Smoking has a dose dependent impact on disease activity in axial spondyloarthritis and accelerates the progression of patients onto biologic medicines, New Zealand research has found.
The novel finding comes from the Spondyloarthritis Genetics and the Environment study – a multicentre, longitudinal study that has followed 368 participants for about five years.
Rheumatologist Associate Professor Simon Stebbings, from the University of Otago, said smokers had consistently higher disease activity than non-smokers for the first two years.
“But in the third year the level of inflammation fell in smokers quite significantly. It’s because about 80% of smokers had gone onto a biologic therapy compared to about 40% of non-smokers,” he said.
Associate Professor Stebbings said encouraging smokers to quit may prevent progression to biologics, which was not only important for individuals but also from a health economics perspective.
The study found a correlation between smoking history as determined by pack years and C-reactive protein as a marker of inflammation. The study also used the Ankylosing Spondylitis Disease Activity Score (ASDAS and the Bath Ankylosing Spondylitis Functional Index (BASFI) as outcome measures.
“From our research, it appears smoking makes disease activity worse, physical function is worse and it effects the efficacy of drugs to control the disease.”
“If they can’t stop smoking, then we could anticipate some benefit from cutting down,” he added.
Associate Professor Stebbings said the findings were consistent with evidence in rheumatoid arthritis where smokers were more likely to be diagnosed with the disease, have worse disease and respond less effectively to medications.
He said a recent study in patients with rheumatoid arthritis showed no increase in quit rates from an arthritis-specific intervention for smoking cessation compared to usual supports such as referral to Quitline.
“We could extrapolate to spondyloarthritis and say the resources are already there. Patients don’t need anything else to quit.”
He said the smoking rate in their cohort was slightly lower than the general New Zealand population (15 v 17%) possibly reflecting a difference in ethnicity rather than patients seeing a doctor or being advised to quit.