Psychometric evaluation of the Sheehan Disability Scale in adult patients with attention-deficit/hyperactivity disorder

Figures & data

Table 1 SDS descriptive statistics

SDS item/subscale	N	Mean (SD)	Median	Range	Missing (%)
Item 1: ADHD symptoms disrupting work/school
Baseline	428	7.3 (2.1)	8.0	0–10	34 (7.9)
Week 9	424	5.2 (2.7)	5.0	0–10	38 (9.0)
Change (baseline to week 9)	400	−2.0 (2.9)	−2.0	−10 to 10	62 (15.5)
Item 2: ADHD symptoms disrupting social life
Baseline	456	6.2 (2.3)	6.0	0–10	6 (1.3)
Week 9	447	4.6 (2.7)	4.0	0–10	15 (3.4)
Change (baseline to week 9)	446	−1.6 (2.9)	−1.0	−10 to 7	16 (3.6)
Item 3: ADHD symptoms disrupting family life/home responsibilities
Baseline	445	7.0 (2.2)	7.0	0–10	17 (3.8)
Week 9	440	5.1 (2.7)	5.0	0–10	22 (5.0)
Change (baseline to week 9)	434	−1.9 (2.8)	−1.0	−10 to 7	28 (6.5)
Item 4: days lost at school or work in the last weeka
Baseline	398	1.4 (2.0)	0.0	0–7	64 (16.1)
Week 9	395	0.8 (1.6)	0.0	0–7	67 (17.0)
Change (baseline to week 9)	358	−0.5 (1.9)	0.0	−7 to 7	104 (29.1)
Item 5: days underproductive at school or work in the last weekb
Baseline	414	3.5 (2.4)	3.0	0–7	48 (11.6)
Week 9	405	2.2 (2.4)	2.0	0–7	57 (14.1)
Change (baseline to week 9)	379	−1.3 (2.5)	−1.0	−7 to 6	83 (21.9)
SDS total score
Baseline	417	20.5 (5.5)	21.0	0–30	45 (10.8)
Week 9	417	14.9 (7.6)	15.0	0–30	45 (10.8)
Change (baseline to week 9)	388	−5.4 (7.8)	−4.0	−30 to 17	74 (19.1)

Notes:

a Two out-of-range responses were excluded at baseline (20, 25) and three out-of-range responses were excluded at week 9 (8, 10);

b four out-of-range responses were excluded from item 5 at baseline (10, 10, 14, 35), and four were excluded at week 9 (8, 10, 10, 11).

Abbreviations: ADHD, attention-deficit/hyperactivity disorder; SD, standard deviation; SDS, Sheehan Disability Scale.

Table 2 SDS inter-item correlations

SDS item/subscale	Baseline				Week 9
	Item 1	Item 2	Item 3	Item 4	Item 1	Item 2	Item 3	Item 4
Item 1: work/school
Item 2: social life	0.53*				0.79*
Item 3: family life/home responsibilities	0.54*	0.62*			0.76*	0.77*
Item 4: days lost	0.31*	0.31*	0.32*		0.43*	0.38*	0.40*
Item 5: days underproductive	0.38*	0.23*	0.31*	0.35*	0.61*	0.50*	0.54*	0.48*

Notes: Correlation coefficients involving items 4 or 5 are Spearman coefficients, and the remaining correlations are Pearson coefficients.

* P<0.01.

Abbreviation: SDS, Sheehan Disability Scale.

Table 3 SDS test-retest reliability: item-level and total SDS

SDS item/subscale	ICC coefficient (95% CI), n
Screening to baseline
Item 1: work/school	0.59 (0.53–0.65), 413
Item 2: social life	0.69 (0.64–0.74), 454
Item 3: family life/home responsibilities	0.69 (0.63–0.73), 443
Item 4: days lost	0.71 (0.65–0.75), 377
Item 5: days underproductive	0.67 (0.61–0.72), 402
Total SDS (sum of items 1–3)	0.72 (0.67–0.77), 403

Abbreviations: CI, confidence interval; ICC, intraclass correlation coefficient; SDS, Sheehan Disability Scale.

