Validation of the Four-Dimensional Symptom Questionnaire (4DSQ) in a mental health setting

Figures & data

Table 1. Demographic variables, mean 4DSQ scores, and reliability (Cronbach’s alpha and McDonald’s omega) of the US sample (N = 159) and the Dutch sample (N = 159)

	M (SD)			Cronbach’s alpha (95% CI)		McDonald’s omega (95% CI)
	US sample	Dutch sample	p	US sample	Dutch sample	US sample	Dutch sample
Age	32.92 (10.10)	28.82 (9.69)	0.000^a
4DSQ Distress (0–32)^c	12.55 (7.91)	11.57 (8.70)	0.153^b	0.95 [0.93, 0.96]	0.96 [0.95, 0.97]	0.95 [0.93, 0.96]	0.96 [0.95, 0.97]
4DSQ Depression (0–12)^c	1.75 (2.79)	2.02 (2.96)	0.582^b	0.95 [0.94, 0.96]	0.96 [0.95, 0.97]	0.95 [0.94, 0.96]	0.96 [0.95, 0.97]
4DSQ Anxiety (0–24)^c	3.56 (4.51)	3.40 (4.70)	0.609^b	0.94 [0.93, 0.96]	0.96 [0.95, 0.97]	0.94 [0.93, 0.96]	0.96 [0.95, 0.97]
4DSQ Somatization (0–32)^c	6.52 (5.64)	8.23 (6.08)	0.005^b	0.91 [0.89, 0.93]	0.92 [0.90, 0.93]	0.92 [0.90, 0.93]	0.91 [0.89, 0.93]

Note. ^at-test; ^bMann–Whitney U test; ^cscale range.

4DSQ, Four-Dimensional Symptom Questionnaire; 95% CI, 95% confidence interval.

Table 2. Goodness of fit indices of the multi-group CFA for one-factor models fitted to the data of each scale depending on residual correlations allowed

	CFI	TLI	RMSEA	90% CI	Items needing residual correlations
4DSQ Distress	0.983	0.980	0.112	0.101–0.122	–
	0.992	0.991	0.077	0.066–0.089	47–48
	0.996	0.995	0.057	0.043–0.069	47–48, 20–39
4DSQ Depression	1.000	1.000	0.000	0.000–0.068	–
4DSQ Anxiety^a	1.000	1.000	0.000	0.000–0.025	–
4DSQ Somatization	0.977	0.974	0.072	0.061–0.084	–
	0.983	0.980	0.063	0.051–0.075	12–13
	0.987	0.984	0.056	0.042–0.069	12–13, 4–5

Note. ^afit indices were the same for both converged models, excluding item 18 or item 21 due to multicollinearity.

4 DSQ, Four-Dimensional Symptom Questionnaire; CFI, comparative fit index; TLI, Tucker–Lewis index; RMSEA, root-mean-square error of approximation; 90% CI, 90% confidence interval of the RMSEA.

Table 3. Items identified with significant differential item functioning (DIF)

	Item no.	Short Description	M-H method^a	HOLR method^b	DIF type	Direction of DIF^c
4DSQ Distress	22	Lack of energy	0.34	4.30	Uniform	+
4DSQ Anxiety	24	Anxiety or panic attacks	0.35	9.20	Uniform	+
	27	Frightened		2.94	Uniform	-
	42	Afraid of anything when there was no need		2.95	Uniform	-
	45	Threatened by unknown danger		3.50	Non-uniform	?
4DSQ Somatization	6	Excessive sweating	−0.21	4.01	Uniform	-
	14	Tingling in the fingers		3.62	Uniform	-
	15	Pressure or a tight feeling in the chest	0.17	3.60	Uniform	+

Note. ^aM-H method: standardized mean differences (SMD) calculated with Mantel–Haenszel method. ^bHOLR method: Difference in R² (ΔR²) calculated with hybrid ordinal logistic regression (*100). ^cDirection of DIF: the item is more severe or more difficult to reply (-)/less severe or easier to reply (+)/partly less or more severe (?) for US participants.

4DSQ, Four-Dimensional Symptom Questionnaire.

