Researchers from University Hospital Zurich looked at how 700 people with this type of arthritis responded to treatment with a class of drugs called tumor necrosis factor inhibitors. About two-thirds of the patients were smokers.
After one to two years of treatment, the drugs were significantly less effective in smokers. The difference was particularly apparent among patients who had higher levels of an inflammatory marker called C-reactive protein at the start of the study.
Former smokers did not experience reduced effectiveness from the drugs, according to the study. The research only saw an association between smoking and the drugs’ benefits, not a cause-and-effect relationship.
The results were published online in the journal Annals of the Rheumatic Diseases.
It’s not clear how smoking might impair patients’ response to these biological drugs, the researchers said. Smoking may trigger a rise in inflammation, increase pain by interfering with nerves, or starve tissues of oxygen, they suggested.
According to the researchers, previous studies have shown that smoking increases the risk of rheumatoid arthritis and blunts the effectiveness of several arthritis drugs.
They added that this is one of the first studies to examine how smoking affects treatment in people with inflammatory arthritis in the lower back.