THURSDAY, June 2 (HealthDay News) -- Patients with ankylosing spondylitis, a form of arthritis targeting the spine, showed a slowing of disease progression when they took a non-steroidal anti-inflammatory pain reliever (NSAID) regularly rather than whenever they happened to feel pain, French researchers report.

NSAIDs include common over-the-counter painkillers such as aspirin, ibuprofen and naproxen (Aleve), as well as the prescription cox-2 inhibitor, Celebrex.

The two-year study began with 215 patients with ankylosing spondylitis, divided into two groups. One group was prescribed twice-daily NSAID treatment while the other group was told to only take an NSAID when they experienced pronounced pain or stiffness. All patients started out using a 100-milligram dose of Celebrex, but were allowed to increase that dose or switch to another NSAID if they so desired.

The patients were assessed at regular intervals throughout the study. X-rays of their spines were taken at the start of the study, and then again at the study's end, two years later.

Overall, the researchers observed no statistical differences between the two groups in terms of symptoms such as spinal pain, night pain, morning stiffness, fatigue and restricted mobility. There were also no significant differences in terms of gastrointestinal, respiratory, cardiovascular or other health problems.

However, the researchers did find significant differences in X-ray evidence of disease progression. Twice as many patients who took NSAIDs only when needed scored moderate-to-high levels of spinal cord damage at the two-year mark, compared to patients who took an NSAID on a continuous basis.

The researchers said the findings may prove important for both the treatment of ankylosing spondylitis and the use of NSAIDs.

"On the strength of the data, inflammation and progression of joint damage may be two separate processes in ankylosing spondylitis, which may be different from the situation in rheumatoid arthritis. And NSAIDS, generally considered symptom modifiers, may have unexplored disease-controlling properties," the study authors wrote.

The findings appear in the June issue of Arthritis & Rheumatism.

More information

The American College of Rheumatology has more about ankylosing spondylitis.