Cross-cultural validity and psychometric properties of the International Trauma Questionnaire in a clinical refugee sample

Figures & data

Table 1. Demographic characteristics of the study sample.

Characteristic	n	%
Age^a
17–37 years	165	33.7
38–47 years	172	35.1
48–76 years	153	32.1
Gender^a
Male	264	53.9
Female	226	46.1
Diagnosis^b
No PTSD	49	10.0
PTSD	103	21.0
CPTSD	338	69.0
Country of origin
Syria	247	50.4
Bosnia	67	13.7
Afghanistan	42	8.6
Kosovo	31	6.3
Lebanon	18	3.7
Iraq	16	3.3
Iran	10	2.0
None of the above	59	12.0
ITQ language/spoken language^a
Danish/Danish	205	41.8
Arabic/Arabic	183	37.3
Bosnian/Bosnian	32	6.5
Danish/Arabic	70	14.3
Assistance from interpreter or clinician^a
None	97	19.8
Few clarifications	181	36.9
Read aloud and many clarifications	73	14.9
Read aloud and formulated answers	106	21.6
Missing	33	6.7
Time since trauma exposure^a
Up to 5 years	121	24.7
5–10 years	136	27.8
≥ 10 years	233	47.6

Note: ^aExogeneous variables included in the differential item functioning (DIF) analysis. ^bBy the suggested International Trauma Questionnaire (ITQ) diagnosis algorithms.

PTSD, post-traumatic stress disorder; CPTSD, complex post-traumatic stress disorder.

Table 2. Type and prevalence of traumatic events in the study sample.

Type of traumatic event	Frequency
War and flight	363
Imprisonment or kidnapping	42
Torture (physical and psychological)	18
Violence	13
Witnessing violence (including executions)	11
Loss and death among close relations	7
Rape or sexual abuse	7
Social problems (e.g. issues regarding legal stay in Denmark, family disputes)	6
Symptoms (e.g. reporting depression as the trauma)	4
Other	19

Note: The categorization is based on what the patients filled out as the first, and sometimes only, trauma in the open-ended question in the International Trauma Questionnaire (ITQ). Thus, if the patient has reported violence as the first trauma, this was categorized as violence. The table cannot be considered to provide an adequate account, as, for example, the clinicians know that more than 18 people in the group has suffered torture. We nevertheless chose this categorization, as the ITQ only asks for a single trauma, and even an attempt to categorize multiple traumas would thus also have been incomplete.

Table 3. Percentage distribution of responses to post-traumatic stress disorder (PTSD) and disturbances in self-organization (DSO) items of the International Trauma Questionnaire (ITQ).

PTSD items	Not at all	A little bit	Some what	Quite a bit	A lot
Re-experiencing
p1. Upsetting dreams that replay part of the event or are clearly related to the event?	3.1	3.9	14.9	30.6	47.6
p2. Powerful images or memories that sometimes come into your mind in which you feel the event?	3.9	5.1	13.7	33.3	44.1
Avoidance
p3. Avoiding internal reminders of the stressful event (for example, thoughts, feelings, or physical sensations)?	2.9	6.3	11.6	31.0	48.2
p4. Avoiding external reminders of the stressful event (for example, people, places, conversations, objects, activities, or situations)?	6.7	6.1	11.0	29.6	46.5
Sense of threat
p5. Being ‘super-alert,’ watchful, or on guard?	5.3	5.1	10.2	26.5	52.9
p6. Feeling jumpy or easily startled?	4.3	4.5	8.4	28.6	54.3
DSO items	Not at all	A little bit	Some what	Quite a bit	A lot
Affective dysregulation
c1. When I am upset, it takes me a long time to calm down	3.5	10.6	15.5	34.3	36.1
c2. I feel numb or emotionally shut down	9.8	6.3	12.2	31.2	40.4
Negative self-concept
c3. I feel like a failure	18.6	8.8	15.5	22.4	34.7
c4. I feel worthless	19.4	10.4	14.9	23.1	32.2
Disturbed relationship
c5. I feel distant or cut off from people	10.2	7.8	16.1	27.3	38.6
c6. I find it hard to stay emotionally close to people	11.6	9.0	14.5	28.6	36.3

Note: Valid percentages are reported. Scores ranged from 0 = not at all to 4 = extremely.

