Mediterranean Diet/Lifestyle Intervention in Obstructive Sleep Apnea
Condition: Obstructive Sleep Apnea
MeSH terms: Apnea; Sleep Apnea Syndromes; Sleep Apnea, Obstructive
Study type: Interventional

Summary: 
      Obstructive sleep apnea (OSA) is a sleep disorder characterized by recurrent episodes of
      partial or complete collapse of the upper airway during sleep, leading to pauses of breathing
      and arousals. Although previously considered as a local abnormality of the respiratory track,
      it is nowadays recognized as a systemic disease and an important cause of morbidity and
      mortality, since it is strongly associated with obesity (especially abdominal obesity) and
      cardiometabolic diseases, including cardiovascular diseases and diabetes mellitus.
      Interestingly, recent hypotheses support that the metabolic syndrome pathology, including
      insulin resistance, inflammation and oxidative stress may be involved in OSA pathogenesis.
      The modification of lifestyle habits, e.g. in terms of diet and physical activity, is
      currently explored as a mean of managing the disease in combination with the first line
      treatment, i.e., the application of continuous positive airway pressure (CPAP) during sleep.
      The available data support that weight loss, achieved through lifestyle modification,
      effectively reduces the severity of OSA and improves the associated cardiometabolic disorders
      in overweight or obese patients. However, studies exploring the potential effect of diet's
      quality or other lifestyle habits (such as physical activity) on OSA severity, besides weight
      loss, are currently lacking. Given that a Mediterranean dietary pattern, as well as other
      lifestyle habits adopted by the populations in the Mediterranean region, have been proven
      beneficial both for the prevention and the resolution of the metabolic syndrome and its
      associated cardiometabolic diseases, the aim of the present randomized, controlled,
      single-blind study is to implement an intensive intervention based on the Mediterranean
      lifestyle (hypocaloric diet and 7 group lifestyle counselling sessions) and to evaluate its
      potential benefits, compared with standard care (hypocaloric diet and written advice for
      healthy lifestyle), in a sample of patients with OSA.
    

Detailed description: 
      Obstructive sleep apnoea (OSA) is a chronic disease characterized by recurrent complete or
      partial interruptions of breathing during sleep due to obstruction of the upper airways,
      which leads to disturbances in gas exchange, hypoxia and consequent arousals. Beyond its
      adverse impact on sleep duration, sleep quality, as well as the functionality and cognitive
      function during the day (typical symptoms include fatigue, sleepiness, decreased reflexes,
      impaired memory, etc.). OSA is currently recognized as a major cause of morbidity and
      mortality due to its strong association with obesity and cardiometabolic diseases, including
      the metabolic syndrome (and its individual components, namely abdominal adiposity, impaired
      fasting glucose, dyslipidaemia and hypertension), cardiovascular diseases and diabetes
      mellitus. According to epidemiological data, its prevalence ranges from 2% to 7% in the
      general population (with a clear lead of obese middle-aged men), however it is estimated that
      a large proportion of patients (70-80%) remain undiagnosed making the disease a major public
      health challenge for the 21st century. Currently, the first line treatment for the management
      of moderate-to-severe OSA or mild OSA accompanied by symptoms (such as daytime sleepiness and
      cognitive disorders) and other diseases (such as hypertension and heart disease) is the
      application of continuous positive airway pressure (CPAP) during sleep, usually via a renal
      mask. CPAP has been proven effective in alleviating the symptoms of the disease (e.g. pauses
      of breathing during sleep and daytime sleepiness), however it is also characterized by high
      rates of non-compliance and its effectiveness in improving cardiometabolic indices has not
      yet been confirmed.

      Given the strong relationship of OSA with obesity and its concomitant metabolic disorders, as
      well as the aforementioned restrictions of the use of CPAP as the sole treatment for the
      disease, lifestyle changes have currently emerged as a promising treatment for OSA. Indeed,
      several interventional studies have investigated the effect of lifestyle changes on the
      treatment of OSA, focusing primarily on weight loss - achieved through a hypocaloric diet,
      either solely or in combination with exercise and lifestyle counselling - and the available
      data support its effectiveness in reducing the severity of the disease and improving its
      associated cardiometabolic disorders in overweight patients. However, studies exploring the
      potential effect of diet's quality or other lifestyle habits (such as physical activity) on
      OSA severity and associated disorders, besides weight loss, are currently lacking. Given that
      a Mediterranean dietary pattern, as well as other lifestyle habits adopted by the populations
      in the Mediterranean region, have been proven beneficial both for the prevention and the
      resolution of the metabolic syndrome and its associated cardiometabolic diseases, the aim of
      the present study is to implement an intervention based on the Mediterranean lifestyle and to
      evaluate its potential beneficial effect on biochemical and clinical characteristics of a
      sample of patients with OSA, compared with standard care. In addition, the superiority of a
      lifestyle intervention based on the Mediterranean lifestyle to a dietary intervention based
      only on the Mediterranean diet will be explored, in order to evaluate possible beyond-diet
      benefits of the health-promoting lifestyle of the Mediterranean that also included reguiar
      physical activity, adequate rest during the day, conviviality, etc.

