Conference Paper

Effects of short-term energy restriction prior to bariatric surgery on liver fat, inflammation and systemic metabolic parameters. Diabetes UK 2015 (London)

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Abstract

Aims: To compare the effects of two very low energy dietary regimens on liver fat, inflammation and systemic metabolic parameters in severely obese adults prior to undergoing bariatric surgery. Methods: We conducted a prospective randomised clinical trial at the Royal Derby Hospital May 2012-June 2014, comparing outcomes of two energy restrictive regimens applied over two weeks, 1) food-based diet, 2) meal replacement plan (provided by LighterLife). Clinical and anthropometric information and fasting blood were collected pre and post diet, and a liver biopsy obtained during surgery. Results: Of 60 participants recruited 54 completed the study, food-based diet n=26, meal replacement plan n=28. Diet groups matched demographically; overall 81.5% female, median age 45 years, median body mass index (BMI) pre-diet 50.7kg/m2, 30% with Type 2 diabetes. Reported daily energy intake (median 715kcal/d) and body weight loss achieved (median 3.4%) were similar between groups. However, percentage of energy intake from carbohydrate, fat and protein were significantly different between groups. Circulating cholesterol, NEFA, CRP, Fetuin-A, and leptin all changed significantly in both diet groups; however IL6, triglycerides and glucose only changed significantly after the meal replacement plan. On liver biopsy, significant associations were found between diabetes status/impaired fasting glucose and histological grade of steatosis, lobular inflammation and non-alcoholic fatty liver disease (NAFLD) activity score. Conclusions: Both diet groups achieved significant weight loss prior to bariatric surgery; however the meal replacement plan achieved greater modification in circulating biomarkers. Patients with Type 2 diabetes or impaired fasting glucose had greater severity of NAFLD on histology.

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Background: The prevalence of nonalcohol-related fatty liver disease (NAFLD) varies between 19% and 33% in different populations. NAFLD decreases life expectancy and increases the risks of liver cirrhosis, hepatocellular carcinoma, and requirement for liver transplantation. There is uncertainty surrounding the relative benefits and harms of various lifestyle interventions for people with NAFLD. Objectives: To assess the comparative benefits and harms of different lifestyle interventions in the treatment of NAFLD through a network meta-analysis, and to generate rankings of the different lifestyle interventions according to their safety and efficacy. Search methods: We searched CENTRAL, MEDLINE, Embase, Science Citation Index Expanded, Conference Proceedings Citation Index - Science, World Health Organization International Clinical Trials Registry Platform, and trials registers until February 2021 to identify randomised clinical trials in people with NAFLD. Selection criteria: We included only randomised clinical trials (irrespective of language, blinding, or status) in people with NAFLD, whatever the method of diagnosis, age, and diabetic status of participants, or presence of non-alcoholic steatohepatitis (NASH). We excluded randomised clinical trials in which participants had previously undergone liver transplantation. Data collection and analysis: We planned to perform a network meta-analysis with OpenBUGS using Bayesian methods and to calculate the differences in treatments using hazard ratios (HRs), odds ratios (ORs), and rate ratios (RaRs) with 95% credible intervals (CrIs) based on an available-participant analysis, according to National Institute of Health and Care Excellence Decision Support Unit guidance. However, the data were too sparse for the clinical outcomes. We therefore performed only direct comparisons (head-to-head comparisons) with OpenBUGS using Bayesian methods. Main results: We included a total of 59 randomised clinical trials (3631 participants) in the review. All but two trials were at high risk of bias. A total of 33 different interventions, ranging from advice to supervised exercise and special diets, or a combination of these and no additional intervention were compared in these trials. The reference treatment was no active intervention. Twenty-eight trials (1942 participants) were included in one or more comparisons. The follow-up ranged from 1 month to 24 months. The remaining trials did not report any of the outcomes of interest for this review. The follow-up period in the trials that reported clinical outcomes was 2 months to 24 months. During this short follow-up period, clinical events related to NAFLD such as mortality, liver cirrhosis, liver decompensation, liver transplantation, hepatocellular carcinoma, and liver-related mortality were sparse. This is probably because of the very short follow-up periods. It takes a follow-up of 8 years to 28 years to detect differences in mortality between people with NAFLD and the general population. It is therefore unlikely that differences by clinical outcomes will be noted in trials with less than 5 years to 10 years of follow-up. In one trial, one participant developed an adverse event. There were no adverse events in any of the remaining participants in this trial, or in any of the remaining trials, which seemed to be directly related to the intervention. Authors' conclusions: The evidence indicates considerable uncertainty about the effects of the lifestyle interventions compared with no additional intervention (to general public health advice) on any of the clinical outcomes after a short follow-up period of 2 months to 24 months in people with nonalcohol-related fatty liver disease. Accordingly, high-quality randomised clinical trials with adequate follow-up are needed. We propose registry-based randomised clinical trials or cohort multiple randomised clinical trials (a study design in which multiple interventions are trialed within large longitudinal cohorts of participants to gain efficiencies and align trials more closely to standard clinical practice), comparing aerobic exercise and dietary advice versus standard of care (exercise and dietary advice received as part of national health promotion). The reason for the choice of aerobic exercise and dietary advice is the impact of these interventions on indirect outcomes which may translate to clinical benefit. The outcomes in such trials should be mortality, health-related quality of life, decompensated liver cirrhosis, liver transplantation, and resource use measures including costs of intervention and decreased healthcare use after a minimum follow-up of eight years, to find meaningful differences in the clinically important outcomes.
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