Table 4 SDS construct validity correlations at week 9

SDS item/subscale	DSM-IV ADHD RS inattention subscale	DSM-IV ADHD RS hyperactivity/impulsivity subscale	DSM-IV ADHD RS total score	CGI-I	CGI-S	ASRS hyperactivity/impulsivity subscale	ASRS inattention subscale	ASRS total score
Item 1: work/school	0.70*	0.58*	0.69*	0.66*	0.67*	0.61*	0.74*	0.73*
Item 2: social life	0.62*	0.58*	0.64*	0.58*	0.59*	0.63*	0.67*	0.70*
Item 3: family life/home responsibilities	0.62*	0.56*	0.63*	0.59*	0.60*	0.62*	0.68*	0.69*
SDS total score	0.70*	0.62*	0.71*	0.66*	0.67*	0.67*	0.76*	0.77*

Note:

* P<0.01.

Abbreviations: ASRS, Adult Self-Report Scale; CGI-I, Clinical Global Impressions Scale for Global Improvement; CGI-S, Clinical Global Impressions Scale for Severity of Illness; DSM-IV ADHD RS, Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) Attention-Deficit/Hyperactivity Disorder Rating Scale; SDS, Sheehan Disability Scale.

Table 5 Known-groups ANOVAs for the SDStotal score based on the DSM-IV ADHD RS

DSM-IV ADHD RS cut points	Average SDS at baseline			Average SDS at week 9
	n	Mean (SD)	F statistic	n	Mean (SD)	F statistic
DSM-IV ADHD RS mean +0.25 (SD)	151	21.9 (5.5)	16.60*	158	20.6 (5.6)	276.36*
DSM-IV ADHD RS mean −0.25 (SD)	181	19.4 (5.7)		169	9.8 (6.1)

Note:

* P<0.01.

Abbreviations: ANOVAs, analyses of variance; DSM-IV ADHD RS, Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) Attention-Deficit/Hyperactivity Disorder Rating Scale; SD, standard deviation; SDS, Sheehan Disability Scale.

Table 6 Known-groups item-level ANOVAs for the SDS total score based on the ASRS

ASRS cut points	Average SDS at baseline			Average SDS at week 9
	n	Mean (SD)	F statistic	n	Mean (SD)	F statistic
ASRS mean +0.25 (SD)	165	23.5 (4.2)	120.25*	169	20.5 (5.5)	366.06*
ASRS mean −0.25 (SD)	153	17.8 (5.2)		161	8.9 (5.5)

Note:

* P<0.01.

Abbreviations: ANOVAs, analyses of variance; ASRS, Adult Self-Report Scale; SD, standard deviation; SDS, Sheehan Disability Scale.

Table 7 Ability of SDS to detect change

SDS item/subscale	Week 9 CGI-I group	SDS mean (SD), n	Guyatt’s improved versus unchanged
Item 1: work/school	Improved	−2.8 (2.8), 297	−1.45
	Unchanged	0.2 (2.1), 93
	Worsened	1.0 (1.4), 10
Item 2: social life	Improved	−2.3 (2.9), 333	−1.35
	Unchanged	0.2 (1.9), 103
	Worsened	0.9 (1.8), 10
Item 3: family life/home responsibilities	Improved	−2.5 (2.8), 326	−1.41
	Unchanged	−0.1 (1.7), 98
	Worsened	0.9 (1.6), 10
Item 4: days lost	Improved	−0.7 (1.9), 267	−0.30
	Unchanged	−0.1 (2.1), 81
	Worsened	0.4 (1.8), 10
Item 5: days underproductive	Improved	−1.8 (2.3), 284	−0.69
	Unchanged	−0.1 (2.5), 85
	Worsened	0.7 (1.9), 10
SDS total score	Improved	−7.5 (7.5), 290	−1.84
	Unchanged	0.7 (4.5), 88
	Worsened	2.8 (3.9), 10

Notes: Improved defined as CGI-I levels 1, 2, and 3; unchanged defined as CGI-I level 4; worsened defined as CGI-I levels 5, 6, and 7.

Abbreviations: CGI-I, Clinical Global Impressions Scale for Global Improvement; SD, standard deviation; SDS, Sheehan Disability Scale.

Table 8 Responder threshold estimates

Definitions	Estimate
Anchor-based method
Week 9 CGI-I: Response option 3= minimally improved [mean (SD), n]	−2.53 (4.6), 76
Distribution-based methods
SEM (screening-to-baseline reliability)	2.89
SEM (baseline-to-week 9 reliability)	3.23
0.5 SD	2.75

Abbreviations: CGI-I, Clinical Global Impressions Scale for Global Improvement; SD, standard deviation; SEM, standard error of measurement.

Figure 1 Cumulative distribution function.

Note: Negative change scores are indicative of improvement.
Abbreviation: MPH-LA, modified-release methylphenidate.