Table 4.

Univariate Cox regression analysis.

Variable			EQ-VASa				EQ-5D-5Lb					EORTC QLQ-C30c
			Hazard ratio (95% CI)		P value		Hazard ratio (95% CI)		P value		Hazard ratio (95% CI)			P value
Age			0.99 (0.97-1.02)		.583		0.98 (0.95-1.01)		.20		1.00 (0.98-1.03)			.83
Metastasis
	Brain	1.71 (0.74-3.94)		.21		0.32 (0.04-2.31)		.26		1.16 (0.42-3.2)			.78
	Lymph nodes	1.20 (0.77-1.87)		.42		1.42 (0.79-2.54)		.23		0.95 (0.56-1.63)			.86
	Bone	0.83 (0.54-1.29)		.41		0.85 (0.47-1.53)		.59		1.4 (0.81-2.43)			.22
	Lung	1.09 (0.69-1.69)		.71		0.73 (0.39-1.37)		.33		0.97 (0.57-1.65)			.91
	Pleura	0.42 (0.18-0.96)		.04		0.43 (0.13-1.39)		.16		0.90 (0.41-1.98)			.79
	Liver	1.64 (1.06-2.52)		.03		1.67 (0.94-2.99)		.08		0.87 (0.51-1.47)			.61
	Peritoneum	0.96 (0.35-2.63)		.94		0.78 (0.19-3.2)		.73		1.39 (0.5-3.84)			.52
	Skin	0.55 (0.2-1.52)		.25		0.82 (0.25-2.65)		.74		0.41 (0.1-1.7)			.22
	Other	0.67 (0.32-1.39)		.28		0.73 (0.26-2.04)		.55		1.79 (0.93-3.46)			.08
Progression			1.48 (0.91-2.37)		.11		1.15 (0.60-2.23)		.34		1.05 (0.58-1.88)			.88
Systemic group
	CDKd 4/6 inhibitors +/– endocrine therapy	Reference		Ref		Ref		Ref		Ref			Ref
	Chemotherapy	1.72 (0.77-3.85)		.19		1.48 (0.41-5.32)		.55		0.43 (0.2-0.94)			.03
	Endocrine therapy	2.29 (0.93-5.65)		.07		0.69 (0.11-4.21)		.69		0.60 (0.25-1.5)			.29
	HER2e-targeted therapy	1.7 (0.76-3.83)		.20		1.42 (0.38-5.4)		.60		0.54 (0.25-1.15)			.11

^aEQ-VAS: EuroQol Visual Analog Scale.

^bEQ-5D-5L: EuroQol 5 Dimension 5 Level.

^cEORTC QLQ-C30: European Organization for Research and Treatment of Cancer Quality of Life Questionnaire–Core 30 item.

^dCDK: cyclin-dependent kinase.

^eHER2: human epidermal growth factor receptor 2.