Measuring depression after spinal cord injury: Development and psychometric characteristics of the SCI-QOL Depression item bank and linkage with PHQ-9

Figures & data

Table 1. Demographic and Injury Characteristics of Calibration Sample and PHQ Crosswalk Subsample

Variable	Calibration Sample (N = 716) Mean (SD), N (%)	PHQ Crosswalk Subsample (n = 465)
Age (years)	43.0 (15.3)	41.8 (15.6)
Sex
Male	558 (78%)	363 (78%)
Female	158 (22%)	102 (22%)
Ethnicity
Hispanic	81 (11%)	57 (12%)
Non-Hispanic	631 (88%)	405 (87%)
Not provided (refused)	4 (1%)	3 (1%)
Race
Caucasian	505 (70%)	319 (68.6%)
African-American	125 (17%)	90 (19.4%)
Asian	8 (1%)	5 (1.1%)
More than one race	9 (1%)	8 (1.7%)
Other	56 (8%)	39 (8.3%)
Not Provided (refused)	13 (2%)	4 (0.9%)
Time Since Injury	7.1 (10.0)	6.56 (9.5)
<1 year post injury	195 (27%)	161 (34.6%)
1–3 years post injury	186 (26%)	118 (25.4%)
>3 years post injury	335 (47%)	186 (40.0%)
Diagnosis
Paraplegia Complete	182 (25%)	128 (27%)
Paraplegia Incomplete	143 (20%)	90 (19%)
Tetraplegia Complete	157 (22%)	98 (22%)
Tetraplegia Incomplete	230 (32%)	147 (32%)
Unknown/Missing	2 (0%)	2 (0.4%)

Table 2. SCI-QOL Depression Descriptive Item Statistics (Calibration Sample, n = 716)

Item ID	Item Stem	Mean	SD	% at Min	% at Max
Dep_31	I had given up on my dreams.	1.76	1.098	59.9	2.7
EDDEP04^PN	I felt worthless.	1.66	1.025	63.6	2.5
EDDEP05^PN	I felt that I had nothing to look forward to.	1.66	1.017	63.1	2.2
EDDEP06^PN	I felt helpless.	1.99	1.155	48.0	4.5
EDDEP07^PN	I withdrew from other people.	1.72	0.973	56.6	1.1
EDDEP09^PN	I felt that nothing could cheer me up.	1.73	0.988	56.7	1.7
EDDEP17^PN	I felt sad.	2.38	1.122	27.0	4.7
EDDEP19^PN	I felt that I wanted to give up on everything.	1.42	0.853	75.8	1.3
EDDEP28^PN	I felt lonely.	2.24	1.184	37.2	4.1
EDDEP29^PN	I felt depressed.	2.04	1.112	43.3	3.4
EDDEP31^PN	I felt discouraged about the future.	2.16	1.139	39.1	3.4
EDDEP35^PN	I found that things in my life were overwhelming.	2.05	1.085	41.3	3.4
EDDEP36^PN	I felt unhappy.	2.22	1.117	33.8	3.8
EDDEP39^PN	I felt I had no reason for living.	1.35	0.805	79.3	1.4
EDDEP41^PN	I felt hopeless.	1.65	0.987	63.0	2.0
EDDEP45^PN	I felt that nothing was interesting.	1.78	1.022	54.6	2.1
EDDEP46^PN	I felt pessimistic.	2.01	1.073	43.4	2.2
EDDEP48^PN	I felt that my life was empty.	1.78	1.055	55.9	2.5
EDDEP54^PN	I felt emotionally exhausted.	2.09	1.127	42.0	3.6
NQDEP01	I felt lonely even when I was with other people.	1.74	1.000	57.4	1.8
NQDEP08^N	I was critical of myself for my mistakes.	2.47	1.242	30.3	7.0
NQDEP15	I wished I were dead and away from it all.	1.34	0.832	81.8	1.7
NQDEP16	I thought about suicide.	1.20	0.625	88.5	.8
NQDEP20^N	I felt unloved.	1.53	0.931	69.0	2.1
NQDEP22	I felt that others would be better off if I were dead.	1.40	0.890	78.4	2.4
NQDEP26^N	I had trouble keeping my mind on what I was doing.	2.09	1.058	38.4	2.0
NQDEP29^N	I felt like I needed help for my depression.	1.66	0.997	62.4	1.8
NQDEP30^N	I had trouble enjoying things that I used to enjoy.	2.40	1.255	34.0	7.1

^PPROMIS Item.