Table 4. Distribution of degree of interpreter assistance provided to patients within language groups.

ITQ language/spoken language	Degree of interpreter assistance
	None	Few clarifications	Read aloud and many clarifications	Read aloud and helped formulating answers	Row total
Danish/Danish	56 (29.3%)	70 (36.6%)	31 (16.2%)	34 (17.8)	191 (100.0%)
Arabic/Arabic	27 (15.3%)	70 (39.5%)	26 (14.7%)	54 (30.5%)	177 (100.0%)
Bosnian/Bosnian	6 (22.2%)	8 (29.6%)	8 (29.6%)	5 (18.5%)	27 (100.05%)
Danish/Arabic	8 (12.9%)	33 (53.2%)	8 (12.9%)	13 (21.0%)	62 (100.0%)
Column total	97 (21.2%)	181 (39.6%)	73 (16.0%)	106 (23.2%)	457 (100.0%)

Note: ITQ, International Trauma Questionnaire.

Figure 1. Final graphical log-linear Rasch models for the post-traumatic stress disorder (PTSD) scale (top) and the disturbances in self-organization (DSO) scale (bottom). Note: γ-correlations are partial Goodman and Kruskal’s rank correlations for ordinal data. Lang, language versions; TimeT, time since trauma exposure.

Table 5. Global tests of homogeneity and invariance for the post-traumatic stress disorder (PTSD) and disturbances in self-organization (DSO) scales under the Rasch model (RM) and final graphical log-linear Rasch model (GLLRM).

Test	PTSD (RM)			PTSD (GLLRM)^a			DSO (RM)			DSO (GLLRM)^b
	CLR	df	p	CLR	df	p	CLR	df	p	CLR	df	p
Global homogeneity	56.1	23	< .001^d	77.2	81	.600	45.5	23	.003^d	80.1	70	.193
Global invariance relative to:
Language groups	117.9	69	< .001^d	242.3	243	.501	134	69	< .001^d	251.9	210	.025^e
Gender	36.9	23	.036^d	72.4	73	.499	14	23	.926	71.7	70	.421
Age groups	49.2	46	.345	172.6	162	.269	53.7	46	.204	157.9	140	.143
Time since trauma	51.6	46	.263	178.8	138	.011^e	53.4	46	.211	160.3	140	.115
Assistance^c	–	–	–	295.0	243	.013^f	–	–	–	228.2	207	.148

Note: ^aModel assumes local dependence between items p1 and p2, p3 and p4, and p5 and p6, as well as gender differential item functioning (DIF) on item p6 and DIF relative to time since trauma on item p2.

^b Model assumes local dependence between items c3 and c4, items c5 and c6, and items c2 and c6.

^c Tests of invariance relative to assistance from interpreter or clinician were conducted in separate analyses with the final GLLRMs (notes a and b), owing to the lower n of 457. Item-level tests of DIF are included in Table S8 in the Supplementary material.

CLR, conditional likelihood ratio; df, degrees of freedom.

The global homogeneity test compares item parameters in approximately equal-sized groups of high- and low-scoring participants; Assistance: assistance from interpreter or clinician. The critical limits for the p-values after adjusting for false discovery rates were: ^d5% and 1% limit unaltered, ^e5% limit p = .010, 1% limit p = .002; ^f5% limit p = .0083, 1% limit p = .0017.

Table 6. Conversion of post-traumatic stress disorder (PTSD) raw scores to weighted maximum likelihood estimates of person parameters and adjustment of the raw score for differential item functioning (DIF) relative to gender and time since trauma, in (A) men and (B) women.

