Table 4.

Standardized item loadings for the 8 selected items in a single factor model in exploratory and confirmatory subgroups

Item	Domain	Exploratory sample (n=166)	Confirmatory sample (n=154)
"I get sudden feelings of panic"	Anxiety	0.53*	0.49*
"I still enjoy the things I used to enjoy"	Depression	0.57*	0.52*
“Over the past month, in your most painful knee, is cold or heat (bath water) in this area occasionally painful?”	Neuropathic symptoms	0.52*	0.57*
“In the past month, did you feel tired on most days?”	Fatigue	0.62*	0.61*
“Does your pain or other bodily symptoms stop you from concentrating on what you are doing?”	Attention to pain	0.79*	0.81*
“Knee pain plus other pain below waist”	Pain distribution	0.44*	0.40*
"I keep thinking about how much it hurts"	Catastrophising	0.57*	0.58*
“In the past week, how much has your constant knee pain affected your sleep?”	Sleep	0.66*	0.69*

^*p<0.05