In the gruesome Greek myth, Prometheus's liver is pecked out daily by an eagle, only to regenerate overnight. In the real world, the liver's capacity for self-repair is indeed an extraordinary feature, but there are limits. The topic of this blog is the harm and injury from which the liver can't necessarily recover.
There are many different types of liver disease, of which cirrhosis is one of the most serious. Cirrhosis is a form of scarring in the liver caused by long-term damage that can increase the risk of liver cancer. In England, liver disease is the third leading cause of early death, after cancer and cardio-respiratory disease. In 2010, it accounted for 141,600 potential years of life lost. It tends to kill people at a younger age, on average, than other chronic diseases.
Over the past twenty years, cirrhosis has jumped from eighth to third place as a cause of years of life lost for people aged 20-54. As death rates from liver disease have risen, so too have the incidence and the mortality from primary liver cancer (cancer which starts in the liver).
The increase in death rates from liver disease in middle-age is particularly worrying, especially given that death rates from the problem are falling across Europe. Since we've succeeded in improving mortality for many other diseases, most notably for cardiovascular disease, why can't we get the trends moving in the right direction for liver disease?
After all, the main risks that lead to liver disease (excessive alcohol consumption, infection from Hepatitis B and C, and, increasingly obesity) are preventable and treatable. In this blog, I'll focus on the non-infectious causes, but in reality, there isn't a strict dividing line: for example, alcohol harms people with alcohol-related cirrhosis as well as those whose liver disease is of infectious origin.
In England, most premature mortality from liver disease over recent decades was due to alcoholic liver disease. That's not surprising given the increase in alcohol consumption per person over the past half century. It's true that there've been falls in consumption most recently, but we're likely to see a continued rise in the burden of liver disease for some time yet because it takes so long for liver damage to produce symptoms.
What's encouraging is that even small reductions in risks, such as alcohol consumption, can reduce the likelihood and severity of liver disease, in some cases even reversing its damaging effects. Lower alcohol consumption would yield many other health benefits at population level (for example for some cancers) as well as broader social and economic benefits.
Getting there will be a collective effort. There are many resources available to support individuals to reduce their alcohol consumption, ranging from online tools to visiting their GP. But risk behaviours, from alcohol to smoking, are shaped and influenced by our wider environment: our social networks, the stresses in our lives, where we live and work. When communities come together to take action against harmful alcohol use, they can support individuals to make healthier choices. In Brighton and Hove, stakeholders including universities, off-licences and bars, the voluntary sector, the NHS, the police and the council through its many departments (including public health, housing and environmental health) are part of a major alcohol strategy, focused on the drinking culture, the night-time economy, the availability of alcohol and treatment of alcohol disorders. It's hard to prove cause and effect, but the council says alcohol-related crime and hospital admissions have been falling over the past five years.
Local authorities play a key role because they have new responsibilities for public health, but so too does national government, through the many levers it can pull to create an environment that promotes health (from alcohol pricing to smoking restrictions). The role of public health is to highlight the evidence for the most effective interventions and to focus efforts on meeting the biggest challenges.
One of these is reducing the prevalence of excess weight and obesity. This links into liver disease because obesity is a major risk factor for a common form of liver disease: non-alcoholic fatty liver disease (NAFLD).
This type of liver disease may be harmless in many people, but in some it can lead to more serious forms, ultimately causing cirrhosis and even liver cancer. There's been a big increase in the number of hospital admissions for NAFLD in England over the past 15 years, which is likely to be linked to the rise in obesity. There's still a lot we don't know about NAFLD (and better data would help us understand it better), but it does seem that, as with so many other chronic diseases, we need to be thinking about clusters of risks: a large proportion of people with NAFLD also have high blood pressure and also have type 2 diabetes. Promoting weight loss to treat NAFLD would help manage these other chronic conditions as well.
The obesity problem is complex. As with alcohol, it will take many different types of actions to shift the levels of obesity across the population. We've got to support people to make healthier choices in what they eat and how much they exercise through changing the web of environmental factors that push us towards unhealthy lifestyles. From town planning to transport, school food to restrictions on fast food outlets, local authorities can take action to tackle the obesity epidemic.
Just as importantly, we can take action as individuals, by investing in our own health and that of our families. We know that the same things that help to protect our liver also protect our overall health and wellbeing. So by choosing better diets, getting more exercise, not smoking and drinking within guidelines, we're also choosing to reduce our risk of disease. Changing behaviours is difficult, which is why the Change4Life campaign helps make it more manageable: with ideas for swapping sugary drinks to "sugar-free" or lower fat milk or water, for example, or with fun ideas for bursts of activity to get children moving more. We owe it to ourselves to be aware of how and when our habits could become harmful and ask for help if it's needed, whether it's to stop smoking or to lose weight.
If there's one overarching message, it's that liver disease can often be prevented and treated. The tragedy is that the early stages may slip by unnoticed because of a lack of symptoms. For example, less than 20% of primary liver cancer is detected at a stage where treatment could potentially cure a person.
The Lancet recently launched a Commission to investigate the high mortality and poor quality of life of patients with liver disease in the UK. Effective, evidence-based public health measures have a key role to play in ensuring we have a better story to tell on liver disease in the future.