THU0420 ULTRASOUND SHOWS GREAT ACCURACY FOR THE DIAGNOSIS OF CRYSTAL ARTHRITIS IN PATIENTS WITH RECENT-ONSET SYNOVITIS
Authors: E. Cipolletta, A. DI Matteo, E. Filippucci, W. Grassi
Journal: Annals of the Rheumatic Diseases (2020)

Background: The value of ultrasound (US) in the diagnosis of crystal arthropathy, such as gout or calcium pyrophosphate deposition disease (CPPD), in patients with recent onset synovitis has been evaluated only by a few studies. Objectives: To investigate, in patients with acute arthritis, the accuracy of US for the diagnosis of crystal arthropathy. Methods: Consecutive patients with recent onset (&lt;6 weeks) acute arthritis were enrolled. The US examinations were performed a rheumatologist blinded to clinical data. Calcium pyrophosphate and monosodium urate crystal deposits were identified in the joint affected by synovitis (target joint), as well as in the classic sites for gout and CPPD (set of joint) (Table 1), according to the OMERACT definitions. Table 1. Anatomical targets of ultrasound examination Gout CPPD Both Wrist Radiocarpal j Intercarpal j Triangular FC complex Scapho-lunate ligament / Hand DC in the II MCPj HC Deposits within the II MCPj HC II MCPj Knee Popliteal groove DC in the femoral condyle’s HC Meniscal FC Deposits within the femoral condyles’ HC Supra-patellar recesses Hip DC in the femoral head’s HC Deposits within the femoral head’s HC Acetabular FC Hip j Foot DC in the I MTPj HC Deposits within I MTPj HC I MTPj Legend . DC : double contour, FC : fibrocartilage, HC : hyaline cartilage, MCPj : metacarpophalangeal joint, MTPj : metatarsophalangeal joint, j : joint. Table 2. Diagnostic accuracy of US and SFA Sensitivity Specificity Positive LHR Negative LHR US (target joint ) Crystal arthritis 0.84 (0.7-0.93) 0.91 (0.8-0.97) 9.5 (4.1-22) 0.2 (0.1-0.3) CPPD 0.91 (0.71-0.99) 0.91 (0.80-0.97) 10.2 (4.4-23.8) 0.1 (0-0.4) Gout 0.83 (0.61-0.97) 0.91 (0.80-0.97) 9.1 (3.9-21.4) 0.2 (0.1-0.5) US (set of joints ) Crystal arthritis 0.96 (0.85-0.99) 0.87 (0.76-0.95) 7.6 (3.8-15.3) 0.1 (0-0.2) CPPD 1 (0.85-1) 0.88 (0.76-0.95) 8 (4-16) 0 (0-0.2) Gout 0.91 (0.72-0.99) 0.88 (0.76-0.95) 7.3 (3.6-14.8) 0.1 (0-0.4) SFA Crystal arthritis 0.9 (0.77-0.97) 1 (0.94-1) / 0.1 (0-0.2) CPPD 0.90 (0.7-0.99) 1.0 (0.94-1) / 0.1 (0-0.3) Gout 0.91 (0.71-0.99) 1 (0.94-1) / 0.1 (0-0.3) Legend . LHR : likelihood ratio SFA was performed in 67 knees (64.4%), 10 wrists (9.6%), 10 ankles (9.6%), 5 I MTP joints (4.8%), 5 hips (4.8%), 4 elbows (3.8%), 4 shoulders (3.8%). The total agreement between US and SFA was excellent (93.8% in CPPD and 90.2% in gout). SFA positive/US negative results occurred in 1 patient with CPPD (1.2%) and in 4 patients with gout (4.9%). On the contrary, US positive/SFA negative results occurred in 4 patients with CPPD (4.9%) and in 4 patients with gout (4.9%). The diagnostic accuracy of US and synovial fluid analysis (SFA) was evaluated taking the classification criteria for gout and CPPD as gold standard (1,2). Moreover, the US and SFA results were compared in the joints in which the SFA was performed. Results: One-hundred and four patients were enrolled: 22 CPPD patients, 23 with gout and 59 disease controls. Table 2 reports the diagnostic accuracy of US and SFA, using the classification criteria as gold standard. Figure 1 provides a pictorial evidence of the US appearance of crystal deposits. A: anterior suprapatellar transverse scan of the femoral condylar HC. HC calcifications (arrows) B: anterior longitudinal scan of the hip. FC calcification (asterisk) C: anterior longitudinal scan of the ankle. DC sign (void arrow) . D: dorsal longitudinal scan of distal interphalangeal joint. DC sign (void arrow). Conclusion: US is useful for the diagnosis of gout and CPPD in patients with acute synovitis. Extending the US evaluation to the joints which are most commonly involved in gout and in CPPD, other than those affected by synovitis, increases the sensitivity of US. References: [1]Neogi T, et al. 2015 Gout classification criteria: an ACR/EULAR collaborative initiative. Ann Rheum Dis 2015 [2]McCarty D. CPPD Disease: Nomenclature and Diagnostic Criteria. Ann Intern Med 1977 Disclosure of Interests: : Edoardo Cipolletta: None declared, Andrea Di Matteo Grant/research support from: the publication was conducted while Dr. Di Matteo was an ARTICULUM fellow, Emilio Filippucci Speakers bureau: Dr. Filippucci reports personal fees from AbbVie, personal fees from Bristol-Myers Squibb, personal fees from Celgene, personal fees from Roche, personal fees from Union Chimique Belge Pharma, personal fees from Pfizer, outside the submitted work., Walter Grassi Speakers bureau: Prof. Grassi reports personal fees from AbbVie, personal fees from Celgene, personal fees from Grünenthal, personal fees from Pfizer, personal fees from Union Chimique Belge Pharma, outside the submitted work.