Evaluation of the SCL-9S, a short version of the symptom checklist-90-R, on psychiatric patients in Sweden by using Rasch analysis

Figures & data

Table 1. Participant characteristics.

	Inpatients	Outpatients	p Value
n	167	668
Age, M (SD)	45.9 (19.6)	36.3 (13.5)	<0.001
Age range	18–91	18–87
Gender
Man	63 (39%)	191 (29%)	0.047
Woman	98 (60%)	455 (68%)
Missing data	4 (1%)	22 (3%)
Living
Single	106 (64%)	335 (50%)	0.002
Cohabitation	56 (32%)	311 (47%)
Missing data	5 (0%)	22 (3%)
Education
Not competed	6 (4%)	15 (2%)	0.404
Primary school	40 (24%)	100 (15%)	0.008
Upper secondary school	72 (43%)	382 (57%)	<0.001
College/University	45 (27%)	154 (23%)	0.310
Missing data	4 (2%)	17 (3%)
Occupation
Gainfully employed	38 (23%)	182 (27%)	0.253
Unemployed	9 (5%)	46 (7%)	0.602
Student	13 (8%)	66 (10%)	0.462
Sick leave	64 (38%)	297 (44%)	0.163
Retirement pension	35 (21%)	25 (4%)	<0.001
Missing data	8 (5%)	52 (8%)
Diagnosis^a
ADHD	8 (5%)	141 (21%)	<0.001
ASD	9 (5%)	51 (8%)	0.402
Anxiety disorder	23 (14%)	191 (29%)	<0.001
Bipolar disorder	22 (13%)	69 (10%)	0.330
Major Depressive disorder	46 (28%)	139 (21%)	0.076
Personality disorder	2 (1%)	57 (9%)	<0.001
Psychosis	3 (2%)	11 (2%)	1.000
Schizophrenia	6 (4%)	29 (4%)	0.830
Eating disorders	2 (1%)	28 (4%)	0.065
Abuse	0 (0%)	5 (1%)	0.589
Treatment^a
Medication	152 (91%)	498 (75%)	<0.001
Electroconvulsive therapy	31 (19%)	33 (5%)	<0.001
Counselling	70 (42%)	390 (60%)	<0.001
Psychotherapy	23 (14%)	265 (40%)	<0.001
Mental health (1–5), M (SD)	3.12 (1.12)	2.91 (1.07)	0.027

SD: standard deviation; ADHD: attention deficit hyperactivity disorder; ASD: autism spectrum disorder.

^aA patient may have more than one diagnosis or treatment, thus, percentages may not add up to 100%. Fischer’s exact test analyzed all variables except age and mental health (t-test).

Table 2. Items and dimensions of the SCL-90-R and SCL-9S.

SCL-90-R dimension	Item position on the SCL-90-R	Item position on the SCL-9S^a
1. Somatization	42. Soreness of your muscles	1. Värk eller ömhet i musklerna
2. Obsessive-compulsive	28. Feeling blocked in getting things done	2. Att inte få saker och ting gjorda
3. Social insecurity	6. Feeling critical of others	3. Att känna dig kritisk mot andra
4. Depression	15. Thoughts of ending your life	4. Tankar på att ta ditt liv
5. Anxiety	72. Spells of terror or panic	5. Ångest eller panikattacker
6. Hostility	81. Shouting or throwing things	6. Att du skriker eller kastar saker
7. Phobic fear	47. Feeling afraid to travel on buses, subways, or trains	7. Rädsla för att åka med tåg, buss, spårvagn eller tunnelbana
8. Paranoid thinking	18. Feeling that most people cannot be trusted	8. En känsla av att andra människor inte går att lita på
9. Psychoticism	7. The idea that someone else can control your thoughts	9. Känslan av att någon annan kan kontrollera dina tankar

^aFrom the Swedish validation of the SCL-90-R by Fridell et al. [24].

Table 3. Summary statistics for the five SCL-9S rating scale categories for inpatients (IP) and outpatients (OP).

	Category	Frequency of use (%)		Average SCL-9S person measure (logits)		Threshold measure		Category infit mean square		Category outfit mean square
		IP	OP	IP	OP	IP	OP	IP	OP	IP	OP
0	Not at all	665 (44)	2306 (38)	−1.36	−1.38	None	None	0.97	0.90	1.00	1.03
1	A little bit	277 (18)	1141 (19)	−0.64	−0.61	−0.39	−0.35	1.08	1.08	0.87	0.94
2	Moderately	225 (15)	932 (16)	−0.32	−0.17	−0.19	−0.28	0.91	0.92	0.77	0.85
3	Quite a bit	192 (13)	927 (15)	0.00	0.15	0.03	−0.03	1.10	1.05	1.25	1.13
4	Extremely	144 (10)	706 (12)	0.43	0.59	0.55	0.65	1.14	1.17	1.14	1.19

Table 4. Fit statistics.