^NNeuro-QOL Item.

*Context for all items was: ‘In the past 7 days…’.

Response set was: 1 = Never/2 = Rarely/3 = Sometimes/4 = Often/5 = Always.

Bold text indicates items selected for the short form 10a. SCI-QOL Items and parameters copyright © 2015 David Tulsky and Kessler Foundation. All Rights Reserved. Neuro-QOL items © David Cella. PROMIS items © Promis Health Organization. All Rights reserved. Scales should be accessed and used through the corresponding author or http://www.assessmentcenter.net. Do not modify items without permission from the copyright holder.

Table 3. SCI-QOL Depression Items and IRT Parameters (Calibration Sample, N = 716)

Item ID	Item Response Theory Calibration Statistics
	Item Stem	Slope	Threshold 1	Threshold 2	Threshold 3	Threshold 4
Dep_31	I had given up on my dreams.	2.15998	0.41389	1.02506	1.69092	2.54440
EDDEP04^PN	I felt worthless.	3.55165	0.47556	0.93740	1.70107	2.18427
EDDEP05^PN	I felt that I had nothing to look forward to.	4.23071	0.44395	0.93198	1.65946	2.14865
EDDEP06^PN	I felt helpless.	2.32652	0.05125	0.66820	1.62690	2.18065
EDDEP07^PN	I withdrew from other people.	2.28323	0.30366	1.01594	1.97905	2.98945
EDDEP09^PN	I felt that nothing could cheer me up.	3.27472	0.28513	0.93234	1.79038	2.35423
EDDEP17^PN	I felt sad.	2.82139	−0.60395	0.22965	1.27734	1.98449
EDDEP19^PN	I felt that I wanted to give up on everything.	3.43829	0.83163	1.32431	1.98523	2.56590
EDDEP28^PN	I felt lonely.	1.77956	−0.33732	0.38464	1.45255	2.49997
EDDEP29^PN	I felt depressed.	3.40087	−0.07614	0.52751	1.47203	2.06163
EDDEP31^PN	I felt discouraged about the future.	2.77590	−0.19851	0.42318	1.39802	2.18645
EDDEP35^PN	I found that things in my life were overwhelming.	2.15291	−0.15561	0.62625	1.82065	2.40451
EDDEP36^PN	I felt unhappy.	3.28354	−0.35504	0.38967	1.34430	2.02462
EDDEP39^PN	I felt I had no reason for living.	3.39440	0.96514	1.48114	2.01474	2.49881
EDDEP41^PN	I felt hopeless.	4.22822	0.44127	0.96638	1.71221	2.21806
EDDEP45^PN	I felt that nothing was interesting.	2.52519	0.24102	0.89763	1.84310	2.48422
EDDEP46^PN	I felt pessimistic.	2.11924	−0.10251	0.64033	1.79079	2.67257
EDDEP48^PN	I felt that my life was empty.	3.02589	0.26893	0.91047	1.64966	2.28172
EDDEP54^PN	I felt emotionally exhausted.	2.09932	−0.14714	0.52312	1.68354	2.37133
NQDEP01	I felt lonely even when I was with other people.	2.64925	0.30872	0.89880	1.88422	2.55140
NQDEP08^N	I was critical of myself for my mistakes.	1.39097	−0.67682	0.14277	1.41130	2.44408
NQDEP15	I wished I were dead and away from it all.	3.13286	1.08723	1.48687	2.01529	2.45718
NQDEP16	I thought about suicide.	2.59718	1.46551	1.89301	2.56600	2.97717
NQDEP20^N	I felt unloved.	1.89448	0.72376	1.40645	2.34282	2.86678
NQDEP22	I felt that others would be better off if I were dead.	2.76672	0.96544	1.42641	2.00417	2.36611
NQDEP26^N	I had trouble keeping my mind on what I was doing.	1.59980	−0.28470	0.63940	1.96753	3.14329
NQDEP29^N	I felt like I needed help for my depression.	2.19849	0.48058	1.08175	1.96821	2.70108
NQDEP30^N	I had trouble enjoying things that I used to enjoy.	1.92691	−0.41660	0.20044	1.27276	2.02554

^PPROMIS Item.

^NNeuro-QOL Item.

*Context for all items was: ‘In the past 7 days…’.

Response set was: 1=Never/2=Rarely/3=Sometimes/4=Often/5=Always.

