Cross-cultural validity of four quality of life scales in persons with spinal cord injury

Geyh, Szilvia; Fellinghauer, Bernd AG; Kirchberger, Inge; Post, Marcel WM

doi:10.1186/1477-7525-8-94

Health and Quality of Life Outcomes

Table 5 Rasch-based statistics for the different strategies applied to enhance the metric properties of the instruments (n = 243)

From: Cross-cultural validity of four quality of life scales in persons with spinal cord injury

Items	Strategy 1: Collapsing response scale						Strategy 2: Deleting misfitting items						Strategy 3: Merging DIF items						Strategy 4: Merging DIF items (Option 1 or 2)
	δ	SE	τ	z	p	r	δ	SE	τ	z	p	r	δ	SE	τ	z	p	r	δ	SE	τ	z	p	r
SWLS	recoding: 0 1 1 2 2 3 4																		no DIF in selected option
Overall					0.990	0.87					0.250	0.90					0.000^b	0.89
Ideal life	0.48	0.11	ord	-0.83	0.811		0.39	0.07	disord	-0.88	0.119		0.32	0.06	ord	-1.11	0.014
Life conditions	0.077	0.11	ord	0.08	0.910		0.06	0.07	ord	-0.43	0.220		0.11	0.06	ord	-0.56	0.006^b
Life satisfaction	-0.56	0.11	ord	0.75	0.870		-0.45	0.07	ord	0.43	0.758		-0.24	0.06	ord	0.07	0.165
Got things I want	del						del						merg
Change nothing in life	del						del						merg
Merged item 4. and 5.													-0.19	0.04	ord	2.67^a	0.038
LiSAT	recoding: 0 1 1 1 2 3																		recoding: 0 1 1 1 2 3
Overall					0.074	0.81					0.106	0.80					0.000^b	0.86					0.125	0.81
Life as a whole	-0.44	0.12	ord	-1.72	0.022		del						-0.08	0.07	ord	-1.96	0.000^b		-0.35	0.122	ord	-1.38	0.037
Self care	-0.08	0.10	ord	0.32	0.739		-0.08	0.06	ord	1.69	0.558		0.12	0.05	ord	0.68	0.626		0.00	0.098	ord	0.65	0.671
Vocational situation	0.27	0.10	ord	-1.82	0.382		0.10	0.06	disord	0.25	0.125		0.30	0.06	disord	-0.55	0.321		0.34	0.105	ord	-1.35	0.454
Financial situation	0.12	0.11	ord	0.53	0.305		del						merg						merg
Leisure situation	0.41	0.11	ord	-1.55	0.279		0.18	0.06	ord	-1.22	0.014		merg						merg
Sexual life	1.39	0.11	ord	1.93	0.055		0.86	0.06	disord	0.50	0.777		0.995	0.06	disord	-0.11	0.476		1.45	0.112	ord	2.23	0.049
Partner relations	del						del						-0.27	0.07	disord	2.77^a	0.008		del
Family life	del						del						-0.53	0.06	disord	2.74^a	0.021		del
Contact with friends	-1.67	0.11	ord	1.97	0.517		-1.06	0.07	disord	0.58	0.481		-0.77	0.07	disord	0.15	0.562		-1.63	0.110	ord	2.37	0.427
Merged item 4. and 5.													0.24	0.04	ord	-1.66	0.279		0.18	0.078	disord	-2.25	0.616
PWI	no recoding (one item disordered)
Overall											0.346	0.92					0.710	0.92
Whole life							0.17	0.04	ord	0.26	0.250		0.11	0.04	ord	-0.70	0.121
Living standard							0.06	0.04	ord	0.97	0.050		0.00	0.04	ord	1.66	0.427
Health							del						merg
Life achievement							0.09	0.04	ord	1.28	0.857		0.03	0.04	ord	1.62	0.646
Relationships							-0.35	0.04	ord	1.68	0.207		merg
Feeling safe							-0.08	0.04	ord	-1.04	0.481		merg
Feel part of community							-0.06	0.04	disord	0.06	0.598		-0.09	0.041	disord	0.495	0.730
Future security							0.18	0.04	ord	-0.46	0.681		merg
Merged item 3. and 8.													0.19	0.03	ord	0.54	0.949
Merged item 5. and 6.													-0.23	0.03	ord	-1.00	0.501
WHOQOL	no recoding (no disorder)
Overall											0.340	0.81					0.567	0.76
Health							0.12	0.10	ord	0.15	0.371		merg
Activities of daily living							0.68	0.09	ord	-0.30	0.240		0.58	0.08	ord	-0.29	0.604
Relationships							del						-0.41	0.08	ord	1.59	0.582
Living place							del						-0.34	0.08	ord	1.92	0.475
Quality of life							-0.80	0.10	ord	0.07	0.376		merg
Merged item 1. and 5.													0.16	0.06	ord	-2.20	0.208

Index:
a: Exceeds the critical value of z > +/-2.5
b: Below the Bonferroni corrected probability level of p < 0.05/number of items (SWLS and PWI: p < 0.01; LISAT and PWI: p < 0.006)
Abbreviations:
SWLS: Satisfaction with life scale; LISAT: Life satisfaction questionnaire; PWI: Personal well-being index; WHOQoL: World Health Organization quality of life assessment; DIF: Differential item functioning; δ: Item location in logits (delta); SE: Standard error of item location; τ: Ordering of the response scale thresholds (tau); z: Standard normal distributed test value z; p: Probability of the Chi² test; r: Person reliability index; del: Item deleted due to misfit; merg: Item merged due to DIF; ord: Response scale thresholds ordered; disord: Response scale thresholds disordered

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ISSN: 1477-7525

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