Table 1a.

Cox regression analyses for progression-free survival in the overall analysis group, showing hazard ratios for CDK4/6i + ET versus ET.

Setting	Unadjusted analysis		First adjusted analysis a		Second adjusted analysis b
	HR (95% CI)	P value	HR (95% CI)	P value	HR (95% CI)	P value
First line	0.81 (0.54, 1.22)	0.32	0.87 (0.56, 1.34)	0.52	0.87 (0.58, 1.32)	0.52
Second line	1.04 (0.72, 1.50)	0.84	0.90 (0.60, 1.35)	0.61	0.84 (0.57, 1.24)	0.39
Third line	0.96 (0.60, 1.54)	0.86	0.85 (0.50, 1.43)	0.53	0.83 (0.51, 1.35)	0.45

CDK4/6i, CDK4/6 inhibitor; CI, confidence interval; ET, endocrine therapy; HR, hazard ratio.

^aHRs were adjusted for age, time from primary diagnosis to metastasis, ECOG, grade, anti-endoctrine therapy, metastasis pattern, number of previous chemotherapies (at Setting 2 and 3), number of comorbidities.

^bHRs were obtained after variable selection process. At setting 1 the predictor anti-endocrine therapy were selected. At setting 2 age, metastasis pattern and number of previous chemotherapies were selected. At Setting 3, time from primary diagnosis to metastasis and number of comorbidities were selected.