OA14 Non-steroidal anti-inflammatory drugs reduce sacroiliac joint inflammation in axial spondyloarthritis
Authors: Jones Gareth T , Bennett Alex N , Sengupta Raj , Machado Pedro M , Marzo-Ortega Helena , Aucott Lorna , Macfarlane Gary J 
Published: April 2023

Abstract

Background/Aims
MRI evidence of active sacroiliitis (sacroiliac joint bone marrow oedema (BMO)) is commonly used to assist diagnosis and classification of axial spondyloarthritis (axSpA). Non-steroidal anti-inflammatory drugs (NSAIDs) are used as first-line therapy, and for persistent clinical symptoms continuous treatment is recommended. Prescribed in primary care, and widely available over-the-counter, many patients are already taking NSAIDs when first presenting to rheumatology. We hypothesised that among patients with axSpA, NSAID use would lead to an underestimation of sacroiliac joint BMO.

Methods
Adults with axSpA were recruited from NHS rheumatology clinics and asked to discontinue their NSAIDs for 1-2wks before undergoing a sacroiliac joint MRI (Scan 1) using a standardised protocol. All participants then re-started their NSAIDs. Those who scanned positive for BMO lesions, as determined using internationally recognised (ASAS) definitions, underwent a second scan 6wks after restarting NSAIDs. Scans were read independently by 2 readers (adjudicated by a 3rd, if required), blinded to participants’ clinical characteristics and timepoint. We determined the proportion of participants who scanned negative at Scan 2 (on NSAIDs) who had previously scanned positive at Scan 1 (off NSAIDs).

Results
311 participants were recruited from 34 centres. Table 1 shows participants’ baseline characteristics. Almost all participants (296; 95%) completed the NSAID washout and underwent Scan 1. However, 135 (50%) reported an increase in spinal pain (median increase: 2 points on a 0-10 numerical rating scale; inter-quartile range: 1-3), and 166 (61%) reported worsening of disease activity (median increase in BASDAI: 0.9; 0.5-1.6). At Scan 1, 149 (50%) were positive for BMO lesions. 131 (88%) participants underwent the six-week follow-up scan, of whom 31 scanned negative (24%; 95%CI: 17-32%).

Conclusion
These findings suggest that NSAIDs influence sacroiliac BMO and, where sacroiliitis is present, around one-in-four show resolution of lesions when NSAIDs are present - with important implications for axSpA diagnosis and classification. If patients with axSpA (or suspected axSpA) are willing to attempt NSAID washout prior to MRI, this should be considered. There may be concerns about increases in disease activity or spinal pain, but we also provide evidence that almost all patients who attempt washout can successfully achieve it.
Disclosure
G.T. Jones: None. A.N. Bennett: Consultancies; Abbvie, Eli Lilly, MSD, Novartis, Pfizer, UCB. Honoraria; AbbVie, Biogen, Novartis, Pfizer, UCB. Grants/research support; Pfizer. R. Sengupta: Consultancies; AbbVie, Biogen, Eli Lilly, Novartis, Pfizer, UCB. Member of speakers’ bureau; AbbVie, Biogen, Celgene, Eli Lilly, Novartis, Pfizer, UCB. Grants/research support; AbbVie, Celgene, Novartis, UCB. P.M. Machado: Honoraria; AbbVie, BMS, Celgene, Eli Lilly, Galapagos, Janssen, MSD, Novartis, Orphazyme, Pfizer, Roche, UCB. H. Marzo-Ortega: Consultancies; Eli Lilly, Janssen, MoonLake, Novartis, Pfizer, UCB. Member of speakers’ bureau; AbbVie, Biogen, Celgene, Eli Lilly, Janssen, Novartis, Pfizer, Takeda, UCB. Grants/research support; Janssen, Novartis, UCB. L. Aucott: None. G.J. Macfarlane: None.