Table 3.

Sensitivity, specificity, PPV, and NPV of different US and dermoscopic features for early PsA versus early seronegative and seropositive RA.

VariablesSensitivity (95% CI)Specificity (95% CI)PPV (95% CI)NPV (95% CI)
US
  PTI pattern at MCP joint36.0% (18.0–57.5)95.2% (83.4–99.4)81.8% (51.4–95.0)71.4% (64.9–77.2)
  CSE pattern at PIP joint20.0% (6.8–40.7)100% (91.6–100)100% (47.8–100)67.7% (63.3–71.8)
  STE-FT of the digit40.0% (21.1–61.3)90.5% (77.4–97.3)71.4% (46.7–87.7)71.7% (64.5–78.0)
  At least 1 of the abovementioned US features68.0% (46.5–85.0)88.1% (74.4–96.0)77.3% (58.9–89.0)82.2% (72.1–89.2)
Dermoscopy
  Dotted vessels of proximal nailfold96.0% (79.7–99.9)83.3% (68.6–93.0)77.4% (63.4–87.1)97.2% (83.6–99.6)
US + dermoscopy
  At least 1 US feature + dotted vessels of
  proximal nailfold on dermoscopy
68.0% (46.5–85.0)90.5% (77.4–97.3)81.0% (61.7–91.8)82.6% (72.7–89.5)
  • PPV: positive predictive value; NPV: negative predictive value; US: ultrasonography; PsA: psoriatic arthritis; RA: rheumatoid arthritis; PTI: peritendon inflammation of the extensor digitorum tendon; MCP: metacarpophalangeal; CSE: central slip enthesitis; PIP: proximal interphalangeal; STE-FT: soft tissue edema around flexor tendon.