Factor structure and validity of the shoulder pain and disability index in a population-based study of people with shoulder symptoms

Table 3 Varimax rotated, normalised two-factor loadings for the thirteen SPADI items obtained by principal components factor analysis (N = 588)

	Factor 1	Factor 2
Pain section
PS.1 At its worst?	0.18	0.80
PS.2 When lying on the involved side?	0.20	0.78
PS.3 Reaching for something on a high shelf?	0.38	0.73
PS.4 Touching the back of your neck?	0.39	0.64
PS.5 Pushing with the involved arm?	0.39	0.69
Disability section:
DS.1 Washing your hair?	0.73	0.27
DS.2 Washing your back?	0.66	0.36
DS.3 Putting on an undershirt or pullover sweater?	0.80	0.32
DS.4 Putting on a shirt that buttons down the front?	0.80	0.17
DS.5 Putting on your pants?	0.73	0.22
DS.6 Placing an object on a high shelf?	0.63	0.44
DS.7 Carrying a heavy object of 10 pounds?	0.58	0.40
DS.8 Removing something from your back pocket?	0.69	0.30
Proportion of total variance explained	34.6%	26.8%

ISSN: 1471-2474