Smoking may interfere with how biologic medicines reduce inflammation and joint damage in people with axial spondyloarthritis.
Spondyloarthritis is an umbrella term for several conditions that share many of the same features and symptoms, including ankylosing spondylitis, psoriatic arthritis and reactive arthritis. Patients can also be classified as having axial or non-axial (peripheral) disease, according to which joints in their body are affected. Axial disease affects the sacroiliac joint (in the back part of the pelvis and spine) causing back pain and stiffness. TNF inhibitors belong to a group of medicines called biologic disease modifying antirheumatic drugs, or bDMARDs, (sometimes also called biologics), and include adalimumab, etanercept, infliximab, golimumab and certolizumab-pegol. These drugs work by targeting specific molecules that cause inflammation. By doing so they reduce inflammation in the joints, and decrease pain and disease worsening.
WHAT DID THE AUTHORS HOPE TO FIND?
The authors wanted to see whether smoking has an effect on how well people with axial spondyloarthritis respond to treatment with TNF inhibitors.
WHO WAS STUDIED?
The study included 490 people with axial spondyloarthritis in clinics across Switzerland, where patients are seen by their rheumatologist at least once a year. All patients were receiving a TNF inhibitor and had provided their current smoking status and history.
HOW WAS THE STUDY CONDUCTED?
This was a longitudinal study undertaken within a larger observational registry. There was no intervention or drug under investigation. The treating rheumatologists simply observed and recorded information about the people in a single study database. A study of this type is used to compare different groups of people at a single point in time, without changing any variables. Over a 9-year period, information was collected on disease activity and the response to treatment with TNF inhibitors. The results were compared between people who were current smokers, past smokers and those who had never smoked.
WHAT WERE THE MAIN FINDINGS OF THE STUDY?
The authors found that smokers have more functional impairment than non-smokers. This means that their joints are more badly affected by their disease, and they are more likely to have disability. Current smokers also showed a worse response to treatment with TNF inhibitors than did non-smokers. People who had quit smoking or reported themselves as past smokers had similar results to those who had never smoked, with better functional ability and better response to treatment than current smokers.
ARE THESE FINDINGS NEW?
It is already known that smoking can have an effect on disease severity in people with rheumatoid arthritis, another chronic inflammatory joint disease. This is the first time that the effect of smoking has been looked at in people with axial spondyloarthritis, and is the first time that the effect of smoking on the efficacy of TNF inhibitors has been investigated.
HOW RELIABLE ARE THE FINDINGS?
There are some limitations in the study. Information was not collected on how many cigarettes people smoked, or how long they had been smoking for. There was also no information on how recently ex-smokers had quit. Also, some people dropped out of the study and their data was lost. However, the authors are confident that the findings are reliable.
WHAT DO THE AUTHORS PLAN ON DOING WITH THIS INFORMATION?
This information will be important for doctors and will help to intensify efforts to help patients to stop smoking. More studies may be undertaken to confirm the effect of smoking on TNF inhibitors.
WHAT DOES THIS MEAN FOR ME?
If you have axial spondyloarthritis, or another inflammatory condition, smoking could make your disease worse, causing more pain and disability. It can also reduce how well your medicine works. If you currently smoke, you should talk to your doctor about ways to quit.
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Date prepared: March 2016
Summary based on research article published on: 9 February 2015
From: Ciurea, A. et al. Impaired response to treatment with tumour necrosis factor α inhibitors in smokers with axial spondyloarthritis. Ann Rheum Dis 2016;75:532–39. doi:10.1136/annrheumdis-2013-205133
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