A link between Body Mass Index and non-alcoholic fatty liver disease

What was the health challenge?

Non-alcoholic fatty liver disease (NAFLD) is usually a harmless condition of the liver. However, in some people it can proceed to inflammation of the liver which can then lead on to liver cirrhosis. Liver cirrhosis gradually destroys the liver’s cells so that the liver eventually fails.

Body Mass Index (BMI) is a calculation, based on a person’s weight and height, to measure the extent to which someone is overweight or obese. A link between obesity and NAFLD has been assumed for many years because of findings from research studies involving small numbers of patients. There has been no large-scale research studying the distribution and patterns of what levels of BMI are linked to NAFLD.

What was the purpose of the research?

The purpose of this study was to better understand the link between BMI and NAFLD. It was conducted by a collaborative team of research scientists from the British Heart Foundation, the University of Glasgow, Pfizer and GlaxoSmithKline.

Why and how was health data used?

Using databases that contain large amounts of anonymised patient data it was possible to conduct research into the link between BMI and NAFLD. Large patient numbers are needed to study which people with different BMI levels over time do eventually develop NFALD, and which do not. Starting with databases containing data on over 30 million patients, the research eventually studied the records of just over 2 million patients who had the necessary data recorded in the database, and who did not have other conditions that would affect BMI or NAFLD.

Two large anonymised health databases were used in the research - the Health Improvement Network (THIN) database (UK) and the Humedica database (US). The data in these databases contained routinely collected patient data from GPs, specialty care and hospitalisations in the years of 2007–2013, which had been carefully anonymised.

What was the legal basis for using the data?

The European General Data Protection Regulation (GDPR) does not require a legal basis if the health data have been anonymised.

What were the results?

The results showed that there was a continuous and strong link between a rising BMI and the diagnosis of NAFLD. The link was stronger for men and for people with diabetes.

What was the benefit to patients and healthcare systems?

This information is useful for patients, public health organisations and clinicians when considering preventative health measures to reduce the likelihood of NAFLD for those patients who are overweight or obese.

Further information

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