More research needed
The research involved “incredibly sophisticated statistical analysis,” said Daniel E. Furst, MD, professor emeritus of medicine at the University of California, Los Angeles, who was not involved with the study. However, the data do not yet support altering blood testing frequency based on this model.
Dr. Daniel E. Furst
“The hypothesis that not all patients have to be examined so frequently is a very reasonable hypothesis,” Dr. Furst said in an interview, and additional research is needed to corroborate it. The model also needs to be validated in patient populations outside of the United Kingdom, he added.
Dr. Abhishek agreed that validating the model in other patient populations is an important next step. “When we develop a tool [using] a one-nation data set, we want other researchers to then validate it in other countries’ data sets to make sure there is nothing odd about patients in the U.K. that makes the tool work well here but not in [the] U.S., Europe, or Asia, for example,” he said. Doing so should be relatively easy, he said, as the model is publicly available, and the information required is routinely collected during clinic visits.
To understand if less frequent testing might be appropriate for some patients, researchers would need to look at data registries like the Brigham and Women’s Hospital Rheumatoid Arthritis Sequential Study (BRASS) registry or CorEvitas registries “where the testing is done in a very regular way over the long haul,” Dr. Furst said. Analyzing these datasets, researchers could determine the testing intervals that would be most efficient for low- and high-risk patients.
A word of caution
While less frequent testing for long-term MTX therapy could likely have benefits, there is still some risk involved, cautioned Prabha Ranganathan, MD, professor of medicine at Washington University in St. Louis.
“Although most methotrexate toxicity occurs within the first 6 months of starting treatment, rare idiosyncratic toxicity can occur that does not correlate with the dose, duration, or method of how methotrexate is administered,” she wrote in an accompanying editorial. “Most rheumatologists can identify a handful of patients who receive methotrexate in their practice who develop sudden leukopenia or thrombocytopenia or transaminitis that is severe enough to warrant drug discontinuation.” While tools like this prediction model can be useful, clinicians need to consider each patient individually and use shared decision-making when monitoring for MTX toxicity, she advised.
“As in most of areas of medicine, the one-size-fits-all approach does not work for methotrexate users,” she noted.
This study was funded by the U.K. National Institute for Health and Care Research and Health Technology Assessment. Dr. Abhishek has received institutional research grants from AstraZeneca and Oxford Immunotech and personal fees from UpToDate, Springer, Cadila Pharmaceuticals, NGM Bio, Limbic, and Inflazome. Dr. Furst and Dr. Ranganathan report no relevant financial relationships.
A version of this article first appeared on Medscape.com.