Anesthetic Methods and Gene Expression Profile
Condition: Hip Arthroplasty
Study type: Observational

Summary: 
      The study will analyze differentially regulated genes involved in oxidative stress and
      toxicology in peripheral blood mononuclear cells (PBMCs) of patients who underwent
      arthroplasty under three different anesthetic methods. The investigator hypothesized that
      anesthesia procedures trigger toxicity, thus inducing changes in the messenger ribonucleic
      acid (mRNA) profile. The results may provide a more profound understanding of the molecular
      mechanism of anesthesia and in overcoming the adverse effects arising from their use.
    

Detailed description: 
      By using a computer-generated randomization table, hospitalized patients undergoing elective
      hip arthroplasty will be randomly consecutively allocated to receive general (GA group),
      regional (RA group), or integrated (IA group) anesthesia. Patients with contraindication to
      spinal anesthesia or lumbar catheter placement, as well as obese patients, with arterial
      hypertension not controlled by oral medication, severe pulmonary, cardiovascular, renal,
      hepatic, cerebrovascular, or psychiatric diseases will be excluded from the study.

      Whole blood samples (10 mL) will be obtained from all enrolled patients at three time points:
      early morning on the operation day (T0), after surgery (T1) and third day (T2) after surgery.
      The samples will be collected in heparin tubes and PBMCs will be isolated and used for gene
      expression analysis. Serum obtained after blood centrifugation will be used for hematological
      and biochemical analysis such as glutamate oxaloacetate transaminase (GOT),
      glutamate-pyruvate transaminase (GPT), bilirubin (BIL), creatinine (CREA), creatine
      phosphokinase (CPK), hemoglobin (HB).

      The sample size was determined according to Lee- Whitmore * and G*Power Ftest for ANOVA Fixed
      effects, omnibus, one-way (Lee ML, Whitmore GA. Stat Med. 2002;21: 3543-3570). Assuming a
      Poisson distribution for the expected value of the false-positive gene expression of the 9
      chosen genes and fixing at 1 the maximum expected value for false positives E(R0) and
      considering all the 84 genes as not differentially expressed (G0=G=9), the probability α for
      any single gene among the G genes that are not differentially expressed is given by α=E(R_0
      )/G=1/9=0.011, with the Bonferroni correction it becomes α_c=(0.011)/3=0.037. This is the
      type I error of a false positive expression. Moreover, considering as primary endpoint the
      fold increase of the gene expression, assuming a log-normal distribution with standard
      deviation of 0.7 which is typical of moderate-high gene expression and therefore a
      conservative one for the sample size determination and imposing a minimum difference on
      logarithmic scale among the 3 groups of 0.5 with a power of at least 0.8 and a Bonferroni
      corrected type I error α=0.05/3=0.0167 (which is smaller and then conservative, than the
      previous α_c) the minimum sample size(G*POWER)^ for each group is 30 patients, by considering
      a 10% of drop-out , the chosen sample size was 33 patients per group which leads to a total
      sample size of 99 patients.

      ^F tests - ANOVA: Fixed effects, omnibus, one-way Analysis: A priori: Compute required sample
      size Input: Effect size f = 0.7 α err prob = 0.0167 Power (1-β err prob) = 0.8 Number of
      groups = 3 Output: Noncentrality parameter λ = 14.7000000 Critical F = 4.7803455 Numerator df
      = 2 Denominator df = 27 Total sample size = 30 Actual power = 0.8009945

      The normal distribution of continuous variables will be evaluated by Kolmogorov-Smirnov test.
      The Chi-square test will be used to evaluate categorical variables. The differences between
      groups will be evaluated by means of parametric ANOVA tests followed by Tukey test. Multiple
      regression analysis will be performed to evaluate the influence of biochemical parameters on
      gene expression in response to anesthetics considering confounding factors such as age,
      gender, BMI, smoking. Values of p <0.05 will be considered statistically significant. All
      tests will be performed using software (SPSS, Chicago, USA).
    

Intervention name(s): hip arthroplasty
Intervention type(s): Procedure
Intervention description(s): Hip replacement is a surgery for people with severe hip damage. The most common cause of damage is osteoarthritis.
Other intervention name(s): Hip prosthesis
Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        patients undergoing elective hip arthroplasty
      
Biospecimen description: 
      Whole blood samples will be obtained from all enrolled patients. The samples will be
      collected in heparin tubes and peripheral blood mononuclear cell (PBMC) fraction will be
      isolated for total RNA extraction.
    
Keywords: General anesthesia; Regional anesthesia; Integrated anesthesia; Hip arthroplasty; Toxicological gene expression