Millions of people with rheumatoid arthritis and psoriasis could benefit from Nottingham biomarker research.

Nottingham researchers found its side effects are less likely than previously thought and are calling for guidelines affecting the use of methotrexate to be reviewed.

Doctors have used the immuno-suppressant since 1947 and around 1.3 million people in the UK are prescribed it. However, long term use was limited because it was thought to increase liver scarring in about 5 percent of patients, which can increase the chances of chronic conditions such as type 2 diabetes, heart and circulatory disease.

The new study, published in the Journal of Hepatology, compared 1000 patients over seven years. Three quarters took methotrexate and one quarter did not and researchers compared biological markers which indicate liver scarring in the two groups.

They found that levels of scarring in the methotrexate group were less than expected based on previous assumptions, and suggest that older studies did not differentiate methotrexate from other factors such as type 2 diabetes, age, and weight which on their own could be the reason for liver scarring.

Chief investigator Professor Guruprasad Aithal said: “We know methotrexate helps to reduce inflammation caused by the body’s immune system not working properly, but earlier studies seemed to show it could also damage liver over a long period, so patients have needed monitoring with regular blood tests.

“This research means the risks are lower, so many more people could be safely prescribed this drug without such an intensive monitoring with blood tests, and get the benefit of the medication such as reduced joint pain and skin rashes. We want the treatment guidelines for methotrexate to be reviewed.”

The study was funded by the National Institute of Health and Care Research Nottingham Biomedical Research Centre and Innovative Medicines Initiative 2 of the European Union and the European Federation of Pharmaceutical Industries & Associations (EFPIA): TransBioLine.

The results are published in the Journal of Hepatology.