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the CPAP group. These positive findings were only observed in patients who used
CPAP more than 5.8 h [ 41 ]. In the study by Dernaika et al., CPAP treatment resulted
in de-escalation of antihypertensive treatment in 71% of subjects with RH [ 42 ].
In a study by Cantolla et al. [ 43 ] performed on patients with a new diagnosis of
HT and OSAS, 12 weeks of CPAP treatment significantly decreased 24-h ambula-
tory BP of 2 mmHg and nocturnal systolic BP of 3.1 mmHg. Also percentage of
patients with non-dipping HT was reduced in the CPAP group. Adherence to CPAP
treatment is known to be important in effective treatment of OSAS-induced HT [ 13 ,
44 ]. Similarly in this study, the reduction in BP was higher in patients with a CPAP
use of more than 3 h/night.
In the study by Pedrosa et al. [ 45 ], patients with confirmed RH and moderate to
severe OSAS were randomized to medical therapy or to medical treatment plus
CPAP for 6 months. The treatment of OSAS with CPAP significantly reduced day-
time BP in patients with RH.
In the study by Muxfeldt et al. [ 46 ], 117 patients with RH and moderate to severe
OSAS were randomized to 6 months of CPAP treatment or no therapy while main-
taining antihypertensive treatments. CPAP treatment was not effective on clinic and
ambulatory BP levels; however nighttime systolic and nocturnal BP levels might be
affected favorably in patients with uncontrolled ambulatory BP levels.
In a large prospective multicenter RCT performed on 725 non-sleepy patients with
OSAS, CPAP did not result in a statistically significant reduction in the incidence of
HT or cardiovascular events during a median follow-up period of 4 years [ 47 ].
CPAP treatment may also be effective in patients with prehypertension and
masked HT. In the randomized study by Drager et al. [ 48 ] performed on patients
with severe OSAS, 3 months of effective treatment with CPAP significantly
decreased BP and resulted in a 42% decrease in the frequency of prehypertension
and an 87% decrease in the frequency of masked HT. Authors concluded that these
results might suggest that OSAS might be a risk factor for both prehypertension and
masked HT and that the early treatment of OSAS might prevent the development of
sustained HT.
Summary of the meta-analyses about the role of CPAP on the treatment of HT is
presented in Table 20.1. Accordingly, the overall treatment effects were modest but
still significant except one meta-analysis by Alajmi et al. [ 49 ]. Even these moderate
improvements in BP have been shown to reduce morbidity and mortality [ 50 ].
Importance of CPAP Adherence
The efficacy of CPAP as an antihypertensive treatment is significantly associated
with the numbers of hours of adherence to CPAP. Each hour of CPAP use was found
to be associated with a 1.3 mmHg reduction in mean BP in patients with OSAS and
RH [ 40 ]. Similarly, in several other studies, at least 5 h of CPAP use/night was
shown to significantly decrease BP [ 41 , 44 ]. However, adherence to CPAP is usually
low. Average CPAP use in clinical trials is usually around 4–5 h/night. Even if the
A. Özkök et al.