Table 2

Construct (Cronbach α test) and external validity of the different clinical and ultrasonographic scoring systems evaluated in 76 patients with active rheumatoid arthritis

Scoring systemConstruct validity (Cronbach α test)External validity (vs CRP: coefficient of correlation)
Joint count*
20 Clinical0.760.28
20 US B mode0.760.28
20 US power Doppler0.810.37
28 Clinical0.780.35
28 US B mode0.870.35
28 US power Doppler0.860.43
38 Clinical0.780.35
38 US B mode0.860.30
38 US power Doppler0.850.39
Joint score*
20 Clinical0.860.29
20 US B mode0.830.28
20 US power Doppler0.820.34
28 Clinical0.850.31
28 US B mode0.890.39
28 US power Doppler0.840.38
38 Clinical0.880.31
38 US B mode0.880.34
38 US power Doppler0.850.37
  • * See Patients and methods section for the definition of count versus score and for the description of the evaluated joints.

  • CRP, C reactive protein; US, ultrasound.