54 Sample size determination Studys hypothesis is superiority of intervention

54 sample size determination studys hypothesis is

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5.4 Sample size determination: Study’s hypothesis is superiority of intervention arm (probiotic) over control (placebo). Calculations were performed in the WINPEPI program (compare 2, means comparison). Table no. 2 : Sample size calculation by HRI Main variable difference between arms SD in each arm Β (power) α (Significance level) N (sample size) HRI ***0.55 **0.75 0.8 0.05 62 (31 in each arm, 0% dropout) ** In a sample of the Israeli population the mean HRI was 1.65±0.75 (0.88-3.78) (32). *** HRI decrease of 0.55 is clinically significant for NAFLD patients since it is the average of the decrease by 2 levels (highest level of steatosis to lowest) or one level of the index (32). * Adding 20% dropout from the study will end in 38 patients in each arm. * There will be 2 arms of treatments (probiotic vs. placebo) -50 patients in each arm - 1 00 patient total . 8
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Version 5/4.5.14 5.5 Randomization: The most accepted and reliable methodology for reducing unwanted bias in clinical trials is the randomization technique (33). There are many randomization methods that are known to effectively maintain allocation concealment; however most are complex and expensive (33). When conducted properly, randomizing participants using sequentially numbered, opaque sealed envelopes (SNOSE) is the most accessible and straightforward method of maintaining allocation concealment and it does not require the use of specialized technology (33). In this study patients will be randomized to 2 arms (probiotic vs. placebo) using the SNOSE method according to Doig et al (33). 5.6 Major outcome variables: The measurements will be tested preoperatively (MO), 3 (M3), 6 (M6) and 12 (M12) months postoperatively ( See Appendix 3 for visit schedule and assessments). 5.6.1 Anthropometric evaluation: Measurements of anthropometry (Height, weight and WC) will be performed following a uniform protocol at M0, M3, M6 and M12. BMI will be calculated by the equation weight divided by square height. WC will be measured at the level of the umbilicus. %EWL will be calculated as follows: [(preoperation weight-postoperation weight)/(preoperation weight-ideal weight)]x100. Ideal weight is considered as the weight for BMI 25 kg/m² (34). “Tanita” will be used for body composition analysis (%fat mass, fat mass and fat free mass) and will be performed at M0 and M6. 5.6.2 Biochemical tests: Patients will undergo biochemical tests at MO, M3, M6 and M12. All blood samples will be drawn at the morning after a fast of at least 12 hours. All biochemical assessments will be performed by the same laboratory, Sourasky hospital Laboratory, and using the same standard laboratory methods. Serological tests that will be taken: Total cholesterol (TC), Low density lipoprotein cholesterol (LDL-C), High density lipoprotein cholesterol (HDL-C), Triglycerides (Tg), LPS , inflammatory factors (CRP, TNF-α, IL6, IL10, TGF- β), adipocytokines (leptin, adiponectin), hepatocyte apoptosis markers (CK-18, sFas), glucose, HbA1C, total bilirubin, total bile acids, liver enzymes, Thyroid-stimulating hormone (TSH), fasting insulin, vitamin B1, vitamin B12, vitamin D, Iron, ferritin, folic acid. HOMA is
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  • Fall '16
  • Jeff Miller

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