Table 4. Differences in cutoff points according to differential test functioning (DTF)

	Dutch cutoff value		Predicted US sum score
	Moderate	Severe	Moderate	Severe
4DSQ Distress	11.00	21.00	11.57	21.27
4DSQ Anxiety	4.00	10.00	3.90	9.70
4DSQ Somatization	11.00	21.00	10.51	20.58

Note. 4DSQ, Four-Dimensional Symptom Questionnaire.

Table 5. Pearson product–moment correlation coefficients and beta coefficients (linear multivariate regression analysis) indicating relationships between 4DSQ and OQ-45 total score and subscale scores (n = 150)

	Correlation			Regression
	OQ-45 Symptom distress r	OQ-45 Interpersonal relationship r	OQ-45 Social role r	OQ-45 Symptom distress β	OQ-45 Interpersonal relationshipβ	OQ-45 Social role β
4DSQ Distress	.78***	.52***	.55***	.491***	.399***	.440***
4DSQ Depression	.56***	.42***	.42***	.100	.145	.107
4DSQ Anxiety	.62***	.38***	.36***	.115	.056	−.050
4DSQ Somatization	.66***	.35***	.43***	.222**	−.010	.112
Adjusted R^2				.648***	.288***	.298***

Notes. 4DSQ ,Four-Dimensional Symptom Questionnaire, OQ-45, Outcome Questionnaire-45. ***p< 0.001, **p< 0.01.

Table 6. Differences in 4DSQ between patients diagnosed with a depressive disorder or anxiety disorder and another mental health condition

	M	SD	M	SD	F (1,78)	p
	Depressive disorder + (n = 18)		Depressive disorder – (n = 62)
4DSQ Distress	15.11	5.35	11.11	6.94	5.08	0.027
4DSQ Depression	1.89	2.45	1.34	2.19	0.84	0.363
4DSQ Anxiety	4.61	4.68	3.21	4.05	1.56	0.216
4DSQ Somatization	9.22	4.97	6.52	5.73	3.30	0.073
	Anxiety disorder + (n = 18)		Anxiety disorder – (n = 62)
4DSQ Distress	13.78	6.48	11.50	6.85	1.58	0.212
4DSQ Depression	1.11	1.53	1.56	2.41	0.57	0.454
4DSQ Anxiety	5.44	5.14	2.97	3.77	5.07	0.027
4DSQ Somatization	8.50	7.09	6.73	5.16	1.38	0.243

Notes. Depressive disorder/anxiety disorder ± = criteria of DSM-IV mood/anxiety disorder met/not met.

4DSQ, Four-Dimensional Symptom Questionnaire.

Table 7. Logistic regression analysis with mood disorder or anxiety disorder as dependent variable and 4DSQ scores as independent variables (n = 60)

	Odds ratio	95% CI	p
Dependent variable: Diagnosis mood disorder
Initial model: Chi^2(4) = 5.36, p = .252, Nagelkerkes R^2 = 0.099
4DSQ Distress	1.11	0.96, 1.29	0.161
4DSQ Depression	0.95	0.73, 1.24	0.726
4DSQ Anxiety	0.96	0.81, 1.14	0.628
4DSQ Somatization	1.02	0.99, 1.16	0.762
Final model: Chi^2(1) = 4.98, p = .026, Nagelkerkes R^2 = 0.092
4DSQ Distress	1.10	1.01, 1.19	0.032
Dependent variable: Diagnosis anxiety disorder
Initial model: Chi^2(4) = 7.16, p = .128, Nagelkerkes R^2 = 0.130
4DSQ Distress	0.99	0.84, 1.17	0.925
4DSQ Depression	0.73	0.47, 1.14	0.169
4DSQ Anxiety	1.16	0.96, 1.40	0.116
4DSQ Somatization	1.04	0.90, 1.22	0.573
Final model: Chi^2(1) = 4.53, p = .033, Nagelkerkes R^2 = 0.084
4DSQ Anxiety	1.14	1.01, 1.28	0.033

Figure 1. Receiver operating characteristic (ROC) curves of 4DSQ scales with respect to detecting a mood disorder diagnosis in an outpatient psychotherapy sample (n = 60). AUC=area under the curve, 95%CI=95% confidence interval

Figure 2. Receiver operating characteristic (ROC) curves of 4DSQ scales with respect to detecting an anxiety disorder diagnosis in an outpatient psychotherapy sample (n = 60). AUC=area under the curve, 95%CI=95% confidence interval