Naushad Hirani, BSc, MD*

The seronegative arthritides, also commonly referred to as the spondylo-arthropathies because of their predilection for involving the spine, are inflammatory diseases that can be distinguished from the more common rheumatoid arthritis and osteoarthritis based on several general characteristics. In addition to being, by definition (with rare exceptions), rheumatoid factor negative (as opposed to rheumatoid arthritis), they also have distinct patterns of articular and extra-articular involvement, and most exhibit an association with the HLA-B27 gene.

The main conditions encompassed by this classification include Psoriatic arthritis (PSA), Reactive arthritis or Reiter's syndrome, and Inflammatory bowel disease-associated arthritis, although Ankylosing spondylitis⁼ (AS) is the prototypical seronegative disease. The key features of each of the seronegative arthritides are summarized in Table 1. From a geriatric standpoint, most of these conditions are not diagnostic challenges, as they are generally diseases that present in young or middle-aged people. However, an understanding of the group of diseases is helpful for the management of patients in the chronic state, and particularly in the case of distinguishing PSA from rheumatoid arthritis. Many of the features of the seronegative arthritides can be illustrated by first considering AS.