Bold text indicates items selected for the short form 10a. SCI-QOL Items and parameters copyright © 2015 David Tulsky and Kessler Foundation. All Rights Reserved. Neuro-QOL items © David Cella. PROMIS items © Promis Health Organization. All Rights reserved. Scales should be accessed and used through the corresponding author or http://www.assessmentcenter.net. Do not modify items without permission from the copyright holder.

Table 4. Linking Table: SCI-QOL Depression and PHQ-9

PHQ- 9	SCI-QOL	SE
Raw Score	T-Score
9*	22	9.85
10	46	3.50
11	48	2.50
12	49	2.00
13	50	1.70
14	51	1.48
15	52	1.32
16	53	1.19
17	53	1.09
18	54	1.00
19	55	0.92
20	55	0.86
21	56	0.80
22	56	0.75
23	57	0.71
24	58	0.67
25	58	0.63
26	59	0.59
27	60	0.56
28	60	0.54
29	61	0.51
30	62	0.49
31	63	0.47
32	63	0.45
33	64	0.43
34	65	0.41
35	66	0.40
36	67	0.38

*Note: PHQ items were scored 1–4.

Table 5. T-score lookup table for SCI-QOL Depression Short Form 10a

RAW SCORE	T-SCORE	STANDARD ERROR
10	38.3	5.8
11	44.6	3.5
12	47.1	3.1
13	48.9	2.7
14	50.4	2.4
15	51.6	2.2
16	52.7	2.1
17	53.7	2.0
18	54.6	2.0
19	55.4	1.9
20	56.3	1.9
21	57.0	1.9
22	57.8	1.9
23	58.6	1.9
24	59.3	1.9
25	60.1	1.9
26	60.8	1.9
27	61.5	1.9
28	62.2	1.9
29	62.9	1.9
30	63.6	1.9
31	64.3	1.9
32	65.0	1.9
33	65.7	1.8
34	66.3	1.8
35	67.0	1.8
36	67.6	1.8
37	68.3	1.8
38	68.9	1.8
39	69.6	1.8
40	70.3	1.8
41	71.0	1.9
42	71.7	1.9
43	72.5	2.0
44	73.3	2.0
45	74.2	2.1
46	75.2	2.3
47	76.2	2.4
48	77.6	2.7
49	79.0	2.9
50	81.9	3.7

Figure 1. SCI-QOL Depression Item Bank Information and Precision.

Figure 2. SCI-QOL Depression: Reliability by T-score and Assessment Method.

Table 6. Breadth of Coverage for SCI-QOL Depression, PHQ-9, and PHQ-2 (Calibration and PHQ Crosswalk Samples)

Measure/Mode		# Items Admin				Score
		Mean(SD)	Min	Max	Mean(SD)	Range	% Floor	% Ceiling	SE	Reliability
SCI-QOL Depression	Full Bank	28(0)	28	28	50.(9.6)	32.28–83.86	0.1%	3.1%	2.1	94.97%
	8-Item fixed length CAT	8(0)	8	8	50.7(9.4)	34.11–83.41	4.7%	0.1%	2.7	92.40%
	Variable-Length CAT (min 4/max 12)	6.41(3.3)	4	12	50.7(9.5)	32.84–82.56	3.5%	0.1%	3.0	91.45%
	Variable-Length CAT (min 4/max 8)	5.45(1.8)	4	8	50.7(9.4)	34.11–83.41	4.7%	0.1%	3.1	90.87%
	4-item Fixed-Length CAT	4(0)	4	4	50.7(9.1)	37.27–80.17	7.4%	0.1%	3.4	88.87%
PHQ-9		9(0)	9	9	48.7(8.7)	35.77–76.89	10.2%	0.2%	4.4	83.39%
PHQ-2		2(0)	2	2	49.0 (7.6)	42.08–69.84	46.0%	3.2%	5.8	74.54%

*Note: Sample mean values are reported for SE and Reliability, respectively.

Figure 3. Relationship Between SCI-QOL Depression T-scores and PHQ-9 Raw Scores.

Figure 4. Marginal Reliability of PHQ-2, PHQ-9, SCI-QOL Depression, and Combined (n = 465). Colors relate to the online version of the figure.

Figure 5. Scale information provided by the PHQ-2, PHQ-9, SCI-QOL Depression, and Combined. Note: Scale information is shown on the y-axis and T-scores are shown on the X-axis. The scale (or test) information curve (or function) indicates the level of information (i.e. reliability) provided by the scale over the range of the construct continuum. Colors relate to the online version of the figure.