Session Information
Date: Tuesday, November 10, 2015
Title: Metabolic and Crystal Arthropathies II: Mechanisms and Associations
Session Type: ACR Concurrent Abstract Session
Session Time: 4:30PM-6:00PM
Background/Purpose:
Musculoskeletal ultrasound (US) is a non-invasive option for diagnosing gout.
However, little is known about the test characteristics of US for the diagnosis
of gout in clinical practice. The objective of this study was to determine the diagnostic
performance of ultrasound for the diagnosis of gout using presence of monosodium
urate (MSU) crystals as the gold standard.
Methods: A sub
study was performed within the Study for Updated Gout Classification Criteria (SUGAR),
a large, multi-center observational cross-sectional study in consecutive subjects
with at least one swollen joint who conceivably may have gout. Cases were subjects
with MSU crystal confirmation and controls had an arthrocentesis
negative for MSU crystals. Rheumatologists or radiologists, blinded to the
results of the MSU crystal analysis, performed US on an involved joint. US
findings of interest were: double contour sign (DCS), tophus, and snowstorm appearance. Sensitivity and specificity were
calculated for these features. Multivariable logistic regression models were
used to examine factors associated with true positive US results.
Results: Among
982 subjects enrolled in SUGAR, ultrasound was performed in 824 subjects (416
cases and 408 controls).
Sensitivity and specificity for DCS, tophi, snowstorm, and any US
feature for all subjects, those with early (<2 years since symptom onset) versus
late disease (³2 years since symptom onset), and the presence or absence of suspected
clinical tophi on examination are shown in the Table. Among subjects with gout,
249 (60%) subjects had a DCS, 189 (46%) had US evidence of tophus, and 125
(30%) had a “snowstorm” appearance on ultrasound. Associations with a true
positive DCS result included highest ever serum uric acid (SUA; OR 1.31; 95%CI:
1.13-1.53), tender joint proximal to the ankle (2.02; 1.34-3.04) and any xray feature of gout (3.04; 1.95-4.75). Associations with a true positive US
tophus included suspected clinical tophus on exam (7.47; 4.72-11.84), current
SUA (1.22; 1.05-1.41), and asymmetrical swelling on joint xray
(6.14; 3.93-9.60). Finally,
associations with a true positive “snowstorm” included suspected clinical
tophus on exam (2.29; 1.40-3.76), cystic changes on X-ray (1.70; 1.06-2.72),
and the number of episodes (compared to 1 as the reference, 2-5 episodes OR
0.20; 0.06-0.51 and >5 episodes OR 0.34; 0.15-0.76).
Conclusion: In
this study, US features of gout have high specificity (but more limited sensitivity) for gout. This was also true in subjects with
early disease and in those without suspected clinical tophi on clinical
examination. However, sensitivity of
DCS and US tophus was better for subjects with long
standing disease compared to those with early disease. The presence of other
features of gout (e.g. suspected clinical tophus, elevated SUA or xray features) increased the likelihood of achieving a true
positive result.
|
Table. Sensitivity and Specificity of US Features of Gout
|
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|
Cases
|
Controls
|
Sensitivity
|
Specificity
|
|
|
Ultrasound: DCS |
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|
All subjects |
249/414 (60%) |
35/408 (9%) |
60.1% |
91.4% |
|
Early disease (<2 yrs) |
55/108 (51%) |
15/195 (8%) |
50.9% |
92.3% |
|
Late disease (³2 yrs) |
192/303 (63%) |
18/209 (9%) |
63.4% |
91.4% |
|
No suspected clinical tophus* |
141/264 (53%) |
27/389 (7%) |
53.4% |
93.1% |
|
Suspected clinical tophus* |
107/149 (72%) |
8/19 (42%) |
71.8% |
57.9% |
|
Ultrasound: Tophus |
||||
|
All subjects |
189/411 (46%) |
21/408 (5%) |
46.0% |
94.9% |
|
Early disease (<2 yrs) |
36/107 (34%) |
9/195 (5%) |
33.6% |
95.4% |
|
Late disease (³2 yrs) |
152/301 (51%) |
10/209 (5%) |
50.5% |
95.2% |
|
No suspected clinical tophus* |
77/262 (29%) |
13/389 (3%) |
29.4% |
96.7% |
|
Suspected clinical tophus* |
112/148 (76%) |
8/19 (42%) |
75.7% |
57.9% |
|
Ultrasound: Snowstorm |
||||
|
All subjects |
125/412 (30%) |
37/407 (9%) |
30.3% |
90.9% |
|
Early disease (<2 yrs) |
35/108 (32%) |
15/195 (8%) |
32.4% |
92.3% |
|
Late disease (³2 yrs) |
89/301 (30%) |
20/208 (10%) |
29.7% |
90.4% |
|
No suspected clinical tophus* |
63/262 (24%) |
29/388 (7%) |
24.1% |
92.5% |
|
Suspected clinical tophus* |
62/142 (42%) |
8/19 (42%) |
41.6% |
57.9% |
|
Ultrasound: Any feature |
||||
|
All subjects |
320/416 (77%) |
64/408 (16%) |
76.9% |
84.3% |
|
Early disease (<2 yrs) |
78/109 (72%) |
31/195 (16%) |
71.6% |
84.1% |
|
Late disease (³2 yrs) |
239/304 (79%) |
31/209 (15%) |
78.6% |
85.2% |
|
No suspected clinical tophus* |
182/265 (69%) |
55/389 (14%) |
68.7% |
85.9% |
|
Suspected clinical tophus* |
137/150 (91%) |
9/19 (48%) |
91.3% |
52.6% |
|
The number of available test results for each imaging feature may differ as some features were not reported for all subjects. *Suspected clinical tophus refers to clinically apparent tophus on physical examination |
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To cite this abstract in AMA style:
Ogdie-Beatty A, Taylor WJ, Neogi T, Fransen J, Jansen T, Schumacher HR Jr., Dalbeth N. Diagnostic Value of Ultrasound for the Diagnosis of Gout in a Prospective Cross-Sectional Study [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/diagnostic-value-of-ultrasound-for-the-diagnosis-of-gout-in-a-prospective-cross-sectional-study/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/diagnostic-value-of-ultrasound-for-the-diagnosis-of-gout-in-a-prospective-cross-sectional-study/