Effect of oral appliances on blood pressure in obstructive sleep apnea: a systematic review and meta-analysis

Abstract

Background: Obstructive sleep apnea (OSA) is an independent risk factor for the development of hypertension. However the effect of continuous positive airway pressure (CPAP) on lowering systemic blood pressure (BP) in OSA patients has been conflicting. Oral appliance (OA) therapy is an important alternative therapy to CPAP for patients with mild to moderate OSA.

Objective: To conduct a meta-analysis of studies which have evaluated the effect of OAs on BP in patients with OSA.

Data sources: Studies were retrieved by searching PubMed (all studies that were published until December 15, 2011)

Study selection: Three independent reviewers screened citations to identify trials of the effect of OA on BP.

Data extraction: Data from observational and randomized controlled trial (RCT) studies was extracted for pre- and post-treatment systolic, diastolic, and mean arterial blood pressure (SBP, DBP, and MAP).

Data synthesis: A total of 7 studies that enrolled 399 participants met the inclusion criteria. The pooled estimate of mean changes and the corresponding 95% CIs for SBP, DBP, and MAP from each trial are -2.7 mm Hg (95% CI: -0.8 to -4.6), p-value 0.04; -2.7 mm Hg (95% CI: -0.9 to -4.6), p-value 0.004; and -2.40 mm Hg (95% CI: -4.01 to -0.80), p-value 0.003 (Figures 2-4). The pooled estimate of mean changes and the corresponding 95% CIs for nocturnal SBP, DBP, and MAP from each trial are -2.0 mm Hg (95% CI: 1.1 to -5.3), p-value 0.212; -1.7 mm Hg (95% CI: -0.1 to -3.2), p-value 0.03; and -1.9 mm Hg (95% CI: 1.3 to -5.1), p-value 0.255 (Figures 5-7) respectively.

Conclusions: The pooled estimate shows a favorable effect of OAs on SBP, MAP, and DBP. Most of the studies were observational. Therefore, more RCTs are warranted involving a larger number of patients and longer treatment periods to confirm the effects of OA on BP.

Figure 1. Flow diagram of articles identified and evaluated during the study selection process

Figure 2. Forest plot for mean change in systolic blood pressure and corresponding 95% CIs

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 3. Forest plot for mean change in diastolic blood pressure and corresponding 95% CIs

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 4. Forest plot for mean change in mean arterial pressure and corresponding 95% CIs

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 5. Forest plot for the mean change in nocturnal systolic blood pressure

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 6. Forest plot for the mean change in nocturnal diastolic blood pressure

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 7. Forest plot for the mean change in nocturnal mean arterial pressure

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 8. Forest plot for the mean change in systolic blood pressure from randomized controlled trials

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 9. Forest plot for the mean change in diastolic blood pressure from the randomized controlled trials

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 10. Forest plot for the mean change in nocturnal diastolic blood pressure from the randomized controlled trials

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 11. Forest plot for the mean change in AHI with oral appliances

SE, standard error; LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.

Figure 12. Forest plot for the correlation of change in AHI reduction and magnitude of change in BP

LL, lower limit; UL; upper limit; Z, Z-value; p, p-value.