Resting Energy Expenditure in Patients on the Waiting List for Liver Transplantation
Condition: Liver Disease; Cirrhosis
MeSH terms: Liver Diseases
Study type: Observational

Summary: 
      Metabolic disorders and malnutrition are well known and have been reported in patients with
      chronic liver disease, but the relationship of energy metabolism and changes in nutritional
      status in patients on the waiting list for liver transplantation are unexplored. The aim of
      this study was to assess the resting energy expenditure (REE) of these patients, identifying
      the prevalence of hyper and hypometabolism. In addition, to assess if, malnutrition and
      clinical variables were associated with REE and metabolic disorders.
    

Detailed description: 
      This cross-sectional and descriptive study was carried out at the Alfa Institute of
      Gastroenterology, Hospital of Clinics, Universidade Federal of Minas Gerais (UFMG). The
      research protocol was approved by the UFMG Ethics Committee. Patients with indication for
      liver transplantation, aged over 20 years who regularly attended the Liver Outpatient
      Transplant Clinic were included after having agreed and signed the informed consent form. The
      presence of endocrine abnormalities (hyper/hypothyroidism) and patients on the waiting list
      for a double or re-transplant were excluding conditions. The REE and nutritional status
      assessment were performed by the same trained investigator (LGF) in order to reduce errors.

      Resting Energy Expenditure - REE was measured by indirect calorimetry using a gas analyzer
      K4b2 (Cosmed, Rome, Italy). The test was performed in a silent, temperature-controlled room
      (22-24oC) in the morning, between 08:00am and 09:30am. The patients fasted for 12 hours, and
      remained on the lying position for about 20 minutes before the beginning of the test. The
      device was calibrated before each exam. The volume of inspired oxygen (VO2) and exhaled
      carbon dioxide (VCO2) was collected through a turbine and a sample line, adapted to the face
      mask, applied to the patient and, connected to the unit. The collection of gases occurred for
      25 minutes, and the first 5 minutes were discarded. The mean VO2 and VCO2 per minute were
      used to calculate the REE according to the Weir formula. The obtained data were multiplied by
      1,440 to obtain the 24-hour REE. Therefore, the REE was divided by kilograms of fat free mass
      - FFM (REE/FFM). Predicted REE was calculated from the Harris and Benedict formula (REEHB).
      In patients with fluid retention (clinical evidence of ascites and/or limb edema) dry weight
      was calculated by deducting an estimated weight for ascites and/or limb edema. Hypermetabolic
      patients were identified if the ratio REE:REEHB was > 120% and hypometabolic patients were
      classified according to the ratio REE:REEHB < 80%. The non-protein respiratory quotient (RQ)
      was calculated by the formula VCO2/VO2. Oxidation rates of carbohydrate and fat were
      expressed as percentages of total generated energy.

      Nutritional Assessment - Nutritional status was provided by the Subjective Global Assessment
      (SGA), anthropometric measurements, handgrip strength, bioimpedance and energy balance (EB)
      analyses. The SGA adapted for patients on the waiting list for liver transplantation is based
      on clinical history and physical examination, as well as the presence of existing conditions
      such as encephalopathy, chronic or recurrent infection, varicose veins and renal function.
      Patients were classified as nourished and those classified as suspected or moderately
      malnourished and severely malnourished were grouped together to form the malnourished group.

      Anthropometric evaluation was comprised of weight, height, body mass index (BMI), triceps and
      subscapular skinfold thickness (TSF and SSF respectively, measured with the Lange Skinfold
      Caliper - Cambridge Scientific Industries Inc., Cambridge, MD, USA), midarm circumference
      (MAC, measured with inextensible tape), arm muscle area (AMA) and arm fat area (AFA). To
      minimize practical variability, the average of three consecutive measurements was recorded.
      Values of TSF, SSF, MAC, AMA and AFA below the 5th percentile and BMI below 18.5kg/m2 (or
      22.0kg/m2 for elderly) were considered as malnutrition.

      Handgrip strength (HS) was assessed with the Jamar Handgrip Dynamometer (Preston, Jackson,
      MI, USA) using the non-dominant arm, and the mean of three measurements was determined.
      Malnutrition was defined as values of HS below the 5th percentile.

      Bioelectrical impedance analysis (Quantum X - RJL Systems, Inc., Clinton Township, Michigan)
      was used to determine body composition. Measurements were made with patients lying in bed
      with 4 electrodes attached to the dorsum of the right hand and foot. Phase angle (PA), fat
      mass (FM - kg), fat free mass (FFM, kg), total body water (TBW - L), intracellular water (ICW
      - L) and extracellular water (ECW - L), were evaluated. PA was categorized in equal to or
      less than 5.4o, or above 5.4o as proposed by Selberg et al.

      The energy balance (EB) was obtained by subtracting the total energy expenditure from the
      total caloric intake (TCI). The TEE was obtained by multiplying the 24-hour REE by the
      calculated activity factor (AF), which was based on the description of the patients' daily
      activities and the corresponding computed values of metabolic equivalents (METs). Food intake
      was assessed by a 3-day food record (DietPro5i® Agromídia Software, Viçosa, Brazil).

      Clinical and other variables - Age, sex, etiology, severity of liver disease by the
      Child-Pugh score (22) and the Model for End Stage Liver Disease score (MELD), complications
      like presence of fluid retention and hepatic encephalopathy; number of medication and
      diuretics; β-blockers and lactulose use were all compiled. Diagnosis of liver cirrhosis was
      based of clinical, biochemical and histopathological data. The indications for liver
      transplantation were categorized into alcoholic cirrhosis, viral and other diseases. Liver
      function tests (aspartate aminotransferase - AST, alanine aminotransferase- ALT, total
      bilirubin-TB and international normalized ratio-INR), presence of diabetes and/or glucose
      intolerance (24) and fasting glucose were also investigated.
    

Observational model: Case-Only
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Patients on the waiting list for liver transplant
      
Keywords: Resting metabolic rate; nutrition status; dietary intake