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

Table 3 Item fit statistics

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

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

ISSN: 1477-7525