Demographic, clinical and US data of patients with gout and CPPD disease with US evidence of DC sign
| Patients with gout (n=47) | Patients with CPPD disease (n=9) | |
| Age (years, mean (SD)) | 59.9 (14.8) | 71.8 (7.4) |
| Sex, female (n (%)) | 3 (6.4%) | 5 (55.6%) |
| Body mass index (kg/m2, mean (SD)) | 25.9 (4.8) | 25.0 (2.3) |
| Familiar history of gout (n (%)) | 11 (23.4%) | NA |
| Disease duration since diagnosis (years, mean (SD)) | 6.3 (7.1) | 6.5 (3.9) |
| Subcutaneous tophi (n (%)) | 5 (10.6%) | 0 |
| Urate-lowering therapy (n (%)) | 47 (100%) | 0 |
| C reactive protein level (mg/dL, mean (SD)) | 0.6 (0.4) | 0.5 (0.7) |
| Serum urate, latest measurement (μmol/l, mean (SD)) | 342.9 (94.9) | NA |
| Latest measurement of serum urate >360 µmol/L(n (%)) | 30 (37.0%) | NA |
| Crystal-proven diagnosis | 30 (63.8%) | 9 (100%) |
| EULAR clinical presentation | ||
| - Osteoarthritis with CPPD (n, (%)) | NA | 5 (55.6%) |
| - Acute CPP crystal arthritis(n, (%)) | NA | 2 (22.2%) |
| - Chronic inflammatory CPP crystal arthritis(n, (%)) | NA | 2 (22.2%) |
| CPPD disease aetiology | ||
| - Idiopathic (n, %) | NA | 7 (77.8%) |
| - Associated with predisposing conditions (n, %) | NA | 2 (22.2%) |
| US evidence of the OMERACT DC sign (no of joints) | 57 | 13 |
| - DC sign with CPP deposits within the HC | 0 | 4 (30.8%) |
| - DC sign without CPP deposits within the HC in the same joint | 57 (100%) | 9 (69.2%) |
| - DC sign without any CPP deposits in the same joint | 55 (96.5%) | 3 (23.1%) |
| Dynamic behaviour of the OMERACT DC sign (no of joints) | ||
| - Moving together with the HC | 57 (100%) | 3 (23.1%) |
| - Moving in the opposite direction to the HC | 0 | 10 (76.9%) |
| Distribution of joints with US evidence of the OMERACT DC sign | ||
| - Knee | 20 (35.1%) | 6 (46.2%) |
| - Ankle | 14 (24.6%) | 1 (7.7%) |
| - MTP1j | 17 (29.8%) | NA |
| - Elbow | NA | 3 (23.1%) |
| - Wrist | 1 (1.8%) | 0 |
| - MCP2j | 5 (8.8%) | 3 (23.1%) |
CPPD, calcium pyrophosphate deposition; DC, double contour; HC, hyaline cartilage; MCP2j, metacarpophalangeal joint of the second digit; MTP1j, metatarsophalangeal joint of the first digit; NA, not assessed; OMERACT, Outcome Measure in Rheumatology; US, ultrasound.