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Evidence From a Meta-analysis of Placebo-Controlled Randomized Trials

Patrick Haentjens, MD, PhD; Alain Van Meerhaeghe, MD; Antonio Moscariello, MD; Sonia De Weerdt, MD; Kris Poppe, MD, PhD; Alain Dupont, MD, PhD; Brigitte Velkeniers, MD, PhD

Arch Intern Med. 2007;167(8):757-764.

Background  Continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea syndrome (OSAS) might lower blood pressure, but evidence from clinical studies is inconsistent, perhaps as a result of small sample size or heterogeneity in study design. This study aimed to assess whether CPAP reduces ambulatory blood pressure in patients with OSAS, to quantify the effect size with precision, and to identify trial characteristics associated with the greatest blood pressure reductions.

Methods  We identified randomized controlled trials of CPAP vs placebo in patients with OSAS specifically reporting 24-hour ambulatory mean blood pressure (MBP).

Results  We included a total of 572 patients from 12 randomized controlled trials. According to a random-effects model, the pooled estimate of the effect of the CPAP intervention was a net decrease of 1.69 mm Hg in 24-hour MBP (95% confidence interval, –2.69 to –0.69). Statistical heterogeneity was moderate (I² = 41%). Predefined metaregression analyses estimated that 24-hour MBP would decrease by 0.89 mm Hg per 10-point increase in apnea-hypopnea index at entry (P = .006), by 0.74 mm Hg for each increase of 10 arousal events per hour slept (P = .008), and by 1.39 mm Hg for each 1-hour increase in effective nightly use of the CPAP device (P = .01).

Conclusions  Among patients with OSAS, CPAP reduces 24-hour ambulatory MBP, with greater treatment-related reductions in ambulatory MBP among patients with a more severe degree of OSAS and a better effective nightly use of the CPAP device. These reductions in blood pressure are likely to contribute to a better prognosis in terms of adverse cardiovascular events.

Author Affiliations: Center for Outcomes Research and Laboratory for Experimental Surgery (Dr Haentjens) and Departments of Pneumology (Dr De Weerdt), Endocrinology (Drs Poppe and Velkeniers), Pharmacology (Dr Dupont), and General Internal Medicine (Drs Poppe and Velkeniers), Universitair Ziekenhuis Brussel, Vrije Universiteit Brussel, Brussels, Belgium; and Service de Pneumologie, Intercommunale de Santé Publique du Pays de Charleroi, Centre Hospitalier Universitaire André Vésale, Montigny-le-Tilleul, Belgium (Drs Van Meerhaeghe and Moscariello).

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