      This study will be a randomized, controlled, single-blind clinical trial. The study sample
      will consist of adult (18-65 year old), overweight or obese (Body Mass Index > 25 kg/m2)
      patients with moderate or severe OSA (Apnea Hypopnea Index > 15 events/hour) confirmed
      through polysomnography at the Center of Sleep Disorders of the 1st Department of Critical
      Care and Pulmonary Services of "Evaggelismos" General Hospital of Athens. At baseline,
      patients will be informed in detail about the study and will give their written consent.
      Then, subjects will be randomly assigned to one of 3 groups: (a) the control group, receiving
      CPAP therapy and written general advice for a healthy lifestyle, (b) the Mediterranean diet
      group (MDG), participating in a 6-month comprehensive weight-loss dietary intervention based
      on the Mediterranean dietary pattern, and (c) the Mediterranean lifestyle group (MLG),
      receiving the same intensive dietary intervention as the MDG in addition to other healthy
      behaviours incorporated in the traditional lifestyle of the Mediterranean.

      Patients allocated in the two intensive intervention arms will attend a comprehensive
      intervention, comprising seven 60-min group counselling sessions (up to 5 patients per group)
      carried out in the laboratory of Clinical Nutrition & Dietetics of Harokopio University of
      Athens under the supervision of experienced clinical dietitians, conducted every two weeks
      for the first 2 months and every month for the following 4 months until the end of the
      6-month intervention. For both the MDG and the MLG, the intervention will aim at a 5-10%
      weight loss during the 6-month period and an increase in the level of adherence to the
      plant-based Mediterranean diet. Specifically, all food groups of the Mediterranean diet will
      be targeted according to the pattern proposed in the Mediterranean diet pyramid (e.g.
      increase in the consumption of fruits, vegetables, whole grains and legumes, decrease in the
      consumption of red meat and sweets, preference in olive oil as the main source of dietary
      fat, prudent alcohol consumption, etc.), while beneficial culinary practices, as well as
      seasonality and locality of food products consumed, will also be addressed. Patients
      allocated in the MLG will additionally receive counselling on other lifestyle habits, with
      emphasis on adopting a physically active lifestyle and achieving adequate rest during the day
      (both night sleep and siesta nap), as parts of the healthy Mediterranean lifestyle. Dietary
      or lifestyle counselling will be based on the goal setting theory, while motivational and
      behavioural strategies will also be used.

      The assessment of patients' clinical, laboratory and lifestyle characteristics will be
      performed at baseline, at the end of the 6-month intervention and 1 year after the study
      entry at the Center of Sleep Disorders of the 1st Department of Critical Care and Pulmonary
      Services of "Evaggelismos" General Hospital of Athens. The evaluation will include: 1) brief
      medical history assessment, 2) assessment of the severity of the disease through
      polysomnography, 3) evaluation of insomnia through the Athens Insomnia Scale, 4) assessment
      of daytime sleepiness through the Epworth Sleepiness Scale, 5) evaluation of the quality of
      life through the SF-36 questionnaire, 6) dietary assessment through a semiquantitative food
      frequency questionnaire (data from the food frequency questionnaire will be used to evaluate
      participants' food group and individual food and beverage consumption, as well as their
      adherence to the Mediterranean diet through the Mediterranean Diet Score) and 24-hour dietary
      recalls (data from the 24-h dietary recalls will be analysed in terms of energy, macro- and
      micronutrient intake using the Nutritionist Pro, version 2.2 software, as well as of meal
      frequency and patterns), 7) physical activity assessment through the International Physical
      Activity Questionnaire, 8) anthropometric measurements (height, weight, waist and hip
      circumference), 9) blood pressure measurement and 10) fasting blood sample and urine sample
      collection for laboratory measurements (lipid profile, markers of glucose metabolism, markers
      of liver function, inflammatory markers, markers of oxidative stress, etc.) using automated
      analysers and/or commercial ELISA kits.
    

Intervention name(s): Mediterranean lifestyle; Standard care; Mediterranean diet
Intervention type(s): Behavioral; Behavioral; Behavioral
Intervention description(s): Comprehensive 6-month lifestyle intervention (7 60-min group counselling sessions) aiming at promoting adherence to the Mediterranean lifestyle (food and food group consumption according to the Mediterranean diet, beneficial culinary practices, seasonality and locality of foods consumed, socialization during meals, adequate rest during the day through night sleep and siesta nap, sleep hygiene recommendations and adoption of a physically active lifestyle) and at achieving a 5-10% weight loss.; General written instructions regarding the adoption of a healthy lifestyle.; Comprehensive 6-month lifestyle intervention (7 60-min group counselling sessions) aiming at promoting adherence to the Mediterranean dietary pattern (food and food group consumption according to the Mediterranean diet, beneficial culinary practices and seasonality and locality of foods consumed) and at achieving a 5-10% weight loss.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Treatment
Keywords: Sleep Disorders; Metabolic Syndrome; Mediterranean Diet; Mediterranean Lifestyle