Evidence from routinely collected patient data can be used to accurately predict who may experience side effects from methotrexate, the most commonly used immune-suppressing medicine in the UK, researchers have suggested.
Using information that can be readily drawn from electronic health records and during routine consultations, the new findings could allow clinicians to decide how often blood tests should be undertaken to screen for the effects of long-term treatment with methotrexate.
The method, known as ‘risk stratification’, can identify people who may experience blood, kidney, or liver-related side effects due to the medication and would mean patients can safely avoid unnecessary blood tests.
The study, led by the University of Nottingham and funded by the National Institute for Health and Care Research (NIHCR), is published in the BMJ. The researchers hope the findings will improve patients’ lives and save the NHS time and money.
Methotrexate (MTX) is an anti-metabolite most commonly used in chemotherapy and immunosuppressant in auto-immune diseases. Approximately 1.3 million people in the UK are prescribed methotrexate for inflammatory conditions like rheumatoid arthritis and skin conditions, including psoriasis.
Blood tests are carried out every two to four weeks for patients during the first few months of taking methotrexate to monitor for side effects. The tests then change to every three months for all patients. Unnecessary blood tests are a waste of patients’ time and of NHS resources, and previous research has reported that methotrexate side effects were infrequent after the first year of treatment.
The researchers analysed data from 37,109 adults with inflammatory conditions who had been established on methotrexate treatment in a hospital clinic and then prescribed methotrexate by their GP for at least six months. Using part of the data, the researchers developed the risk stratification method to predict the risk of stopping methotrexate treatment for abnormal blood count, liver enzyme level or kidney function over the next five years.
They found that the method could be successfully applied to predict the pattern of side effects in the remaining data. Risk stratification performed well in all age groups across different methotrexate doses and various inflammatory conditions.
The predictions for individual patients taking methotrexate can be worked out using an Excel spreadsheet which can be included in GP electronic health record software to enable an automatic calculator. This would then be ready for use during a consultation and will help GPs and healthcare specialists decide on how best to prioritise the management of their patient’s care and prevent poor health outcomes.
Abhishek Abhishek, Professor of rheumatology at the University of Nottingham, who led the study, said: ‘It is the first study to develop a risk score for predicting these side-effects. The method uses information available during routine consultations at no extra cost and provides individual risk scores that may be used alongside patient preference to decide the interval between monitoring blood-test appointments.’
Currently, the intervals between monitoring blood tests for patients taking methotrexate are decided according to the guidelines issued by relevant specialist societies in the UK, and many patients with inflammatory conditions take methotrexate for over a decade. The researchers hope that the results of this study will enable healthcare specialists to implement risk-stratified monitoring blood tests and reduce unnecessary monitoring blood tests over a long period of time.
The researchers advise that until such recommendations are made, it is essential that patients continue to attend their monitoring blood-test appointments as usual.
Professor Andrew Farmer, director of NIHR’s Health Technology Assessment (HTA) programme, added: ‘High-quality research weighing up the need for tests and treatment are an important part of developing stratified medicine to help improve future health and care practice.’