Symptom	Item (SCL-90-R #)	All			IP	OP
		Item logit measure	Infit MnSq	Outfit MnSq	Item logit measure	Item logit measure	DIF
1	Soreness of your muscles (42)	−0.51	1.36	1.58	−0.35	−0.55	0.20
2	Feeling blocked in getting things done (28)	−0.92	0.95	1.08	−0.88	−0.92	0.03
3	Feeling critical of others (6)	−0.31	0.81	0.86	−0.16	−0.35	0.18
4	Thoughts of ending your life (15)	0.46	1.16	1.13	−0.05	0.58	−0.63
5	Spells of terror or panic (72)	−0.53	0.73	0.72	−0.71	−0.48	−0.23
6	Shouting or throwing things (81)	0.91	1.18	1.05	1.39	0.83	0.56
7	Feeling afraid to travel on buses, subways, or trains (47)	0.35	1.29	1.09	0.45	0.33	0.12
8	Feeling that most people cannot be trusted (18)	−0.39	0.74	0.72	−0.24	−0.42	0.18
9	The idea that someone else can control your thoughts (7)	0.93	1.36	1.13	0.61	1.01	−0.39

DIF: differential item functioning.

Table 5. Item mean raw score (M) and standard deviations (SD) for men and women in the inpatient (IP) and outpatient (OP) groups.^a

Symptom	Item (SCL-90-R #)	IP						OP
		All IP		Women		Men		All OP		Women		Men
		(n = 167)		(n = 98)		(n = 63)		(n = 668)		(n = 455)		(n = 191)
		M	SD	M	SD	M	SD	M	SD	M	SD	M	SD
1	Soreness of your muscles (42)	1.53	1.34	1.59	1.42	1.48	1.19	2.01	1.43	2.25	1.40	1.42	1.34
2	Feeling blocked in getting things done (28)	2.13	1.27	2.07	1.27	2.30	1.27	2.45	1.25	2.46	1.26	2.43	1.25
3	Feeling critical of others (6)	1.32	1.15	1.18	1.09	1.51	1.21	1.75	1.21	1.77	1.21	1.74	1.21
4	Thoughts of ending your life (15)	1.22	1.43	1.30	1.47	1.08	1.42	0.79	1.20	0.75	1.16	0.85	1.27
5	Spells of terror or panic (72)	1.95	1.40	2.11	1.45	1.75	1.34	1.94	1.31	2.00	1.28	1.77	1.37
6	Shouting or throwing things (81)	0.27	0.74	0.34	0.84	0.19	0.59	0.60	1.02	0.62	1.06	0.54	0.94
7	Feeling afraid to travel on buses, subways, or trains (47)	0.79	1.31	0.87	1.34	0.70	1.30	1.00	1.40	0.99	1.37	1.04	1.47
8	Feeling that most people cannot be trusted (18)	1.40	1.36	1.40	1.33	1.44	1.41	1.85	1.38	1.87	1.38	1.80	1.41
9	The idea that someone else can control your thoughts (7)	0.64	1.19	0.79	1.33	0.46	0.98	0.49	1.01	0.50	1.02	0.50	1.00
Mean score		1.25	0.73	1.29	0.78	1.22	0.68	1.43	0.73	1.47	0.71	1.34	0.75

^aGender information was missing in six IP and 22 OP cases.

Figure 2. Person item maps for men and women. Note. M: mean of person or item distribution; S: one standard deviation from the person or item mean; T: two standard deviations from the person or item mean.

Figure 3. Cluster analysis of SCL-9S data of psychiatric in- and outpatients.

Table 6. Mean scores per item of the SCL9S across patient clusters.

Item	Cluster 1	Cluster 2	Cluster 3
	N = 359	N = 269	N = 207
1 Soreness of your muscles	0.92^a	2.99^c	2.23^b
2 Feeling blocked in getting things done	1.72^a	2.89^b	2.93^b
3 Feeling critical of others	0.99^a	2.09^b	2.30^c
4 Thoughts of ending your life	0.48^a	0.49^a	2.06^b
5 Spells of terror or panic	1.23^a	1.96^b	3.16^c
6 Shouting or throwing things	0.20^a	0.47^b	1.17^c
7 Feeling afraid to travel on buses, subways, or trains	0.28^a	0.60^b	2.60^c
8 Feeling that most people cannot be trusted	0.91^a	1.81^b	3.15^c
9 The idea that someone else can control your thoughts	0.23^a	0.35^a	1.26^c
Mean score	0.78^a	1.51^b	2.32^c
SD	0.37	0.35	0.48
Skewness (SE)	−0.11 (0.13)	0.40 (0.15)	0.49 (0.17)
Kurtosis (SE)	−0.59 (0.26)	−0.19 (0.30)	−0.14 (0.34)

^a,b,cMeans in a row with different superscript are significantly different (p < 0.05) according to Tukey's HSD test. Means in italic are typical for that cluster.

Figure 1. Person item maps for the psychiatric inpatient and outpatient groups. Note. M: mean of person or item distribution; S: one standard deviation from the person or item mean; T: two standard deviations from the person or item mean.

Fridell M, Cesarec Z, Johansson M, et al. SCL-90. Svensk Normering. Standardisering och Validering av Symtomskalan [SCL 90. Swedish Normalisation, Standardisation and Validation of the Symptom Scale.]. Stockholm: Statens Institutionsstyrelse SiS; 2002.

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