Etanercept seems to be the TNF inhibitor of choice over time for people with rheumatoid arthritis (RA). In a large Swedish study lasting five years people were less likely to switch from etanercept than from infliximab or adalimumab. This doesn’t mean that etanercept is more effective, it just means that some patients find it works better for them than the other options.
Tumour necrosis factor (TNF) inhibitors, also known as biologics, are still fairly recent additions to the treatment options for RA. In the UK doctors generally only offer TNF inhibitors to people who don’t do well on the more established disease-modifying anti-rheumatic drugs (DMARDs) such as methotrexate. However, their use is becoming more common and researchers are finding out more about them.
WHAT DID THE RESEARCHERS HOPE TO FIND?
The researchers were interested in studying what they call ‘drug survival’: how long someone uses a particular drug treatment before they decide it’s either not doing them much good or it’s causing unbearable side effects. The researchers in this study wanted to find out how three TNF inhibitors – etanercept, infliximab, and adalimumab – compared with each other in terms of how many people stuck with them and how many switched to another treatment.
WHO WAS STUDIED?
The study covered more than 9,000 people in Sweden with RA. The researchers looked at the data for people who started treatment with TNF inhibitors in two time periods, the first between 2003 and 2005, and the second between 2006 and 2009. This gave the researchers the chance to see whether people’s acceptance of the various drugs changed as the drugs became more established as treatment options.
HOW WAS THE STUDY CONDUCTED?
The researchers used Swedish medical records (specifically a database called the Swedish Biologics Register) to look at people using TNF inhibitors for the first time. Over a five-year period (for each of the two groups) they then looked at how many people stopped using them and why.
WHAT DOES THE NEW STUDY SAY?
About half the people in the study stopped treatment with their first TNF inhibitor at some point during the five-year study period. People were more likely to stop using their treatment because they felt it didn’t work well enough than because it caused side effects. ▸ The drug with the highest rate of people stopping treatment was infliximab.
▸ The drug with the lowest rate of people stopping treatment was etanercept.
▸ People were more likely to stop taking adalimumab than etanercept, but only in the first year of treatment. The researchers aren’t sure why this was.
▸ More people in the later study group (those who started treatment between 2006 and 2009) stopped treatment with TNF inhibitors, even though people in this group judged that the drugs worked better and caused fewer side effects.
HOW RELIABLE ARE THE FINDINGS?
This study has a lot of strong points: it used reliable data, included a lot of people, had a long follow-up period and included the majority of biological treatments available for RA at the time. It was also what’s called a ‘real world’ study using data from medical records and databases. This means that the people weren’t enrolled in a drug trial so their decision-making was less prone to bias and arguably more natural than if they’d known they were going to be part of a study.
WHAT DOES THIS MEAN FOR ME?
Perhaps this study’s most interesting finding is that people in the later study group were more likely to decide to change treatments than those in the earlier group, even though they rated the treatments higher than the earlier group had. The researchers say that this reflects higher expectations of treatment as time has gone on, and that people know that the number of available treatments for RA is increasing. The other thing to say is that, just because people in this study were most likely to stick with etanercept and least likely to keep using infliximab, that doesn’t mean that etanercept is necessarily a ‘better’ treatment. For example, it’s possible that some people didn’t like infliximab because it is given by an infusion or ‘drip’, which takes longer than treatment with the other drugs, which are given by injection. This study’s findings are interesting, but the most important thing is to find the treatment that works for you. And, finally, it might seem gloomy that half the people studied felt they needed to change from the first TNF inhibitor they tried. But let us put it another way. Half the people were happy with their first TNF inhibitor, and were still happy with it five years later. With a condition like RA where many people have to try several treatments before they find what works best, that’s arguably not a bad average.
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Date summary prepared: February 2015
Summary based on research article published on: 27 November 2013
From: Neovius M, Arkema EV, Olsson H, et al. Drug survival on TNF inhibitors in patients with rheumatoid arthritis comparison of adalimumab, etanercept and infliximab. Ann Rheum Dis 2015;74:354–60. doi:10.1136/annrheumdis-2014-201428
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