Objective: Imaging evidence of active sacroiliitis is important for diagnosis, classification, and monitoring of axial spondyloarthritis (axSpA). However, is no consistent guidance whether patients should temporarily stop Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) prior to MRI.
Aim: to determine whether NSAIDs lead to an underestimation of active sacroiliitis, as observed using MRI.
Methods: Adults with axSpA were recruited from rheumatology clinics and undertook NSAID washout for 1-2wks prior to a sacroiliac joint MRI. Images were read by two independent readers, adjudicated by a third if required. Those who scored positive for active sacroiliitis, as per internationally recognised criteria, underwent a second scan 6wks after recommencing daily NSAIDs. We determined the proportion of participants who scanned negative on NSAIDs, having previously scanned positive when NSAID-free. Images were also scored using semi-quantitative methods comprising lesion size and intensity, and a sub-set of participants underwent quantitative MRI (qMRI) to provide an objective evaluation of any inflammatory changes.
Results: From 34 centres across the UK 311 participants (median age 42yrs; 62% male) were recruited; 286 (92%) completed the NSAID washout and underwent the first MRI. From 146 participants with active sacroiliitis, follow-up scans (on NSAIDs) were obtained from 124 (85%), at which point 25 scanned negative (20.2%; 95%CI: 13.5 to 28.3%). Semi-quantitative and qMRI methods supported these findings.
Conclusion: One-fifth of patients show full resolution of active sacroiliitis lesions when NSAIDs were present. In clinical practice, if patients with axSpA are willing to attempt a 1-2 week NSAID washout prior to MRI, this should be considered.
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