Effect of Continuous Positive Airway Pressure (CPAP) Treatment in the Control of Refractory Hypertension
Condition: Sleep Apnea; Hypertension
MeSH terms: Sleep Apnea Syndromes; Hypertension
Study type: Interventional

Summary: 
      The working hypothesis for the present study is that treatment with CPAP in patients with an
      sleep apnea (IAH>15) and AHT-r is capable of producing significant reductions in
      blood-pressure levels.

      This hypothesis is supported by four proven findings:

        1. -sleep apnea is an independent risk factor for arterial hypertension (1).

        2. -The greater the number of RSD, the greater the loss of control over blood-pressure
           levels (1).

        3. -The prevalence of sleep apnea in patients with AHT refractory to treatment is very high
           (11,12).

        4. -Treatment of patients with sleep apnea and AHT-r with CPAP succeeds in significantly
           reducing blood-pressure levels in the only (small-scale) studies undertaken to date
           (14,15).

      4. OBJECTIVES

      Main objective:

      To evaluate the effect of treatment with CPAP on blood-pressure levels in patients with AHT
      refractory to medical treatment.

      Secondary objectives:

        -  To evaluate the effect of treatment with CPAP on the various elements assessed in BP
           (systolic/diastolic; daytime/nighttime, etc) and the circadian profile
           (dipper/non-dipper/raiser patterns; variability and homogeneity of blood-pressure
           levels, etc) obtained during a 24-hour out-patient study (AMPA).

        -  To analyze the related variables or subgroups of patients most affected by treatment
           with CPAP.

        -  To evaluate the effect of CPAP on the levels of some of the biological variables
           involved in the pathogenesis of AHT-r (renin, angiotensin, aldosterone, atrial
           natriuretic factor, etc).
    

Detailed description: 
      OBJECTIVE. To evaluate the effect of continuous positive airway pressure (CPAP) treatment on
      the blood-pressure (BP) levels of patients with refractory arterial hypertension (AHT-r).

      METHODS: Multicenter randomized study with parallel groups and blind final evaluation.

      Patients will be recruited from AHT, nephrology or internal medicine outpatient clinics and
      will satisfy the criteria for AHT-r (patients requiring 3 anti-AHT drugs at recommended doses
      to maintain their blood-pressure levels within AMPA [24-hours ambulatory monitoring of blood
      pressure values) excluding those forms of secondary AHT and those patients with
      incapacitating hypersomnia that need immediate treatment. In all, 210 patients will be
      included (105 per arm for intention to treat analysis) in accordance with the calculation of
      the sample size needed including drop-outs to evaluate a clinically significant minimum drop
      of 4-5 mmHg in the mean BP and the number of centers (21 centers; 10 patients per center).
      They will all be subjected to a complete clinical history, an AMPA study, a blood test (with
      serum retained for a later determination of biological mediators) and a sleep study. Those
      patients with an AHI>15 will be randomized to receive CPAP vs habitual control. The treatment
      will last 3 months. The same variables that were measured before the randomization will be
      analyzed again for the purposes of comparison. The comparison of results will be undertaken
      on the basis of an intention-to-treat and per-protocol analyses based on adherence to CPAP
      treatment at different cutoff of hours /day by means of an ANOVA two-way analysis (one of
      them being time).
    

Intervention name(s): CPAP
Intervention type(s): Device
Intervention description(s): Pressure device on airway to maintain it open
Other intervention name(s): Continuous positive airway pressure
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Investigator, Outcomes Assessor)
Primary purpose: Treatment
Keywords: Sleep apnea; Refractory Hypertension; Difficult-to-treat hypertension; CPAP