Validation of the German version of the Neck Disability Index (NDI)

Table 2 Descriptive scale characteristics, factor structure, and reliability of the German version of the Neck Disability Index (NDI)

Item	Mean ± SD	Item difficulty	Factor loading	Corrected item-total correlation	Alpha if item deleted
Pain intensity	2.24 ± 0.77	0.45	0.57	0.44	0.80
Personal care	0.45 ± 0.63	0.09	0.67	0.54	0.80
Lifting	1.53 ± 1.12	0.31	0.56	0.42	0.80
Reading	2.07 ± 1.08	0.41	0.61	0.52	0.80
Headache	2.17 ± 1.38	0.43	0.48	0.38	0.81
Concentration	1.15 ± 1.04	0.23	0.71	0.59	0.78
Work	1.14 ± 1.00	0.23	0.76	0.63	0.78
Driving	2.05 ± 1.32	0.41	0.55	0.44	0.80
Sleeping	1.64 ± 1.26	0.33	0.59	0.47	0.79
Recreation	1.67 ± 0.86	0.33	0.75	0.64	0.78

ISSN: 1471-2474