Effect of Body Mass Index, Metabolic Health and Adipose Tissue Inflammation on the Severity of Non-alcoholic Fatty Liver Disease in Bariatric Surgical Patients: a Prospective Study
Non-alcoholic fatty liver disease (NAFLD), driven by the obesity epidemic, has become the most common form of liver disease. Despite this, there is controversy regarding the prevalence and severity of NAFLD in obesity. Obesity-related factors, such as increasing adiposity, metabolic disease and inflammation, may influence prevalence. We therefore prospectively measured NAFLD prevalence in obesity and studied factors associated with NAFLD.
Materials and methods
We recruited consecutive bariatric patients. Intraoperative liver biopsies were taken. The liver, adipose tissue and serum were collected to measure inflammation. Adipocyte cell size was measured. NAFLD severity was correlated to body mass index (BMI), metabolic health and adipose characteristics.
There were 216 participants; BMI 45.9 ± 8.9 kg/m2, age 44.4 ± 12.1 years, 75.5% female. Overall NAFLD prevalence was 74.1%, with 17.1% having non-alcoholic steatohepatitis (NASH) and/or steatofibrosis. Odds of NASH/steatofibrosis increased independently with BMI category (odds ratio (OR) 2.28–3.46, all p < 0.05) and metabolic disease (OR 3.79, p = 0.003). These odds markedly increased when both super obesity (BMI > 50) and metabolic disease were present (OR 9.71, p < 0.001). NASH/steatofibrosis prevalence was significantly greater with diabetes, hypertension and dyslipidemia. Although greater visceral adipocyte hypertrophy was evident in NASH/steatofibrosis, there was no significant association between adipose inflammation and NASH/steatofibrosis.
NAFLD remains endemic in obesity; however, NASH/steatofibrosis are less common than previously reported. Worsening obesity and metabolic disease increase odds of NAFLD independently, with substantially compounded effect with both. These observations may help with risk stratification in obese populations. We were unable to delineate clear associations between adipose inflammation and NASH/steatofibrosis in this obese population.
Australian Clinical Trials Registry (ACTRN12615000875505).
KeywordsBariatric surgery Obesity Non-alcoholic fatty liver disease Metabolic syndrome Inflammation
Compliance with Ethical Standards
Ethics approval was obtained (Alfred (195/15), Avenue (190) and Cabrini (09-31-08-15) Human Research Ethics Committees).
Conflict of Interest
GJO, PRB, CL and WAB report being affiliated with the Centre for Obesity Research and Education. The Centre has received funding for research purposes from Allergan and Apollo Endosurgery, the manufacturers of the LapBand™. The grant is not tied to any specific research project, and neither Allergan nor Apollo Endosurgery have control of the protocol, analysis and reporting of any studies. The Centre also receives a grant from Applied Medical towards educational programs.
WB reports financial support for a bariatric surgery registry from the Commonwealth of Australia, Apollo Endosurgery, Covidien, Johnson and Johnson, Gore and Applied Medical. Since initial submission of this paper, she has also received a speaker’s honorarium from Merck Sharpe and Dohme and a speaker’s honorarium and fees from participation in a scientific advisory board from Novo Nordisk. The Bariatric Registry and the honorariums are outside of the submitted work.
GJO reports scholarships from the NHMRC and the Royal Australasian College of Surgeons.
MJW is supported by a Senior Research Fellowship from the NHMRC (APP1077703).
The remaining authors have no other disclosures or conflict of interest.
Ethical Approval Statement
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from all individual participants included in the study.
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