% CI, 0.5-3.2 mm Hg; p = 0.008).
The authors concluded that both CPAP and MADs similarly reduce SBP and DBP compared to an inactive treatment in patients with OSA.
Efficacy of treating OSA with CPAP is determined in large part by compliance. We still do not know how long patients need to use CPAP at night to obtain its benefit. This report supports the conclusion that CPAP lowers BP in patients with OSA. Although the strongest evidence for effectively treating OSA is with CPAP, in practice, many cannot tolerate it. MADs are recommended by the American Academy of Sleep Medicine for mild to moderate OSA and this study found similar reductions in BP outcomes compared to CPAP. Even though ethical and design challenges exist, a randomized trial using variable duration of CPAP use would help determine the optimal length of time needed to see maximal CPAP benefit on BP and other outcomes.
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