NASH – The Silent Killer You’ve Never Heard Of
Posted 12th February 2018 by Jane Williams
Silent killers such as diabetes, high cholesterol and hypertension have been well discussed for many years. While non-medical professionals may not understand the pathophysiology of these diseases, most people can appreciate that they are harmful conditions which require treatment. Worldwide, nonalcoholic fatty liver disease (NAFLD) is estimated to affect more than 1 billion people; so why is nobody talking about it?
The term nonalcoholic steatohepatitis (NASH) was originally coined in the 1980s but research into the condition didn’t heat up for some time. With steatosis historically being labelled a benign condition, many physicians did not perceive NASH to be a threat. The world made great advances in treatments of other liver diseases as the presence of NASH slowly crept up and now it is one of the biggest untapped matters in modern medicine. Set to overtake hepatitis C as the leading cause of liver transplantation by 2020, NASH is a problem that we need to be talking about.
NASH is often asymptomatic and even when symptoms do develop, they are frequently non-specific (malaise, fatigue and vague abdominal pain). When seeing a patient with such symptoms, primary physicians are encouraged to look for hepatomegaly (only present in 5-18% of patients with NAFLD/NASH) and check liver function tests. Although mild to moderate elevation of AST and ALT can be seen in people with NASH, normal laboratory findings do not exclude the condition. To further complicate matters, elevation of these markers does not correlate with the degree of inflammation or fibrosis.
Whilst many physicians use a combination of history, imaging and exclusion of other pathology, the ‘gold standard’ for diagnosis is a liver biopsy. Such procedures can differentiate NAFLD and NASH as well as demonstrate the disease severity. However, this invasive procedure comes with both risks to the patient and cost to the healthcare service. With no clear guidance on who to biopsy, NASH is likely to remain under-diagnosed and thus under-treated.
The rates of obesity, hypertension, dyslipidemia, insulin resistance and diabetes are increasing at an astonishing rate in the western world and it is well known that these conditions are all risk factors for the development of NASH. Much like these silent killers, people with NASH are going about their daily lives feeling absolutely fine. While most governments are trying hard to promote healthy living, if you feel fine then why make a change?
Observational studies in the USA and Europe have shown that half of NAFLD patients are inactive. Although the benefits of exercise are well known to reduce morbidity and mortality in many silent killers, NAFLD patients have low compliance due to high rates of fatigue secondary to existing inactivity.
Over consumptions of fructose, meat, saturated fat and cholesterol coupled with lower consumption of fibre, fish and vitamins all lead to dyslipidemia and insulin resistance. Very few RCTs have looked at dietary interventions on liver injury in NASH but of the small ones that do exist they showed histological improvement with only minimal weight loss. Unfortunately, most large trials on dietary interventions are not applicable; patients often relapse once the intervention is over and physicians cannot sustain the major interventional requirements needed.
We need to talk about NASH…
In 1997 the WHO formally recognised obesity as a global epidemic, but today, rates are increasing faster than ever before. Tackling obesity and its complications (hypertension, dyslipidemia and insulin resistance) have been a public health priority for almost every country, but at times it can feel like a losing battle. NAFLD has a reported worldwide prevalence of up to 35% and this number is only growing. Challenges for the near future include both diagnosis and treatment. There is an urgent need to discover biomarkers which can be used to help diagnose and monitor disease progression.
Alongside this, while multiple therapies are being investigated, weight loss is the only treatment with sufficient evidence suggesting it is both beneficial and safe. New drugs have shown modest results in terms of reduction of hepatic steatosis, inflammation and fibrosis. However, public health prevention strategies are the most important measure. It is vital that health education starts in school and continues into young adulthood.
NASH is a growing global problem but it is never too late to make a difference. The government has the power to change our behaviour. The 2007 public smoking ban in the UK has been tremendously successful in achieving large-scale changes in health. With a growing number of researchers and hardworking healthcare professionals, it is not too late to start tackling NASH.
Dr Michael Gomez is a core medical trainee at the John Radcliffe Hospital in Oxford.
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