Background/Purpose The gold standard for the diagnosis of acute MSU induced arthritis is crystal identification by microscopy after joint aspiration. Alternative diagnostic tools that have been proposed include joint ultrasonography (US) and a clinical score for gout (Nijmegen Score – NS) that has been validated in a primary care setting. Most US studies have been performed in patients with known gouty arthritis. The primary objective was to compare the performance of US as diagnostic tool with the NS in the diagnosis of suspected acute gouty arthritis, using synovial fluid analysis as a gold standard. The secondary objective was to evaluate whether the performance of NS could be enhanced by combining with US data

Methods All consecutive patients who presented with acute arthritis suspected to be of microcrystalline origin between October 2012 and May 2014 were prospectively included. The duration of arthritis symptoms was <10 days. All patients underwent a clinical and an US evaluation of the symptomatic joint as well as of the knees, the ankles and the first MTP joints (multiple joints). Joint aspiration of the symptomatic joint was performed within 24 hours.. US was performed by2 rheumatologists skilled in US who were blinded to the clinical data. The NS was calculated “a posteriori” by a clinician not implicated in the primary evaluation of patients. We applied a cut-off value of  > 8 as proposed by the authors of the NS for the diagnosis of gout (1). US diagnosis of gout was evaluated firstly on typical US signs (“Double contour” and or tophi) in the symptomatic joint and secondly on signs of gout in all the other joints

Results

117 patients were included. Joint fluid was obtained in 112 patients. MSU crystals were detected in 61 patients (54%), CCP crystals were found in 29 (26%) and no crystals were found in 22 (20%). The mean (± SD) NS scores differed significantly between gout 8.8 (±2.4) and non-gout groups 4.6 (±2.8) (p < 0.05). In CPP patients, the mean NS score was 4.3(±2.3). US signs of gout were found in symptomatic joints of 40  patients, and by multiple joints US, signs of gout were found in 68 patients.

The table describes the sensitivity, the specificity, and the positive predictive value (PPV)of the NS, US and the combination of both US and NS in the diagnosis of gouty arthritis.  NS score alone or US of the affected joint alone had moderate sensitivity but reasonable specificity for diagnosis of gout in our cohort. The best diagnostic performance was obtained with either US in multiple joints or the NS  + US in the symptomatic joints

	Clinical score (>8)	USSymptomatic joint	US Multiple joints	Clinical score +US symptomatic joint		Clinical score+US multiple joints
Sensitivity : %	62	60	84		80	90
Specificity %	86	92	78		82	74
PPV%	84	90	84		84	81

Conclusion The NS score alone or US alone of the affected joints were moderately sensitive in the diagnosis of acute gout, but had good specificity. Combining the NS score with US evaluation of the symptomatic joint enhanced the diagnostic performance but does not replace the need for crystal-identification by microscopy in the diagnosis of acute gouty arthritis

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/can-we-diagnose-acute-gout-without-joint-aspiration-results-of-a-prospective-study-of-112-patients-presenting-with-acute-arthritis/