Susceptibility of functional impairment scales to noncredible responses in the clinical evaluation of adult ADHD

Figures & data

Table 1. Characteristics of participants.

	CG	ADHD	SG
n	142	62	330
Age (in years, M ± SD)	31.0 ± 12.3	36.2 ± 11.1	26.8 ± 10.0
Gender (female/male)	66/76	26/36	189/141
Education (in years, M ± SD)	14.0 ± 2.6	11.8 ± 3.3	16.0 ± 2.5

Note:

CG = Control group; ADHD = Patients with ADHD; SG = Simulation group.

Table 2. Comparison of Weiss Functional Impairment Rating Scale (WFIRS) scores between healthy control participants (CG), patients with ADHD (ADHD), and the simulation group (SG).

Domain of impairment	CG (n = 142)	ADHD (n = 62)	SG (n = 330)	Omnibus test^a	Pairwise group comparison^b
					CG vs. ADHD		CG vs. SG		ADHD vs. SG
	M ± SD	M ± SD	M ± SD	Χ^2 (df), p	Z, p	Cohen’s d	Z, p	Cohen’s d	Z, p	Cohen’s d
Family	.57 ± .49	1.37 ± .63	1.67 ± .57	223.7 (2), <.001	6.89, <.001^*	1.49	14.96, <.001^*	2.01	3.27, .001 ^*	.52
Work	.46 ± .49	1.28 ± .71	1.75 ± .54	248.3 (2), <.001	6.14, <.001^*	1.45	15.72, <.001^*	2.46	4.37, <.001^*	.83
Life skills	.67 ± .46	1.36 ± .62	1.55 ± .51	194.8 (2), <.001	7.08, <.001^*	1.34	13.94, <.001^*	1.78	2.32, .020	.36
Self-concept	.66 ± .60	1.87 ± .86	1.65 ± .68	166.4 (2), <.001	12.10, <.001^*	1.76	9.55, <.001^*	1.51	1.73, .084	−.31
Social	.54 ± .47	1.26 ± .68	1.58 ± .55	215.4 (2), <.001	6.76, <.001^*	1.33	14.68, <.001^*	1.97	3.20, .001^*	.56
Risk	.52 ± .45	.78 ± .52	1.34 ± .57	192.5 (2), <.001	2.97, .003^*	.55	13.38, <.001^*	1.53	6.48, <.001^*	1.00

Notes:

CG = Control group; ADHD = Patients with ADHD; SG = Simulation group;

^a Kruskal–Wallis Test.

^b Dunn’s post hoc test.

^* Statistical significant at Bonferroni corrected significance level of .05/6 = .008.

Figure 1. Receiver operating characteristic (ROC) curves indicating diagnostic accuracies of four scales of the Weiss Functional Impairment Rating Scale (WFIRS) in identifying feigned ADHD (n = 330) relative to genuine ADHD (n = 62).

Table 3. Classification accuracies of four scales of the Weiss Functional Impairment Rating Scale (WFIRS) in identifying feigned ADHD (n = 330) relative to genuine ADHD (n = 62).

Domain	Cutoff	Specificity (%)	Sensitivity (%)	PPV (%)	NPV (%)
Family	2.14	89.7	17.1	88.9	16.8
Work	2.29	89.7	13.5	88.0	19.3
Social	2.12	89.7	13.8	88.2	16.4
Risk	1.42	89.7	47.7	95.7	24.1

Note:

PPV = Positive predictive value; NPV = Negative predictive value.