Ankylosing spondylitis (AS) is an inflammatory spinal disease which is associated with varying degrees of spinal fusion. The parameters that seem to increase the risk for spinal fusion in AS include male sex, histocompatibility type HLA-B27, smoking, elevated C reactive protein, and presence of bony bridges between vertebral bodies (syndesmophytes) at the time of diagnosis.
The goal of therapy for AS is to decrease inflammation and stop the progression of bony fusion. A number of agents are approved by the Food and Drug Administration (FDA) for the treatment of AS including NSAIDs, tumor necrosis factor inhibitors (TNFi), interleukin-17 (Il-17) and Janus kinase (JAK) inhibitors. Although these agents are effective at decreasing inflammation, the benefit of controlling new bone growth is not clear.
NSAIDs are the first line of therapy for AS. In studies of AS patients, upwards of 90% are taking NSAIDs. They are also effective in combination with biologic therapies, particularly for spinal pain.
NSAIDs do have effects on bone metabolism. Certain enzymes, primarily cyclooxygenase 2, do have a promoting effect on bone formation. This is most notable with acute fractures, but may be also important in AS bone formation. NSAIDs are Cox-2 inhibitors. The use of NSAIDs during fracture healing may be associated with non-union. Most spine surgeons prohibit the use of NSAIDs after spine fusion operations.
The question for an AS patient is whether therapy should include NSAIDs; And if they do, should NSAIDs be used on a continuous basis? The treatment guideline from the American College of Rheumatology recommends the continuous use of NSAIDs. The benefit of this therapy may be the inhibition of bone growth, as well as pain relief. Additional studies are needed to show that bone formation is prevented by NSAIDs. Until that time comes, a daily NSAID is worthwhile from a risk-benefit perspective.
- Wang R, Bathon JM, Ward MM..Nonsteroidal anti-inflammatory drugs as potential disease-modifying medications in axial spondyloarthritis. Arthrits Rheumatol 2020;72:518-528
- Ward MM et al: 2019 update of the American College of Rheumatology/ Spondylitis Association of America/Spondyloarthritis research and treatment network recommendations for the treatment of ankylosing spondylitis and nonradiographic axial spondyloarthritis. Arthritis Rheumatol 2019:71:1599-613