(A) Men
Reference group: Men, up to 5 years since trauma					Men, 5–10 years since trauma					Men, ≥ 10 years since trauma
Score	p.p.	p.p. SEM	Bias	Score SEM	DIF adj. score	p.p.	p.p. SEM	Bias	Score SEM	DIF adj. score	p.p.	p.p. SEM	Bias	Score SEM
0	−2.483	0.680	0.439	0.82	0^a	−2.655	0.705	0.450	0.79	0^a	−2.736	0.726	0.460	0.77
1	−1.607	0.583	0.071	1.46	1.14	−1.729	0.615	0.069	1.39	1.02	−1.768	0.632	0.069	1.37
2	−1.234	0.532	0.010	1.90	2.10	−1.326	0.561	0.010	1.81	2.01	−1.348	0.571	0.009	1.80
3	−1.002	0.476	−0.004	2.27	2.99	−1.071	0.501	−0.004	2.15	3.00	−1.087	0.504	−0.004	2.15
4	−0.833	0.427	−0.008	2.57	3.86	−0.884	0.448	−0.006	2.43	3.99	−0.898	0.448	−0.007	2.45
5	−0.701	0.388	−0.008	2.82	4.73	−0.735	0.405	−0.006	2.68	4.98	−0.751	0.403	−0.007	2.70
6	−0.591	0.356	−0.007	3.04	5.62	−0.612	0.371	−0.006	2.88	5.98	−0.630	0.369	−0.007	2.92
7	−0.496	0.332	−0.006	3.22	6.53	−0.504	0.345	−0.005	3.06	6.98	−0.527	0.342	−0.006	3.11
8	−0.412	0.313	−0.005	3,37	7.48	−0.409	0.325	−0.004	3.21	8.00	−0.435	0.322	−0.005	3.26
9	−0.335	0.299	−0.004	3.49	8.46	−0.322	0.310	−0.004	3.33	9.002	−0.352	0.307	−0.004	3.39
10	−0.263	0.289	−0.003	3.58	9.57	−0.241	0.299	−0.003	3.42	10.04	−0.276	0.296	−0.004	3.48
11	−0.194	0.283	−0.002	3.64	10.52	−0.165	0.292	−0.002	3.49	11.08	−0.203	0.289	−0.003	3.55
12	−0.128	0.281	−0.001	3.67	11.58	−0.092	0.287	−0.002	3.54	12.11	−0.133	0.286	−0.002	3.59
13	−0.062	0.281	0.000	3.67	12.67	−0.020	0.286	−0.001	3.56	13.16	−0.065	0.285	−0.001	3.61
14	0.003	0.285	0.001	3.64	13.77	0.051	0.288	−0.000	3.56	14.20	0.003	0.289	0.001	3.59
15	0.071	0.293	0.003	3.59	14.88	0.122	0.292	0.001	3.53	15.25	0.072	0.295	0.002	3.54
16	0.141	0.304	0.004	3.50	15.99	0.194	0.301	0.002	3.47	16.29	0.144	0.306	0.004	3.47
17	0.215	0.320	0.006	3.39	17.09	0.269	0.312	0.003	3.38	17.32	0.219	0.321	0.006	3.36
18	0.296	0.340	0.008	3.23	18.17	0.349	0.327	0.005	3.26	18.35	0.301	0.341	0.008	3.21
19	0.388	0.366	0.010	3.04	19.23	0.436	0.345	0.005	3.10	19.36	0.393	0.366	0.009	3.03
20	0.495	0.398	0.010	2.79	20.26	0.534	0.364	0.004	2.89	20.36	0.499	0.395	0.010	2.79
21	0.630	0.436	0.007	2.49	21.25	0.650	0.385	−0.001	2.63	21.33	0.632	0.431	0.006	2.50
22	0.814	0.478	−0.008	2.11	22.21	0.801	0.403	−0.019	2.29	22.27	0.812	0.470	−0.008	2.13
23	1.118	0.523	−0.065	1.61	23.12	1.032	0.419	−0.075	1.82	23.17	1.107	0.510	−0.065	1.64
24	1.942	0.648	−0.431	0.87	24^a	1.614	0.519	−0.361	1.06	24^a	1.900	0.633	−0.423	0.89
(B) Women
