Table 5

Fit statistics after adjustment for cross-cultural DIF in the affected testlets

DomainTestletLocationSEFit residualsχ2p Value
AS
 PainPain–Norway−0.150.03−1.137.760.56
Pain-–Others−0.010.010.4714.700.10
 MovementMovement0.070.01−0.8010.730.29
 FeelingsFeelings0.040.01−0.1816.080.07
 Disease processDisease process−0.140.010.218.110.52
 TreatmentsTreatments0.040.010.837.970.54
 Self-helpSelf-help−0.100.012.045.590.78
 SupportSupport –The Netherlands0.150.04−0.967.180.62
Support–Others0.090.010.7010.020.35
PsA
 PainPain–Austria−0.060.03−1.076.730.46
Pain–Norway−0.700.040.236.540.48
Pain–The Netherlands0.130.03−0.095.690.58
Pain–Others0.080.02−0.575.650.58
 MovementMovement0.200.012.518.280.31
 FeelingsFeelings0.160.012.454.090.77
 Disease processDisease process–Finland−0.150.04−1.934.710.70
Disease process–Others−0.130.01−0.114.990.66
 TreatmentsTreatments–The Netherlands−0.080.030.778.070.33
Treatments–Sweden−0.050.031.355.090.65
Treatments–Others0.140.01−0.277.720.36
 Self-helpSelf-help–The Netherlands−0.220.032.5417.900.01
Self-help–Portugal0.160.030.383.550.83
Self-help–Others−0.050.010.379.730.20
 SupportSupport–Austria0.490.031.374.740.69
Support-–Finland−0.400.05−0.936.530.48
Support–Portugal0.210.030.875.680.58
Support–Others0.250.020.448.690.28
SSc
 PainPain0.060.020.176.930.23
 MovementsMovements0.120.02−0.998.340.14
 FeelingsFeelings0.090.021.793.370.64
 Disease processDisease process−0.210.02−0.0210.970.05
 TreatmentsTreatments–The Netherlands−0.060.031.963.500.62
Treatments–Others0.030.020.745.610.35
 Self-helpSelf-help−0.160.020.774.130.53
 SupportSupport–The Netherlands0.220.041.233.620.61
Support–Others−0.090.031.2810.510.06
SLE
 PainPain0.010.02−0.135.310.50
 MovementMovements–Spain0.030.03−0.434.410.62
Movements–Others0.060.020.052.280.89
 FeelingsFeelings−0.040.022.165.560.47
 Disease processDisease process−0.180.01−0.6012.620.05
 TreatmentsTreatments–Spain0.180.020.274.020.67
Treatments–Others−0.020.020.754.230.65
 Self-helpSelf-help−0.120.020.186.200.40
 SupportSupport0.080.022.059.220.16
FMS
 PainPain−0.040.020.405.380.37
 MovementsMovements−0.040.020.683.560.61
 FeelingsFeelings−0.050.020.793.200.67
 Disease processDisease process−0.130.02−1.246.880.23
 TreatmentsTreatments0.280.021.965.520.36
 Self-helpSelf-help−0.080.020.138.720.12
 SupportSupport–The Netherlands0.060.02−0.146.120.29
  • AS, ankylosing spondylitis; DIF, differential item functioning; FMS, fibromyalgia syndrome; p, Bonferroni-adjusted χ2 probability (non-significant p=Fit to the model); PsA, psoriatic arthritis; SLE, systemic lupus erythematosus; SSc, systemic sclerosis.