Table 3.

Results of exploratory factor analysis (EFA) of the 19 items of the FKSI-19 instrument, giving a 14-item two-factor solution (FKSI-14). The largest factor loading for each item is given in bold

Item	FKSI-19 domain	Question	FKSI-14 domain	F1	F2
GP1a	DRS-P	I have a lack of energy	PMS	0.716	0.370
GP4a	DRS-P	I have pain	PMS	0.565	0.175
HI7a	DRS-P	I feel fatigued	PMS	0.784	0.328
B1a	DRS-P	I have been short of breath	PMS	0.555	0.226
BP1a	DRS-P	I have bone pain	PMS	0.485	0.132
HI12a	DRS-P	I feel weak all over	PMS	0.812	0.304
C6	DRS-P	I have a good appetite	DLFWB	0.139	0.514
GF5	DRS-P	I am sleeping well	DLFWB	0.147	0.459
GE6a	DRS-E	I worry that my condition will get worse	PMS	0.469	0.183
GP2a	TSE	I have nausea	PMS	0.428	0.231
GP5a	TSE	I am bothered by side effects of treatment	PMS	0.436	0.139
GF1	FWB	I am able to work (include work at home)	DLFWB	0.264	0.641
GF3	FWB	I am able to enjoy life	DLFWB	0.300	0.836
GF7	FWB	I am content with the quality of my life right now	DLFWB	0.360	0.773

DLFWB daily life function and well-being, DRS-E disease-related symptoms-emotional, DRS-P disease-related symptoms-physical, FWB function/well-being, PMS physical and mental symptoms, TSE treatment side effects. The following FKSI-19 items were excluded: C2, “I am losing weight”; BRM3, “I am bothered by fevers”; L2, “I have been coughing”; RCC2, “I have had blood in my urine”; C5, “I have diarrhea”

^aReverse-scored