Smoking can increase x-ray damage in people with ankylosing spondylitis by as much as five times

Ankylosing spondylitis is a type of inflammatory arthritis characterized by joint stiffness, pain and extra bone growth that can result in partial or complete fusion of the spine. The disease typically affects young men and may lead to work disability and spinal deformity.

"The OASIS study follows a large number of patients over 12 years according a fixed protocol with assessments of many outcomes, including radiographs, says Sofia Ramiro, MD who is the lead investigator in the study. "This provides a unique opportunity to assess long-term outcome."

Through OASIS, 127 people with ankylosing spondylitis were followed by Dr. Ramiro's team for 12 years. The participants -- 71 percent of which were men with an average age of 41 and an average symptom duration of 18 years -- received a physical exam and X-rays every other year. X-rays were scored by two independent reviewers and disease progression was assessed based on the modified Stoke Ankylosing Spondylitis Spine Score.

To evaluate inflammation, the AS Disease Activity Score (an instrument that combines patient's evaluation of the disease and a marker of inflammation in the blood called C-reactive protein) was used. The relationship between ASDAS and damage was investigated over the 12 years by assessing the effect of inflammation at one point in time on the progression of damage two years later. After that, the effect of factors possibly influencing this relationship was investigated.

Dr. Ramiro's team noted that smoking significantly increased the impact of inflammation on X-ray damage across all groups, but especially among men with less than 18 years of symptoms. Overall, smokers had a 5.5 times higher effect of inflammation on X-ray damage compared to non-smokers, and male smokers had a startling 13.4 times higher effect of inflammation on damage when compared to women who did not smoke.

"Our study shows that smoking, especially in male patients, means that the same level of inflammation leads to much more new bone formation in the spine. Also in patients with short symptom duration, inflammation leads to more damage as compared to later in the disease. Smoking cessation, most importantly in young male patients with SpA, may lead to less spinal damage and therefore better long-term outcome," says Dr. Ramiro.