The significant others’ responses to trauma scale (SORTS): applying factor analysis and item response theory to a measure of PTSD symptom accommodation

Figures & data

Table 1. Demographics of SORTS respondents.

	EFA sample (n = 272) n (%)	CFA sample (n = 443) n (%)	Total sample (n = 715) n (%)
Mean age (SD)	30.49 (5.51)	37.23 (12.20)	34.10 (10.24)
IP is a service member/veteran
Yes	272 (100%)	283 (63.9%)	555 (77.6%)
No	0 (0%)	51 (11.5%)	51 (7.1%)
Unknown	0 (0%)	109 (24.6%)	109 (15.2%)
FM is a woman
Yes	272 (100%)	341 (77.0%)	613 (85.7%)
No	0 (0%)	88 (19.9%)	88 (12.3%)
Unknown	0 (0%)	14 (3.2%)	14 (2.0%)
FM is IP’s romantic partner
Yes	272 (100%)	348 (78.6%)	620 (86.7%)
No	0 (0%)	90 (20.3%)	90 (12.6%)
Unknown	0 (0%)	5 (1.1%)	4 (0.6%)
FM race^a
White	236 (86.8%)	208 (47.0%)	444 (62.1%)
Black/African American/African	14 (5.1%)	39 (8.8%)	53 (7.4%)
American Indian/Alaskan Native/Indigenous Canadian	4 (1.5%)	6 (1.4%)	10 (1.4%)
Asian/Asian American/South Asian/Native Hawaiian/Pacific Islander	7 (2.6%)	28 (6.3%)	35 (4.9%)
Biracial/Other	14 (5.1%)	31 (7.0%)	45 (6.3%)
Unknown	0 (0%)	131 (29.6%)	131 (18.3%)
FM ethnicity
Hispanic	27 (9.9%)	25 (5.6%)	52 (7.3%)
Non-Hispanic	245 (90.1%)	132 (29.8%)	377 (52.7%)
Unknown	0 (0%)	286 (64.6%)	286 (40.0%)
SORTS collected as research	272 (100%)	314 (70.9%)	586 (82.0%)
SORTS collected in routine clinical care	0 (0.0%)	129 (29.1%)	129 (18.0%)

Note. SORTS = Significant Others’ Responses to Trauma Scale. EFA = exploratory factor analysis; CFA = confirmatory factor analysis; IP = identified patient; FM = family member.

^a Some studies/clinics permitted participants to select more than one racial identity, so totals may exceed 100%

Table 2. Standardised exploratory factor analysis loadings of a two-factor SORTS model with continuous scores.

	Managing explosivity/conflict	Avoidance and changing routine
	(Factor 1)	(Factor 2)
1. Avoid [Name] because of his/her irritable or angry mood?	0.823	0.014
2. Avoid being physically close with [Name] because of his/her discomfort?	0.285*	0.345
3. Cancel or rearrange plans or social activities because [Name] did not want to do them?	0.106	0.685
4. Avoid doing things, going places, or seeing people with [Name] that make him/her anxious or uncomfortable?	−0.042	0.803
5. ‘Bite your tongue’ or hold back from trying to discuss any relationship issues with [Name]?	0.899	−0.051
6. Take over a task or chore for [Name] that he/she is uncomfortable doing because of his/her traumatic event?	0.047	0.457
7. Help [Name] with a task because he/she was having trouble concentrating?	0.136	0.505
8. Make excuses to others for [Name]’s behaviour or try to manage his/her relationships with other people?	0.665	0.175*
9. ‘Tiptoe’ around [Name] so as not to anger him/her?	0.908	−0.008
10. Avoid discussing events related to [Name]’s traumatic event(s) in front of him/her to avoid his/her becoming upset?	0.321*	0.374
11. Not share your own feelings or concerns with [Name] due to concerns that he/she would become upset?	0.788	0.033
12. Change your routine due to [Name]’s difficulties?	−0.001	0.806
13. How much have you modified your leisure activities due to [Name]’s difficulties?	−0.001	0.813
14. Give up control to [Name] because of his/her desire to be in charge?	0.642	−0.001

Note. * = significant cross-loading. SORTS = Significant Others’ Responses to Trauma Scale.

Figure 1. Higher-order measurement model of the significant others’ Responses to Trauma Scale with items identified through exploratory factor analysis.

Table 3. Fit statistics for CFA models.

	Chi-sq	CFI	TLI	RMSEA 90% CI	RMSR
Frequency and Distress model	4278.208 (p < .001)	.835	.821	0.155–0.164	N/A
14 items	251.960 (p < .001)	.926	.912	0.063–0.082	0.052
11 items	136.617 (p < .001)	.949	.935	0.057–0.083	0.040
Higher-order model with 11 items	136.617 (p < .001)	.949	.935	0.057–0.083	0.040

Note. CFI = Bentler comparative fit index; TLI = Tucker-Lewis index; RMSEA 90% CI = root mean square error of approximation 90% confidence interval; RMSR = standardised root mean square residual.

Table 4. Correlations among SORTS Factors, PTSD symptoms rated by IP and FM, and relationship satisfaction.

	1	2	3	4	5	6	7	8	9	10	11	12
1. SORTS Factor 1 (anger)	1
2. SORTS Factor 2 (avoid)	.672**	1
3. PCL reexperiencing	.427**	.414**	1
4. PCL avoidance	.403**	.411**	.718**	1
5. PCL numbing	.475**	.467**	.693**	.648**	1
6. PCL hyperarousal	.524**	.449**	.750**	.659**	.725**	1
7. FM-rated PCL reexperiencing	.304**	.398**	.383**	.364**	.334**	.301**	1
8. FM-rated PCL avoidance	.274**	.387**	.367**	.388**	.335**	.321**	.571**	1
9. FM-rated PCL numbing	.295**	.268**	.199*	.241**	.260**	.234**	.374**	.447**	1
10. FM-rated PCL hyperarousal	.501**	.465**	.371**	.419**	.398**	.411**	.672**	.576**	.439**	1
11. FM CSI	−.573**	−.415**	.081	.236	−.024	.204	.177	.402	.282	.459	1
12. IP CSI	−.442**	−.270**	.028	.097	−.211	−.094	−.078	−.201	−.415	−.183	.581**	1

Note. SORTS = Significant Others’ Responses to Trauma Scale. IP = identified patient. FM = family member. PCL = PTSD Checklist-Military Version. CSI = Couple Satisfaction Index. Ns for SORTS correlation with PCL and FM-rated PCL were 228 and 149, respectively. N for SORTS correlation with CSI was 185. Ns for CSI correlation with PCL and FM-rated PCL were 17 and 17, respectively.

Figure 2. Item information curves (IICs) for individual frequency items from the Significant other’s Responses to Trauma Scale (SORTS) loading onto Factor 1 (anger-related accommodation) and factor (anxiety-related accommodation).

Data availability statement

Data used in the present study were aggregated across multiple studies/clinical programmes; as a result of differences in the individual Data Use Agreements that govern this aggregation, the data are not available to outside investigators.