Body Fat Mass Association With Clinical Metabolic Profiles, Markers of Inflammation and Adipocytokines
Condition: Overweight and Obesity
MeSH terms: Overweight; Inflammation
Study type: Observational

Summary: 
      Overweight and obesity have become an increasing problem in patients on hemodialysis.
      However, in virtually all observational studies in chronic kidney disease(CKD) and dialysis
      patients , using body mass index(BMI) as metric fat mass is associated inversely with death
      rate. Nevertheless, it is questionable that obesity can be considered an unequivocal
      protective factor in chronic diseases as increase body fat mass appears to be a potential
      cause of the chronic inflammation frequently present in these patients. The consequences of
      this inflammation are impaired nutritional status, accelerated atherosclerosis, and increased
      mortality. In the present study, by using dual-energy X-ray absorptiometry (DEXA) and
      bioimpedance spectroscopy (BIS) to evaluated the contributions of fat mass to outcomes in an
      observational cohort of hemodialysis patients. Besides, we aim to assess the relationship
      between body fat composition, clinical metabolic risk profiles, measures of adiposity, such
      as waist circumference (WC), visceral adiposity index, waist-to-hip ratio (WHR), and
      waist-to-height ratio (WHtR), markers of inflammation and adipocytokines in these maintenance
      hemodialysis patients.
    

Detailed description: 
      Patient Selection

      Clinically stable stage 5 chronic kidney disease patients (400 patients) attending the Tungs
      Taichung Metroharbour will be enrolled in this study. These patients will be given written
      information and are invited to participate in the study. Written informed consent will be
      obtained from each patient enrolled. Our hospital dialysis center undergoes multi-frequency
      bioelectrical impedance analysis( BIA) scanning on a bimonthly basis as part of their ongoing
      clinical care. Multi-frequency BIA is performed on patients attending the center as part of
      their routine dry weight assessment. Among these patients, eighty ambulatory adults attending
      for thrice-weekly outpatient hemodialysis treatments concomitantly had similar dual-energy
      X-ray absorptiometry (DEXA) scan and postdialysis multi-frequency BIA assessments for review.
      Patients with implantable defibrillators, those with cardiac pacemakers, and amputees are
      excluded from the study. This study will be conducted prospectively for 3 years.

      Methods Body Composition Assessment Measurements with dual-energy X-ray absorptiometry (DEXA)

      DEXA was performed with patients in the supine position. The radiation exposure is estimated
      to be one tenth of that for standard chest radiography. DEXA is scheduled postdialysis.
      Whole-body composition, including total and segmental lean, total body fat mass, and bone
      mineral content, will be calculated using the compatible software. For patients with multiple
      multifrequency BIA estimations, the study performed will be arranged temporally to the DEXA
      scan for more relevant comparison.

      Measurement of Bioimpedance In all patients BIS will be carried out bimonthly using the Body
      Composition Monitor (Fresenius Medical Care Deutschland Gesellschaft mit beschrankter Haftung
      (GmbH), Germany), which takes measurements at 50 frequencies in a range of 5 to 1000
      kilohertz(KHz). The measurement was performed approximately 30 minutes after the midweek
      hemodialysis session, with four conventional electrodes being placed in the patient, who was
      lying in the supine position: two in the hand and two in the foot contralateral to the
      vascular access. Regarding the quality of measurements, all exceeded 95%. The manufacturer of
      the Body Composition Monitor (Fresenius Medical Care) indicated that 30 minutes after the
      hemodialysis session, the balance between intra-and extracellular fluid was restored and no
      significant differences in relation to pre-dialysis values were observed. Parameters obtain
      directly through BIS that are used in this study are free fat mass, lean body mass,
      intracellular water (ICW) and extracellular water( ECW). Protein-energy wasting (PEW),
      represented by the intracellular water/dry body weight (ICW/BW) ratio, and overhydration,
      represented by the extracellular water/dry body weight(ECW/BW) ratio will be analysed.

      Anthropometric parameters The following data will collected bimonthly : height (m)), dry
      weight (kg) measured with a calibrated scale and body mass index(BMI,kg/m2). Abdominal
      obesity is defined as a waist circumference of >80 cm in women and >90 cm in men.

      Biochemical assays and other measurements Fasting blood samples (4 ml each time) were taken
      just before starting a dialysis session.The vacutainers were kept cold and placed immediately
      on ice, then they were centrifuged at 4 degree centigrade and the serum was stored at -80
      degree centigrade until the analysis. The measurements of serum creatinine, cholesterol,
      total proteins, albumin, prealbumin and carbon dioxide(CO2) were analysed using standard
      methods. Urea reduction ratio and single-pool dialysis efficiency calculator(Kt/V) were used
      to represent the administered dialysis treatment dose. To decrease intraindividual variation,
      3-month averaged values for laboratory measures and urea reduction ratio during the study
      calendar quarter were calculated and used in this study. High sensitivity C- reactive
      proteins(CRP) was obtained by the immuno-turbidimetric method. Serum 25(OH)D3 was measured by
      enzymeimmunoassay and the levels of intact parathyroid hormone( i-PTH) were assessed using
      immunoradiometric assay. Plasma insulin levels were measured using a radioimmunoassay method.
      Interleukin-6(IL-6) and tumor necrosis factor-alpha (TNF-α) concentrations were measured in
      duplicate by enzyme-linked immunosorbent assay(ELISA). Insulin resistance was assessed using
      the following validated formula: homeostasis model assessment of insulin resistance
      (HOMA-IR)=(fasting glucose [mmol/1] × fasting insulin [μU/ml])/22.5. Because of confounding
      introduced by exogenous insulin administration to HOMA-IR results, HOMA-IR was only measured
      in patients who were not treated with insulin . All the above measurements will be done at
      baseline, and the end of each years (4 times for the whole study)
    

Observational model: Case-Crossover
Time perspective: Cross-Sectional
Sampling method: Non-Probability Sample
Study population: 
        hemodialysis (HD) patients
      
Keywords: Fat mass; hemodialysis patients; inflammation; adipocytokines; bioimpedance spectroscopy