The frequency of sacroiliitis on MRI in subjects over 55 years of age.

The frequency of sacroiliitis on SIJs-MRI in subjects > 55 years is similar to its frequency in younger subjects and is associated with the same type and magnitude of active and structural MRI lesions. Clinical parameters such as IBP and additional SpA features are similarly prevalent in older and younger subjects suggesting they suffer from the same disease and differing only in age of presentation.