Systematic review: the epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults

Authors

  • G. Vernon,

    1. Department of Medicine, Center for Liver Diseases, Inova Fairfax Hospital, Falls Church, VA, USA.
    2. Betty and Guy Beatty Center for Integrated Research, Inova Health System, Falls Church, VA, USA.
    Search for more papers by this author
  • A. Baranova,

    1. Betty and Guy Beatty Center for Integrated Research, Inova Health System, Falls Church, VA, USA.
    2. School of Systems Biology, College of Science, George Mason University, Fairfax, VA, USA.
    Search for more papers by this author
  • Z. M. Younossi

    1. Department of Medicine, Center for Liver Diseases, Inova Fairfax Hospital, Falls Church, VA, USA.
    2. Betty and Guy Beatty Center for Integrated Research, Inova Health System, Falls Church, VA, USA.
    Search for more papers by this author

  • This uncommissioned systematic review was subject to full peer-review.

Dr Z. M. Younossi, Center for Liver Diseases, Inova Fairfax Hospital, 3300 Gallows Road, Falls Church, VA 22042, USA.
E-mail: zobair.younossi@inova.org

Abstract

Aliment Pharmacol Ther 2011; 34: 274–285

Summary

Background  Non-alcoholic fatty liver disease (NAFLD) is a common cause of chronic liver disease, and its worldwide prevalence continues to increase with the growing obesity epidemic. This study assesses the epidemiology of NAFLD in adults based on clinical literature published over the past 30 years.

Aim  To review epidemiology and natural history of non-alcoholic fatty liver disease and non-alcoholic steatohepatitis in adults based on clinical literature published over the past 30 years.

Methods  An in-depth search of PubMed (1980–2010) was based on five search terms: ‘non-alcoholic fatty liver disease’ OR ‘non-alcoholic steatohepatitis’ OR ‘fatty liver’ OR ‘steatosis’ AND ‘incidence’ [MeSH Terms] OR ‘prevalence’ [MeSH Terms] OR ‘natural history’. Studies of paediatric cohorts were excluded. Articles were categorised by topic and summarised, noting generalisations concerning their content.

Results  Four study categories included NAFLD incidence, prevalence, risk factors and natural history. Studies related to NAFLD prevalence and incidence indicate that the diagnosis is heterogeneous and relies on a variety of assessment tools, including liver biopsy, radiological tests such as ultrasonography, and blood testing such as liver enzymes. The prevalence of NAFLD is highest in populations with pre-existing metabolic conditions such as obesity and type II diabetes. Many studies investigating the natural history of NAFLD verify the progression from NASH to advanced fibrosis and hepatocellular carcinoma.

Conclusions  Non-alcoholic fatty liver disease is the most common cause of elevated liver enzymes. Within the NAFLD spectrum, only NASH progresses to cirrhosis and hepatocellular carcinoma. With the growing epidemic of obesity, the prevalence and impact of NAFLD continues to increase, making NASH potentially the most common cause of advanced liver disease in coming decades.

Ancillary