Women, up to 5 years since trauma					Women, 5–10 years since trauma					Women, ≥ 10 years since trauma
DIF adj. score	p.p.	p.p. SEM	Bias	Score SEM	DIF adj. score	p.p.	p.p. SEM	Bias	Score SEM	DIF adj. score	p.p.	p.p. SEM	Bias	Score SEM
0^a	−2.442	0.685	0.441	0.82	0^a	−2.621	0.709	0.451	0.79	0^a	−2.709	0.732	0.462	0.77
0.96	−1.557	0.589	0.071	1.44	1.09	−1.688	0.622	0.070	1.38	0.97	−1.727	0.641	0.069	1.36
1.86	−1.178	0.537	0.011	1.89	1.96	−1.278	0.569	0.010	1.79	1.87	−1.301	0.578	0.010	1.78
2.73	−0.941	0.479	−0.004	2.25	2.75	−1.015	0.507	−0.003	2.12	2.74	−1.031	0.510	−0.004	2.13
3.60	−0.770	0.429	−0.008	2.56	3.53	−0.821	0.452	−0.006	2.40	3.60	−0.837	0.451	−0.007	2.43
4.48	−0.636	0.389	−0.008	2.82	4.30	−0.667	0.408	−0.006	2.65	4.47	−0.686	0.406	−0.007	2.69
5.38	−0.526	0.357	−0.007	3.03	5.09	−0.540	0.373	−0.006	2.86	5.36	−0.563	0.370	−0.007	2.91
6.28	−0.431	0.333	−0.006	3.22	5.91	−0.430	0.346	−0.005	3.05	6.27	−0.458	0.344	−0.006	3.10
7.21	−0.346	0.314	−0.005	3.36	6.76	−0.334	0.326	−0.005	3.20	7.20	−0.366	0.323	−0.006	3.25
8.15	−0.269	0.300	−0.004	3.48	7.66	−0.246	0.310	−0.004	3.33	8.15	−0.283	0.308	−0.005	3.38
9.12	−0.197	0.290	−0.003	3.57	8.60	−0.166	0.299	−0.004	3.43	9.14	−0.206	0.297	−0.004	3.58
10.10	−0.128	0.284	−0.002	3.62	9.59	−0.090	0.291	−0.003	3.51	10.15	−0.134	0.290	−0.003	3.55
11.10	−0.061	0.281	−0.001	3.66	10.62	−0.018	0.286	−0.002	3.57	11.18	−0.064	0.286	−0.002	3.59
12.12	0.005	0.281	0.000	3.66	11.70	0.052	0.284	−0.002	3.59	12.24	0.005	0.285	−0.001	3.60
13.15	0.071	0.285	0.001	3.63	12.83	0.121	0.286	−0.001	3.59	13.32	0.073	0.288	0.001	3.59
14.20	0.139	0.292	0.003	3.58	13.99	0.190	0.290	0.001	3.57	14.43	0.142	0.294	0.002	3.54
15.27	0.210	0.303	0.004	3.50	15.17	0.260	0.298	0.002	3.51	15.55	0.214	0.305	0.004	3.47
16.35	0.285	0.318	0.006	3.38	16.37	0.333	0.309	0.003	3.42	16.67	0.289	0.319	0.005	3.36
17.44	0.367	0.338	0.007	3.23	17.58	0.410	0.323	0.005	3.30	17.81	0.371	0.338	0.007	3.22
18.54	0.458	0.363	0.009	3.04	18.76	0.494	0.339	0.005	3.13	18.93	0.462	0.361	0.009	3.04
19.64	0.565	0.393	0.009	2.81	19.92	0.590	0.358	0.004	2.92	20.04	0.567	0.389	0.009	2.81
20.75	0.695	0.427	0.005	2.52	21.03	0.704	0.376	−0.002	2.66	21.12	0.696	0.421	0.005	2.53
21.85	0.872	0.464	−0.009	2.15	22.09	0.852	0.393	−0.021	2.31	22.16	0.869	0.455	−0.010	2.16
22.94	1.157	0.501	−0.065	1.66	23.08	1.080	0.406	−0.079	1.84	23.12	1.146	0.488	−0.067	1.68
24^a	1.934	0.624	−0.419	0.90	24^a	1.625	0.500	−0.350	1.10	24^a	1.893	0.608	−0.411	0.92

