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Table 3 Item fit statistics

From: Psychometric properties of the painDETECT questionnaire in rheumatoid arthritis, psoriatic arthritis and spondyloarthritis: Rasch analysis and test-retest reliability

Mean square - Z standard deviation
RA PsA SpA All diagnoses
Item Infit Outfit Infit Outfit Infit Outfit Infit Outfit
1 0.82 −2.4 0.8 −2.3 1.04 0.6 1.06 0.7 0.91 −1.1 0.95 −0.5 0.92 −1.7 0.94 −1.2
2 0.93 −0.9 0.86 −1.5 0.72 −3.8 0.67 −3.4 0.84 −2.0 0.79 −1.8 0.84 −3.5 0.80 −3.5
3 1.04 0.5 1.01 0.2 0.99 −.01 0.99 −.01 1.02 0.3 1.01 0.2 1.01 0.2 1.00 0.1
4 1.01 0.2 0.97 −0.3 1.08 1.0 1.02 0.2 1.0 0.0 0.93 −0.6 1.03 0.6 0.97 −0.4
5 1.14 1.7 1.09 1.1 1.09 1.2 1.07 0.9 1.14 1.7 1.11 1.3 1.12 2.5 1.09 1.9
6 1.14 1.7 1.21 1.9 1.24 2.9 1.26 2.4 1.08 1.0 1.12 1.1 1.14 2.9 1.19 2.9
7 0.98 −0.2 0.99 0.0 0.91 −1.2 0.84 −1.8 1.04 0.6 1.05 0.6 0.99 −0.1 1.00 0.0
  1. Critical values for mean squares were calculated based on the sample sizes for the separate diagnosis (infit MnSq = 1.12, outfit MnSq = 1.35, ZSTD < 2) and overall (infit MnSq =1.06, outfit MnSq S = 1.2, ZSTD < 2) respectively. Item1. Burning sensations; item 2. Tingling or prickling; item 3. Light touching painful; item 4. Sudden pain attacks; item 5. Cold or heat painful; item 6. Numbness; item 7. Slight pressure pain