Study of the Relationships Between Refractory Hypertension, Overweight/Obesity and Sleep Apnea Syndrome
Condition: Refractory Hypertension
MeSH terms: Sleep Apnea Syndromes; Hypertension; Obesity; Overweight
Study type: Interventional
Phase: Phase 3

Summary: 
      The purpose of the study is to investigate the links between blood pressure (BP), overweight
      or obesity, and sleep apnea syndrome (SAS), by studying a large cohort of subjects suffering
      from refractory hypertension.

      Primary objective

        -  To compare plasmatic leptin levels in patients suffering from refractory hypertension
           depending on whether or not they experience SAS.

      Secondary objectives

        -  To ascertain what determines the difference in plasmatic leptin concentrations in
           patients suffering from refractory hypertension depending on whether or not they
           experience SAS.

        -  To characterise BP readings (from clinical and ambulatory (ABPM) measurements) in
           patients suffering from refractory hypertension depending on whether or not they
           experience SAS.

        -  To characterise metabolic parameters (lipids, glycaemia, adiponectin) and sympathetic
           nervous system effectors (adrenaline, noradrenaline and metanephrines) in patients
           suffering from refractory hypertension depending on whether or not they experience SAS.

        -  To characterise BP readings, metabolic parameters and sympathetic nervous system
           effectors in patients suffering from refractory hypertension according to the severity
           of the SAS (in those who experience this problem).

        -  To study, in patients with both SAS and refractory hypertension, the impact of nasal
           continuous positive airway pressure (CPAP) treatment on BP readings, metabolic
           parameters and sympathetic nervous system effectors, by comparing those who are
           compliant with the CPAP regimen with those who are non-compliant.
    

Detailed description: 
      A number of factors predispose subjects to both hypertension and SAS, including
      overweight/obesity and hyperinsulinism. The pathogenesis of concomitant overweight/obesity
      and hypertension is multifactorial. There is an independent relationship between the degree
      of insulin resistance and the severity of SAS. A number of studies have suggested that
      hormones secreted by adipose tissue are involved in the pathogenesis of both hypertension and
      SAS, and overweight/obesity has been shown to be associated with elevated leptin levels
      coupled with reduced adiponectin levels.

      Leptin is produced in adipose tissue and its levels rise with overweight/obesity due to
      peripheral resistance to its action. A number of studies have detected high leptinemia in
      both hypertensives and people suffering from SAS. Leptin may activate the sympathetic nervous
      system and promote SAS-related hypertension.

      Adiponectin which is also produced in adipose tissue has beneficial activities, notably on
      atherogenesis. A relationship between hypertension and adiponectin has yet to be
      demonstrated.

      Unlike leptin, adiponectin levels do not seem to be elevated in patients with SAS.

      In terms of treatment, a number of studies have shown that CPAP has a positive effect on BP
      readings. Although this effect is modest, it is greater in subjects with SAS and rises with
      the severity of this condition. The effects of CPAP on plasmatic leptin and adiponectin
      levels are as yet unknown.
    

Intervention name(s): nCPAP
Intervention type(s): Device
Intervention description(s): Active nCPAP
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Refractory hypertension; Obstructive sleep apnea syndrome; Obesity; Leptinemia; RHOOSAS study