Note: ^aExtreme scores cannot be DIF adjusted.

p.p., person parameter; SEM, standard error of measurement.

Table 7. Conversion of disturbances in self-organization (DSO) raw scores to weighted maximum likelihood estimates of person parameters.

Score	p.p.	p.p. SEM	Bias	Score SEM
0	−2.732	0.749	0.476	0.75
1	−1.710	0.634	0.064	1.39
2	−1.302	0.563	0.006	1.85
3	−1.055	0.494	−0.007	2.23
4	−0.881	0.438	−0.010	2.54
5	−0.748	0.396	−0.010	2.80
6	−0.639	0.363	−0.009	3.02
7	−0.544	0.338	−0.007	3.19
8	−0.460	0.320	−0.005	3.32
9	−0.382	0.307	−0.004	3.42
10	−0.308	0.298	−0.002	3.49
11	−0.236	0.292	−0.001	3.52
12	−0.165	0.291	0.000	3.53
13	−0.093	0.292	0.002	3.51
14	−0.019	0.297	0.003	3.46
15	0.057	0.306	0.004	3.38
16	0.139	0.319	0.005	3.28
17	0.228	0.337	0.006	3.14
18	0.327	0.361	0.007	2.97
19	0.442	0.392	0.007	2.77
20	0.578	0.431	0.007	2.53
21	0.750	0.478	0.004	2.24
22	0.982	0.530	−0.011	1.90
23	1.344	0.574	−0.070	1.46
24	2.199	0.669	−0.433	0.83

Note: p.p., person parameter; SEM, standard error of measurement.

Table 8. Comparison of observed and differential item functioning (DIF)-adjusted mean post-traumatic stress disorder (PTSD) scores for groups defined by gender and time since trauma.

DIF group^a (n)	Observed scores		Adjusted scores
	Mean	SE	Mean	SE	Bias^a
Gender^b
Male (264)	18.63	0.29	18.75	0.29	−.12
Female (226)	19.07	0.27	18.79	0.29	.28
Time since trauma^c
Up to 5 years (121)	18.04	0.43	17.88	0.44	.16
5–10 years (136)	18.59	0.39	18.41	0.42	.18
≥ 10 years (233)	19.39	0.26	19.45	0.27	−.06

Note: ^aAs the PTSD scale is affected by DIF from more than once source, any reference group within a DIF variable is adjusted to account for the other sources of DIF, and thus all groups are biased if not adjusted.

^b Differences in observed mean scores (χ²(1) = 1.3, p = .258) and adjusted mean scores (χ²(1) = 0.0, p = .917).

^c Differences in observed mean scores (χ²(2) = 8.1, p = .018) and adjusted mean scores (χ²(2) = 10.9, p = .004).

SE, standard error.

Table 9. Targeting and reliability of the post-traumatic stress disorder (PTSD) and disturbances in self-organization (DSO) scales.

	Theta								Score
Scale, gender, and time since trauma subgroups^a (n)	Target	Mean	TI mean	TI max	TI Target index	RMSE mean	RMSE min	RMSE target index	Target	Mean	Mean SEM	r^b
PTSD scale
Men
Time up to 5 years (72)	−0.09	−0.73	7.654	13.484	0.568	0.416	0.272	0.655	12.62	6.75	2.67	0.726
Time 5–10 years (68)	0.01	−1.01	5.772	12.698	0.455	0.477	0.281	0.589	13.36	5.40	2.27	0.779
Time ≥ 10 years (124)	−0.07	−1.09	5.443	12.982	0.419	0.491	0.277	0.565	12.95	4.56	2.23	0.629
Women
Time up to 5 years (49)	−0.02	−0.88	6.230	13.397	0.465	0.453	0.273	0.603	12.60	4.80	2.41	0.548
Time 5–10 years (68)	0.09	−0.83	6.293	12.936	0.486	0.455	0.278	0.612	13.52	5.43	2.42	0.637
Time ≥ 10 years (109)	0.00	−1.05	5.330	12.982	0.411	0.499	0.278	0.556	12.98	4.68	2.19	0.696
DSO scale
Full sample (490)	−0.18	0.33	7.649	12.472	0.613	0.410	0.283	.690	11.78	3.53	2.53	0.792

Note: ^aTargeting and reliability is provided for groups defined by differential item functioning (DIF) variables. ^bWeighted mean reliability of the PTSD scale across the six subgroups = 0.67.

TI, test information; RMSE, root mean squared error of the estimated theta score; SEM, standard error of measurement of the observed score; r, reliability.

Data availability statement

Data can be made available for research purposes upon reasonable request to the corresponding author.